Temperature microstructure in Howe Sound

Bilodeau, Laurent Ernest

doi:10.14288/1.0053180

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Temperature microstructure in Howe Sound Bilodeau, Laurent Ernest 1979

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Title	Temperature microstructure in Howe Sound
Creator	Bilodeau, Laurent Ernest
Date Issued	1979
Description	Temperature microstructure observations obtained in Howe Sound are presented and related to their oceanographic context, In some instances, two free-falling probes have been launched simultaneously with separations of 10 to 20 m at the surface in an attempt to look at the lateral extent of temperature microstructure features. Patches of temperature gradient variance were found where the gradient presented peak values of both signs at smaller scales. These patches were usually observed by one probe only and seem to extend laterally over less than 20 m. In other instances the peak gradient values took mostly the same sign within a given patch. Such patches were usually detected by both probes, indicating that their horizontal extent is significantly larger than 20 m. These types of temperature microstructure are also discussed in terms of mechanisms that could provide an explanation for their existence. In Howe Sound's Inner Basin, the Deep Water occasionally receives large influxes of water from the Strait of Georgia. Otherwise, it stays essentially trapped behind a 75 m deep sill and becomes more homogeneous with time. A model is presented which relates the rate at which temperature becomes homogeneous to temperature gradient variance and the molecular coefficient of heat diffusion. Other parts of the water column are discussed in terms of the Osborn-Cox (1972) model of vertical heat transport.
Subject	Oceanography --Research --British Columbia --Howe Sound Deep-sea temperature --British Columbia --Howe Sound
Genre	Thesis/Dissertation
Type	Text
Language	eng
Date Available	2010-03-05
Provider	Vancouver : University of British Columbia Library
Rights	For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
DOI	10.14288/1.0053180
URI	http://hdl.handle.net/2429/21542
Degree	Master of Science - MSc
Program	Oceanography
Affiliation	Science, Faculty of Earth, Ocean and Atmospheric Sciences, Department of
Degree Grantor	University of British Columbia
Campus	UBCV
Scholarly Level	Unknown
AggregatedSourceRepository	DSpace

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TEMPERATURE MICROSTRUCTURE IN HOWE SOUND by LAURENT ERNEST BILODEAU B. A. Sc. Laval University, 1972 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES i n the Department of Physics and the I n s t i t u t e of Oceanography We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA SEPTEMBER 1978 Laurent Ernest Bilodeau, 1978 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r a n a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l m a k e i t f r e e l y a v a i l a b l e f o r r e f e r e n c e a n d s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e H e a d o f my D e p a r t m e n t o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f The U n i v e r s i t y o f B r i t i s h C o l u m b i a 2075 W e s b r o o k P l a c e V a n c o u v e r , C a n a d a V6T 1WS D a t e 12 QMtA A b s t r a c t Temperature m i c r o s t r u c t u r e o b s e r v a t i o n s o b t a i n e d i n Howe Sound a r e p r e s e n t e d and r e l a t e d t o t h e i r o c e a n o g r a p h i c c o n t e x t , I n some i n s t a n c e s , two f r e e - f a l l i n g p r o b e s have been l a u n c h e d s i m u l -t a n e o u s l y w i t h s e p a r a t i o n s o f 10 t o 20 m a t t h e s u r f a c e i n an a t t e m p t to l o o k a t t h e l a t e r a l e x t e n t o f t e m p e r a t u r e m i c r o s t r u c t u r e f e a t u r e s . P a t c h e s o f t e m p e r a t u r e g r a d i e n t v a r i a n c e were found where t h e g r a d i e n t p r e s e n t e d peak v a l u e s o f b o t h s i g n s a t s m a l l e r s c a l e s . These p a t c h e s were u s u a l l y o b s e r v e d by one probe o n l y and seem t o e x t e n d l a t -e r a l l y o v e r l e s s t h a n 20 m. I n o t h e r i n s t a n c e s t h e peak g r a d i e n t v a l u e s t o o k m o s t l y t h e same s i g n w i t h i n a g i v e n p a t c h . Such p a t c h e s were u s u a l l y d e t e c t e d by b o t h p r o b e s , i n d i c a t i n g t h a t t h e i r h o r i z o n t a l e x t e n t i s s i g n i f -i c a n t l y l a r g e r t h a n 20 m. These t y p e s o f t e m p e r a t u r e m i c r o s t r u c t u r e a r e a l s o d i s c u s s e d i n terms o f mechanisms t h a t c o u l d p r o v i d e an e x p l a n a t i o n f o r t h e i r e x i s t e n c e . I n Howe Sound's I n n e r B a s i n , t h e Deep Water o c c a s i o n a l l y r e c e i v e s l a r g e i n f l u x e s o f w a t e r from t h e S t r a i t o f G e o r g i a . O t h e r w i s e , i t s t a y s e s s e n t i a l l y t r a p p e d b e h i n d a 75 m deep s i l l and becomes more homogeneous w i t h t i m e . A model i s p r e s e n t e d w h i c h r e l a t e s t h e r a t e a t w h i c h t e m p e r a t u r e becomes homogeneous t o t e m p e r a t u r e g r a d i e n t v a r i a n c e and t he m o l e c u l a r c o e f f i c i e n t o f h e a t d i f f u s i o n . O t h e r p a r t s o f t h e wa t e r column a r e d i s c u s s e d i n terms o f t h e Osborn-Cox (1972) model o f v e r t i c a l h e a t t r a n s p o r t . i i i T a b l e o f c o n t e n t s Page A b s t r a c t i i T a b l e o f c o n t e n t s i i i L i s t o f t a b l e s v i L i s t o f f i g u r e s v i i Acknowledgments x i C h a p t e r I : I n t r o d u c t i o n 1 1.1 G e n e r a l i n t r o d u c t i o n 1 1.2 Howe Sound: geography, t i d e s , w i nds and r i v e r d i s c h a r g e 2 1.3 E a r l i e r i n v e s t i g a t i o n o f t h e p h y s i c a l oceanography o f Howe Sound 4 Ch a p t e r I I : New a s p e c t s o f t h e o c e a n o g r a p h i c and c u r r e n t meter d a t a 10 I I . 1 The I n t e r m e d i a t e Water . 10 I I . 2 The Deep Water r e n e w a l i n t h e F a l l o f 1973 . . 13 Ch a p t e r I I I : M i c r o s t r u c t u r e methods and d a t a p r o c e s s i n g . . 17 I I I . l P r o b e s and r e s o l u t i o n 17 I I I . 2 Method o f d a t a p r o c e s s i n g 19 I I I . 3 Summary of the d a t a 21 i v Page Chapter IV: Temperature structure of Howe Sound i n November 1973 and February 1974 . . . . 24 IV.1 Temperature structure i n November 1973 . . . 24 IV.2 Temperature structure i n February 1974 . . . 27 a) Recent evolution of water properties i n Howe Sound 27 b) Temperature structure i n the Outer Basin . . 28 c) Temperature structure i n the Inner Basin's Intermediate Water 30 d) Temperature structure i n the Inner Basin's Deep Water 32 IV. 3 Discussion a) An Intermediate Water c i r c u l a t i o n pattern? . . 34 b) The Osborn-Cox model 35 c) A model for an i s o l a t e d and inhomogeneous volume of f l u i d 41 Chapter V: Detailed aspect of temperature microstructure . 44 V. l Introduction 44 V.2 Detailed p r o f i l e s 45 a) November 1973 p r o f i l e s 45 b) Outer Basin, February 1974 . 47 c) Inner Basin Intermediate Water (February 1974) 50 d) Inner Basin Deep Water (February 1974) . . . 57 Page V.3 D i s c u s s i o n a) Summary of m i c r o s t r u c t u r e d e s c r i p t i o n . . . 59 b) R e l a t i o n s h i p between t e m p e r a t u r e and t e m p e r a t u r e g r a d i e n t m i c r o s t r u c t u r e . . . . 60 c) L a t e r a l e x t e n t o f m i c r o s t r u c t u r e 62 d) T u r b u l e n t o r n o t ? 64 e) D o u b l y - d i f f u s i v e o r n o t ? 67 C h a p t e r V I : C o n c l u s i o n 70 R e f e r e n c e s 72 T a b l e s 75 F i g u r e s 78 L i s t o f T a b l e s L i s t o f t h e l o c a t i o n s and t i m e s a t w h i c h d o u b l e drops were made d u r i n g the F e b r u a r y 1974 m i c r o -s t r u c t u r e c r u i s e , t o g e t h e r w i t h t h e s e p a r a t i o n of t h e p r o b e s a t l a u n c h and r e c o v e r y . L i s t o f t h e l o c a t i o n s and t i m e s a t w h i c h s i n g l e d rops were made d u r i n g t h e November 1973 m i c r o -s t r u c t u r e c r u i s e , t o g e t h e r w i t h t h e v a l u e s o b s e r v e d f o r t h e mean sq u a r e v e r t i c a l t e m p e r a t u r e g r a d i e n t . Mean square v a l u e s o f t h e v e r t i c a l t e m p e r a t u r e g r a d i e n t and n e t t e m p e r a t u r e change o b s e r v e d a c r o s s t h e I n t e r m e d i a t e Water d u r i n g t h e F e b r u a r y 1974 m i c r o s t r u c t u r e c r u i s e . v i i L i s t o f F i g u r e s F i g . 1 C h a r t o f Howe Sound. F i g . 2 L o n g i t u d i n a l s e c t i o n o f Howe Sound and c r o s s c h a n n e l s e c t i o n s made a t the s i l l and a t s t a t i o n Howe 4. F i g . 3 T y p i c a l w i n t e r p r o f i l e s o f t e m p e r a t u r e and s a l i n i t y i n t h e Out e r B a s i n and i n t h e I n n e r B a s i n o f Howe Sound. F i g . 4 Time s e r i e s o f t e m p e r a t u r e o b s e r v a t i o n s o b t a i n e d i n t h e Outer B a s i n a t dept h s o f 100 m and more. F i g . 5 Time s e r i e s o f t e m p e r a t u r e and s a l i n i t y o b s e r v a t i o n s o b t a i n e d between 20 and 75 m i n b o t h b a s i n s o f Howe Sound. F i g . 6 Time s e r i e s o f o b s e r v a t i o n s o f (a) t e m p e r a t u r e , (b) s a l i n i t y , (c) s i g m a - t and (d) d i s s o l v e d oxygen a t dept h s o f 100 m and more a t s t a t i o n Howe 4 ( I n n e r B a s i n ) . F i g . 7 L o n g i t u d i n a l s e c t i o n o f Howe Sound showing t h e l o c a t i o n o f the I n t e r m e d i a t e Water and of t h e Deep Water. F i g . 8 D i s t r i b u t i o n o f t e m p e r a t u r e , s a l i n i t y and d i s s o l v e d oxygen a l o n g t h e c e n t e r o f t h e I n n e r B a s i n on September 20, 1973. F i g . 9 D i s t r i b u t i o n o f T, S and D.0. a l o n g t h e c e n t e r o f t h e I n n e r B a s i n on November 13, 1973. F i g . 10 D i s t r i b u t i o n o f T, S and D.0. a l o n g the c e n t e r o f t h e I n n e r B a s i n on J a n u a r y 22, 1974. F i g . 11 Time s e r i e s o f t e m p e r a t u r e and N-S c u r r e n t v e l o c i t y o b t a i n e d a t s t a t i o n Howe 4 a t a de p t h o f 150 m by an Aanderaa c u r r e n t meter between O c t o b e r 3 and November 15, 1973. v i i i F i g . 12 D e s c r i p t i o n o f a "Pumpkin" m i c r o s t r u c t u r e p r o f i l e r and of i t s t e m p e r a t u r e s e n s i n g element. F i g . 13 L o c a t i o n o f t h e m i c r o s t r u c t u r e p r o f i l e s o b t a i n e d i n Howe Sound i n November 1973. F i g . 14 O v e r a l l p r o f i l e o f Drop P-10. F i g . 15 O v e r a l l p r o f i l e o f Drop P - l l . F i g . 16 O v e r a l l p r o f i l e o f Drop P-12. F i g . 17 O v e r a l l p r o f i l e o f Drop P-13. F i g . 18 O v e r a l l p r o f i l e o f Drop P-14. F i g . 19 O v e r a l l p r o f i l e o f Drop P-15. F i g . 20 O v e r a l l p r o f i l e o f Drop P-16. F i g . 21 D e t a i l e d segment from Drop P-12. F i g . 22 D e t a i l e d segment from Drop P-12. F i g . 23 D e t a i l e d segment f r o m Drop P-13. F i g . 24 D e t a i l e d segment from Drop P-13. F i g . 25 STD l o n g c h a n n e l s e c t i o n made on November 22, 1974 i n t h e I n n e r B a s i n o f Howe Sound. F i g . 26 STD c r o s s c h a n n e l s e c t i o n made on November 22, 1974 a t s t a t i o n Howe 4. F i g . 27 STD c r o s s c h a n n e l s e c t i o n made on November 22, 1974 a t s t a t i o n Howe 4.7. F i g . 28 L o c a t i o n o f t h e m i c r o s t r u c t u r e p r o f i l e s o b t a i n e d i n Howe Sound i n F e b r u a r y 1974. F i g . 29 O v e r a l l p r o f i l e o f Drop 6. F i g . 30 O v e r a l l p r o f i l e o f Drop 7. F i g . 31 O v e r a l l p r o f i l e o f Drop 8. i x F i g . 32 O v e r a l l p r o f i l e of Drop 9. F i g . 33 O v e r a l l p r o f i l e of Drop 10. F i g . 34 Deep part of Drop 7 with an expanded temperature scale. F i g . 35 Deep part of Drop 8 with an expanded temperature scale. F i g . 36 Deep part of Drop 9 with an expanded temperature scale. F i g . 37 Deep part of Drop 10 with an expanded temperature scale. F i g . 38 Comparison between STD p r o f i l e s made on January 22 and February 4, 1974, i n both Howe Sound's basins. Fi g . 39 STD long channel section made on February 6, 1974 i n Howe Sound's Inner Basin. F i g . 40 STD cross channel section made at s t a t i o n Howe 4 on February 6, 1974. F i g . 41 Detailed p r o f i l e from Drop 6. F i g . 42 Detailed p r o f i l e from Drop 6. F i g . 43 Detailed p r o f i l e from Drop 6. F i g . 44 Detailed p r o f i l e from Drop 7. F i g . 45 Detailed p r o f i l e from Drop 7. F i g . 46 Detailed p r o f i l e from Drop 7. F i g . 47 Detailed p r o f i l e from Drop 8. F i g . 48 Detailed p r o f i l e from Drop 8. F i g . 49 Detailed p r o f i l e from Drop 9. F i g . 50 Detailed p r o f i l e from Drop 9. F i g . 51 Detailed p r o f i l e from Drop 9. F i g . 52 Detailed p r o f i l e from Drop 10. F i g . 53 Detailed p r o f i l e from Drop 10. X F i g . 54 D e t a i l e d p r o f i l e F i g . 55 D e t a i l e d p r o f i l e F i g . 56 D e t a i l e d p r o f i l e F i g . 57 D e t a i l e d p r o f i l e f r o m Drop 1 0 . from t h e Deep Water of Drop 7. from t h e Deep Water of Drop 7. f r o m t h e Deep Water of Drop 8. Acknowledgments I am g r e a t l y i n d e b t e d t o Dr Thomas Osborn f o r h i s s u p p o r t and a d v i c e t h r o u g h a l l phases o f t h e work w h i c h l e a d t o t h e c o m p l e t i o n o f t h i s t h e s i s . H i s e x p e r i e n c e , f i n a n c i a l h e l p , p a t i e n c e and o c c a s i o n a l l a c k o f i t were a l l i n v a l u a b l e . I would a l s o l i k e t o t h a n k Dr P a u l L e b l o n d f o r h i s d e t a i l e d and p o s i t i v e c r i t i c i s m o f t h e e a r l y and f i n a l d r a f t s o f t h i s t h e s i s , and Dr G. L. P i c k a r d and Dr R. W. B u r l i n g f o r v e r y a p p r o p r i a t e comments about t h e e a r l y d r a f t . 1 C h a p t e r I I n t r o d u c t i o n 1.1 G e n e r a l I n t r o d u c t i o n . The purpose o f t h i s t h e s i s i s t o p r e s e n t t e m p e r a t u r e m i c r o -s t r u c t u r e and f i n e s t r u c t u r e o b s e r v a t i o n s w h i c h were o b t a i n e d i n Howe Sound i n November 1973 and F e b r u a r y 1974, and t o i n v e s t i g a t e some o f t h e i r s i g n i f i c a n c e . The term " m i c r o s t r u c t u r e " a p p l i e s t o t h e d i s t r i b u t i o n o f o c e a n o g r a p h i c p r o p e r t i e s a t s c a l e s s m a l l e r t h a n one me t r e . O b s e r v a -t i o n s r e p o r t e d by Gregg e t a l . (1973) i n an o c e a n i c environment show t h a t most o f t h e v a r i a n c e o f t h e t e m p e r a t u r e g r a d i e n t i s found a t s c a l e s s m a l l e r t h a n 0.1 m. I n t h e d i s t r i b u t i o n o f s p e c t r a l d e n s i t i e s o f t he t e m p e r a t u r e g r a d i e n t , Gregg e t a l . found a s p e c t r a l minimum n e a r s c a l e s o f i m. G a r g e t t (1976) used t h i s t o d e f i n e " f i n e s t r u c t u r e " as a p p l y i n g t o s c a l e s l a r g e r t h a n a m e t r e , up t o t e n s o f m e t r e s . G a r g e t t ' s d e f i n i t i o n i s r e t a i n e d f o r t h i s t h e s i s and, c o n s e q u e n t l y , " m i c r o s t r u c t u r e " w i l l a p p l y h e r e t o s c a l e s s m a l l e r t h a n one m e t r e . L i t t l e i s known about t h e o c c u r r e n c e and t h e r o l e o f temper-a t u r e m i c r o s t r u c t u r e i n f j o r d s and i n l e t s . D r i n k w a t e r (1973) used t e m p e r a t u r e m i c r o s t r u c t u r e o b s e r v a t i o n s i n a s t u d y o f t h e r o l e o f t i d a l m i x i n g i n R u p e r t and H o l b e r g I n l e t s t o d e t e c t t h e o c c u r r e n c e o f 2 t u r b u l e n t s t i r r i n g . He found t h a t t u r b u l e n t s t i r r i n g o c c u r r e d i n a s s o c i a t i o n w i t h t i d a l c u r r e n t s and, n e a r t h e s u r f a c e , w i t h s u r f a c e w i n d s . He t r a c e d a mid-depth i n t r u s i o n i n t o H o l b e r g I n l e t and o b s e r v e d l e s s t e m p e r a t u r e m i c r o s t r u c t u r e away from the mouth of t h e i n l e t . No o t h e r p u b l i s h e d s t u d y d e s c r i b e d o r used t e m p e r a t u r e m i c r o s t r u c t u r e o b s e r v a t i o n s o b t a i n e d i n i n l e t s . Howe Sound was chosen f o r t h i s s t u d y because i t i s easy o f a c c e s s and because i t has been the f o c u s o f s e v e r a l i n v e s t i g a t i o n s w h i c h have p r o v i d e d much back g r o u n d i n f o r m a t i o n about i t s oceanography f o r t h e p e r i o d o f 1971 t o 1974. 1.2 Howe Sound: geography, t i d e s , w i n d , r i v e r d i s c h a r g e . Howe Sound i s a f j o r d i n l e t l o c a t e d 30 km N o r t h West o f Vanc o u v e r , on t h e m a i n l a n d c o a s t o f the S t r a i t o f G e o r g i a (see f i g . 1 ) . I t c o n s i s t s o f two b a s i n s s e p a r a t e d by a s i l l w i t h a maximum d e p t h o f 70 m (see f i g . 1 ) . The Outer B a s i n ( a l s o c a l l e d S o u t h B a s i n ) f e a t u r e s a number of i s l a n d s and p a s s a g e s . The southernmost p a s s a g e , t h e Queen C h a r l o t t e C h a n n e l , i s about 250 m deep a l o n g i t s e n t i r e l e n g t h . The I n n e r B a s i n ( a l s o c a l l e d N o r t h B a s i n ) has a maximum d e p t h o f 290 m and a mean w i d t h o f about 3 km. The s i l l i s l o c a t e d 28 km from t h e mouth o f Howe Sound and 17 km from t h e head. A c r o s s c h a n n e l p r o f i l e of t h e s i l l i s p r e s e n t e d i n f i g . 2. 3 P o i n t A t k i n s o n i s the c l o s e s t t i d a l r e f e r e n c e p o i n t t o Howe Sound. A t P o i n t A t k i n s o n , the a m p l i t u d e r a t i o o f t h e f o u r main c o n s t i -t u e n t s i s : K.l + °1 _ 2.810 + 1.555 _ . M 2 + S 2 2.979 + 0.748 D e f a n t (1961, p.307) d e s c r i b e s such a v a l u e o f t h e r a t i o as a mixed, m a i n l y s e m i - d i u r n a l t y p e . The t i d a l range a t Squamish (head o f Howe Sound) i s s m a l l e r t h a n t h a t o f P o i n t A t k i n s o n (mouth o f Howe Sound) by a few c e n t i m e t r e s w h i l e t h e phases l a g b e h i n d t h o s e o f P o i n t A t k i n s o n by a few m i n u t e s ( C a n a d i a n H y d r o g r a p h i c S e r v i c e , 1977). Thus t h e P o i n t A t k i n s o n t i d a l p r e d i c t i o n s can be used a c c u r a t e l y i n Howe Sound. The mean t i d a l range a t Squamish i s 3.1 m ( C a n a d i a n Hydro-g r a p h i c S e r v i c e , 1977). F o r t h e purpose o f a s i m p l e t i d a l p r i s m model, th e mean de p t h o f t h e s i l l i s about 45 m. I f t h e f l o w were u n i f o r m o v e r t h e s i l l and i f t h e t i d e was p u r e l y s e m i - d i u r n a l , t h e mean t i d a l r ange would g i v e r i s e t o peak v e l o c i t i e s o f 8.5cm/sec. B u c k l e y (1977) r e p o r t s a c a l c u l a t i o n w h i c h s u g g e s t s t h a t b a r o c l i n i c t i d e s have a s m a l l e r b u t n o t n e g l i g i b l e e f f e c t . The A t m o s p h e r i c E n v i r o n m e n t S e r v i c e o p e r a t e s an anemometer w h i c h i s l o c a t e d i n t h e c e n t e r o f t h e v a l l e y , c l o s e t o t h e w a t e r , on the s i t e o f FMC o f Canada L t d . ( f i g . 1 ) , n e a r Squamish. The anemometer r e c o r d s the h o u r l y wind r u n and d i r e c t i o n i n o c t a n t s . Because o f t h e s t e e p mountains w h i c h l i n e t he v a l l e y , t h e w i n d blows o n l y seldom from t h e E a s t o f the West. D o w n - i n l e t w i n d s dominate d u r i n g w i n t e r ( O c t o b e r t o March) and u p - i n l e t w i nds dominate d u r i n g t h e summer ( A p r i l t o A u g u s t ) . A more d e t a i l e d s t u d y o f t h e h o u r l y w i n d r e c o r d s r e v e a l s t h a t t h e r e a r e p e r i o d s when the d i u r n a l w i n d c y c l e a c c o u n t s f o r most of t h e v a r i a n c e i n t h e wi n d p a t t e r n s . A t o t h e r t i m e s , i t i s the e f f e c t o f l a r g e r weather systems w h i c h p r e d o m i n a t e s w i t h p e r i o d s o f l i g h t o r s t r o n g w inds l a s t i n g from one t o f o u r days. The Squamish R i v e r c o n s t i t u t e s t h e main f r e s h w a t e r t r i b u t a r y o f t h e i n l e t . H o u r l y d i s c h a r g e measurements a r e t a k e n a t the D a i s y Lake Dam a t B r a c k e n d a l e , 25 km n o r t h o f Squamish (Water Survey o f 3 Canada s t a t i o n 8GA22). The r i v e r d i s c h a r g e i s t y p i c a l l y 100 m / s e c 3 i n w i n t e r (November t o A p r i l ) and t y p i c a l l y .3.00 m / s e c i n summer (May t o September). The d a i l y d i s c h a r g e can be e x p e c t e d t o peak o c c a s i o n a l l y a t s e v e r a l t i m e s t h e s e v a l u e s . The h i g h e s t d a i l y d i s c h a r g 3 o f t h e y e a r 1973 o c c u r r e d on O c t o b e r 28 w i t h a mean r a t e o f 1170 m /sec I.3 E a r l i e r i n v e s t i g a t i o n s o f Howe Sound's P h y s i c a l Oceanography. Many i n v e s t i g a t o r s have v i s i t e d Howe Sound. B u c k l e y (1977) g i v e s a d e t a i l e d l i s t g o i n g back t o C a p t a i n Vancouver. I n t h i s s t u d y , r e f e r e n c e i s made o n l y t o r e c e n t i n v e s t i g a t i o n s w h i c h c o v e r e d b o t h b a s i n s and the e n t i r e w a t e r column, c o n t i n u o u s l y o r on a m o n t h l y b a s i s . I n 1968, t h e M a r i n e S c i e n c e s B r a n c h o f the Department o f t h e Environ m e n t o f Canada c a r r i e d a program o f o b s e r v a t i o n o f t h e S t r a i t o f G e o r g i a w h i c h r e s u l t e d i n mon t h l y c r u i s e s i n Howe Sound ( C r e a n and Ages, 1971). The I n s t i t u t e o f Oceanography has c a r r i e d o u t a program 5 of m o n t h l y c r u i s e s i n Howe Sound between September 1971 and March 1974 and t h e d a t a a r e a v a i l a b l e i n D a t a R e p o r t s ( I.O.U.B.C., 1972, e t c . ) The C o a s t a l Oceanography Group o f the I n s t i t u t e o f Ocean S c i e n c e a t P a t r i c i a Bay has o p e r a t e d c h a i n s o f c u r r e n t m e t e r s i n b o t h b a s i n s o f Howe Sound. A s t a t i o n c l o s e t o Howe 4 was o c c u p i e d between November 1972 and F e b r u a r y 1974. The de p t h s w h i c h were m o n i t o r e d were: 3 m (Geodyne A-850 v e c t o r a v e r a g i n g c u r r e n t m e t e r ) , 5, 10, 15, 20, 30 and 150 m (Aanderaa RCM-4 c u r r e n t m e t e r s ) . The r e s u l t i n g d a t a have been p u b l i s h e d by B e l l (1975) under t h e form o f h i s t o g r a m s and p r o g r e s -s i v e v e c t o r d i a g r a m s . These d a t a have been a n a l y z e d by B e l l (1973) and P i c k a r d (1975) f r o m t h e p o i n t o f v i e w o f t h e e v o l u t i o n o f t h e Deep Water p r o p -e r t i e s and by B u c k l e y (1977) f o r t h e c u r r e n t meter d a t a . B u c k l e y (1977) a l s o c a r r i e d o ut an e x p e r i m e n t w i t h r a d a r - t r a c k e d drogues t o s t u d y t h e dynamics o f t h e S u r f a c e L a y e r . T y p i c a l w i n t e r p r o f i l e s o f t e m p e r a t u r e and s a l i n i t y i n Howe Sound a r e p r e s e n t e d i n f i g u r e 3. They were o b t a i n e d a t s t a t i o n s Howe 3 (O u t e r B a s i n ) and Howe 4 ( I n n e r B a s i n ) on F e b r u a r y 5 and 6, 1974. The p r o f i l e s i l l u s t r a t e t h a t t h e d e n s i t y o f t h e Howe Sound wa t e r i s c o n t r o l l e d by s a l i n i t y w h i c h i n c r e a s e s w i t h d e p t h . I n f i g . 3, te m p e r a t u r e i n c r e a s e s w i t h depth so t h a t i t s e f f e c t p a r t l y c o u n t e r a c t s t h a t o f s a l i n i t y . A t o t h e r t i m e s o f t h e y e a r , t e m p e r a t u r e may d e c r e a s e w i t h d e p t h o v e r p a r t o f t h e w a t e r column b u t i t p l a y s a s e c o n d a r y r o l e i n d e t e r m i n i n g t h e d e n s i t y o f t h e Howe Sound w a t e r . 6 F i g u r e 3 a l s o shows t h a t t e m p e r a t u r e and s a l i n i t y a r e v e r y homogeneous b e l o w 100 m i n the I n n e r B a s i n compared t o what i s f o u n d a t s i m i l a r d e p t h i n t h e Ou t e r B a s i n and compared t o what i s fo u n d i n b o t h b a s i n s above 100 m. P i c k a r d (1975) has i n d i c a t e d t h a t a m a j o r i t y o f t h e i n l e t s o f the B r i t i s h C o l umbia m a i n l a n d c o a s t show y e a r l y v a r i a t i o n s i n t h e i r Deep Water p r o p e r t i e s . These changes appear t o o c c u r t h r o u g h a d v e c t i v e p r o c e s s e s i n v o l v i n g w a t e r from t h e S t r a i t o f G e o r g i a . I n t h e Deep Water o f a few i n l e t s , s u c h y e a r l y v a r i a t i o n s a r e n o t a p p a r e n t ; the Deep Water t h e r e may r e m a i n t r a p p e d f o r more t h a n a y e a r a t a t i m e . Howe Sound appears t o c o n s t i t u t e a b o r d e r l i n e c a s e , presumably because o f i t s s h a l l o w s i l l . P i c k a r d (1975) d e s c r i b e s the e v o l u t i o n o f the Deep Water a t 200 m, a t s t a t i o n Howe 4, as p r e s e n t i n g a saw t o o t h p a t t e r n . Q u i c k changes o c c u r i n t h e s a l i n i t y , t e m p e r a t u r e and d i s s o l v e d oxygen. They a r e f o l l o w e d by s l o w changes w h i c h a r e a t t r i b u t e d t o non-a d v e c t i v e p r o c e s s e s such as t u r b u l e n t t r a n s f e r and b i o c h e m i c a l p r o c e s s e s ( f o r d i s s o l v e d o x y g e n ) . P i c k a r d (1975) i n d i c a t e d t h a t i t was n o t c l e a r w hether t h e Deep Water i n Howe Sound underwent a n n u a l changes o r more i n t e r m i t t e n t ones. B e l l (1973) s t u d i e d Deep Water r e p l a c e m e n t s i n t h e I n n e r B a s i n . He examined p r i n c i p a l l y t he e v o l u t i o n o f t h e d i s s o l v e d oxygen concen-t r a t i o n (D.O.) and s a l i n i t y a t d e p t h s o f 100, 150 and 200 m. I n a wa t e r volume such as t h e Deep Water o f t h e I n n e r B a s i n w h i c h i s i s o l a t e d f rom s u r f a c e exchanges and s u n l i g h t , D.O. v a l u e s a r e e x p e c t e d t o d e c r e a s e w i t h t i m e under t h e i n f l u e n c e of l o c a l b i o c h e m i c a l p r o c e s s e s . 7 S i m i l a r l y , s a l i n i t y i s e x p e c t e d t o d e c r e a s e w i t h t i m e because some f r e s h e r w a t e r from above g e t s t u r b u l e n t l y mixed i n t o t h e Deep Water. B e l l argued t h a t whenever D.0. and s a l i n i t y i n t h e I n n e r B a s i n ' s Deep Water showed s i g n i f i c a n t d e p a r t u r e s from t h e i r downward t r e n d s , some w a t e r from t h e O u t e r B a s i n had found i t s way i n t o t h e I n n e r B a s i n ' s Deep Water. He f o u n d a t the 100 m l e v e l , i n f l o w s appeared t o o c c u r f r e q u e n t l y , a l l y e a r round. A t t h e 150 and 200 m l e v e l s , m ajor i n -f l o w s appeared t o o c c u r a t l e a s t e v e r y few y e a r s . The volume and the d e p t h o f p e n e t r a t i o n o f the i n f l o w s appear v a r i a b l e . B e l l (1973) s u g g e s t e d t h a t t h e s e i n f l o w s were t r i g g e r e d by h i g h r i v e r run o f f and s t r o n g seaward winds ("Squamish w i n d s " ) . A p r e l i m i n a r y c o n d i t i o n f o r t h i s , o f c o u r s e , i s t h a t the o u t s i d e w a t e r found n e a r the s i l l l e v e l has t o be as dense a s , o r d e n s e r t h a n t h e Deep Water o f t h e I n n e r B a s i n . These c o n d i t i o n s a r e most l i k e l y t o be met i n e a r l y w i n t e r . D u r i n g June and J u l y 1973, B u c k l e y (1977) s t u d i e d t h e S u r f a c e L a y e r o f Howe Sound w i t h n e a r s u r f a c e p r o f i l e s o f t e m p e r a t u r e and s a l i -n i t y and w i t h r a d a r t r a c k e d s u r f a c e drogues. He f o u n d t h a t t h e d e p t h o f t h e h a l o c l i n e v a r i e d between 0 and 5 m d u r i n g h i s e x p e r i m e n t . The h a l o c l i n e was s h a r p e s t n e a r t h e mouth o f the r i v e r and more d i f f u s e f u r t h e r away. I t s depth v a r i e d w i t h t i m e , l o n g i t u d i n a l and l a t e r a l p o s i t i o n s . The b u l k o f B u c k l e y ' s e x p e r i m e n t was made w i t h drogues w i t h s a i l s s e t between 0 and 2 m. He found t h a t t h e r i v e r d i s c h a r g e f o l l o w e d a meandering p a t t e r n o v e r t h e i n l e t . D u r i n g a s h o r t e x p e r i m e n t , 8 B u c k l e y used drogues w i t h s a i l s s e t a t d i f f e r e n t d e p t h s . He fo u n d b o t h an o u t f l o w and a s t r o n g r e t u r n f l o w w i t h t h e i r c o r e s i n t h e upper 5 m. The c o r e s were l o c a t e d on d i f f e r e n t s i d e s o f the i n l e t . B u c k l e y t h e n examined the n e a r s u r f a c e c u r r e n t meter r e c o r d s and found t h a t a t 3 m, the c u r r e n t was on aver a g e g o i n g down i n l e t a t 3.6 cm/sec w h i l e a t 5 m, i t was on aver a g e g o i n g up i n l e t a t 4.2 cm/sec and a t 10 m, t h e r e were l a r g e f l u c t u a t i o n s c e n t e r e d n e a r z e r o v e l o c i t y . B u c k l e y f ound t h a t n e a r t h e head o f t h e i n l e t , w i n d s , t i d e s and v a r i a t i o n s i n t h e r i v e r d i s c h a r g e a c c o u n t e d f o r v a r i a t i o n s i n the v e l o c i t y f i e l d w h i c h had comparable m a g n i t u d e s . F u r t h e r down the i n l e t , i t was the wind w h i c h dominated the c i r c u l a t i o n o f the S u r f a c e L a y e r . The c u r r e n t meter s t r i n g e s t a b l i s h e d by the P a c i f i c Oceano-g r a p h i c Group i n t h e I n n e r B a s i n o f Howe Sound had 6 mete r s l o c a t e d i n the upper 30 m and o n l y one meter below t h i s , a t 150 m. The s p e c t r a l v a r i a n c e o f t h e c u r r e n t r e c o r d s was c o n c e n t r a t e d i n t h e band o f one t o two c y c l e s p e r day ( B u c k l e y , 1977). B u c k l e y showed t h a t a t i d a l p r i s m 2 2 model y i e l d e d a r a t i o o f t h e d i u r n a l v e l o c i t y v a r i a n c e (m /sec ) t o the s e m i - d i u r n a l v a r i a n c e o f 0.31. The c u r r e n t meter a t 150 m y i e l d e d a r a t i o o f 0.30. The o t h e r c u r r e n t m e t e r s , l o c a t e d i n the upper 30 m, had r a t i o s w h i c h were q u i t e v a r i a b l e b u t alw a y s l a r g e r t h a n 0.7. By e x a m i n i n g the shape o f t h e s p e c t r a , B u c k l e y c o n c l u d e d t h a t t h e e f f e c t o f w inds d e c r e a s e d w i t h depth and became i n s i g n i f i c a n t a t 150 m. Winds o v e r Howe Sound have a s t r o n g d i u r n a l component w h i c h would e x p l a i n why t h e r a t i o o f d i u r n a l t o s e m i - d i u r n a l v a r i a n c e i s l a r g e r n e a r the s u r f a c e . 9 The c u r r e n t meter l o c a t e d a t 150 m r e c o r d e d r o u t i n e l y v e l o c i -t i e s o f 0.15 m/sec. I n t h e c u r r e n t v e c t o r diagrams p r e s e n t e d by B e l l ( 1 9 7 3 ) , d u r i n g November and December 1973, t h e r e was a c o n s i s t e n t r e s i d u a l c u r r e n t o f the o r d e r o f .01 m/sec ( r o u g h l y 1 km/day) f l o w i n g towards t h e s i l l . D u r i n g J a n u a r y and F e b r u a r y 1974, no such c o n s i s t e n t d r i f t was f o u n d . N o t i c e t h a t t h e c u r r e n t meter i s l o c a t e d 80 m below maximum s i l l d e p t h . I t i s n o t c l e a r whether t h e r e s i d u a l c u r r e n t i s r e a l o r whether i t i s an a r t i f a c t o f t h e c u r r e n t meter and i t s m o o r i n g . 10 C h a p t e r I I New A s p e c t s o f t h e Oc e a n o g r a p h i c and C u r r e n t M e t e r D a t a . B e l l ( 1 9 7 3 ) , P i c k a r d (1975) and B u c k l e y (1977) have been c o n c e r n e d m o s t l y w i t h t h e Deep Water (below s i l l d e p t h , i n t h e I n n e r B a s i n ) and the S u r f a c e L a y e r o f Howe Sound. However, much of t h e te m p e r a t u r e m i c r o s t r u c t u r e i n f o r m a t i o n w h i c h has been o b t a i n e d i n Howe Sound comes fr o m t h e d e p t h range o f 10 t o 100 m. Moreover, much o f the d a t a were o b t a i n e d i n November 1973 e i t h e r d u r i n g o r s h o r t l y a f t e r a Deep Water r e n e w a l . B o t h t h e 10 t o 100 m d e p t h range and t h e Deep Water r e n e w a l o f the f a l l o f 1973 have r e c e i v e d l i t t l e a t t e n t i o n e a r l i e r . T h i s c h a p t e r p r e s e n t s and d i s c u s s e s some d a t a r e l e v a n t t o t h e s e a s p e c t s o f t h e p h y s i c a l oceanography o f Howe Sound. I I . 1 The I n t e r m e d i a t e Water. The o b j e c t o f t h i s s e c t i o n i s t o show b r i e f l y t h a t t h e r e a r e r e g i o n s i n Howe Sound where the e v o l u t i o n o f o c e a n o g r a p h i c p r o p e r t i e s i s c o n t r o l l e d m a i n l y by h o r i z o n t a l exchanges between t h e S t r a i t o f G e o r g i a , the Ou t e r B a s i n and the I n n e r B a s i n . F o r t h e pu r p o s e o f t h i s s t u d y , t h e w a t e r found i n t h e s e r e g i o n s i s c a l l e d t h e " I n t e r m e d i a t e Water". The d a t a p r e s e n t e d h e r e come from t h e m o n t h l y o c e a n o g r a p h i c c r u i s e s made by the I n s t i t u t e o f Oceanography o f t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a between 1972 and 1974 (I.O.U.B.C., 1972, e t c . ) . F i g u r e 4 shows the t e m p e r a t u r e t i m e - s e r i e s o b s e r v e d a t 100 m and below a t s t a t i o n s Howe 2 and Howe 3 i n t h e Ou t e r B a s i n . F i g u r e 5 p r e s e n t s t i m e s e r i e s o f t e m p e r a t u r e and s a l i n i t y f r o m each b a s i n a v e r -aged between 20 and 75 m. The s t a t i o n s a r e Howe 3 (O u t e r B a s i n ) and Howe 4.5 ( I n n e r B a s i n ) (see f i g . 1 ) . The samples from 20, 30, 50 and 75 m were a v e r a g e d w i t h w e i g h t s o f 2, 3, 4, 4 t o r e f l e c t t he s i z e o f the depth i n t e r v a l r e p r e s e n t e d by each v a l u e . F i g u r e 6 p r e s e n t s t h e t i m e - s e r i e s o f t e m p e r a t u r e , s a l i n i t y , s i g m a - t and d i s s o l v e d oxygen o b t a i n e d a t 100 m and below i n t h e I n n e r B a s i n (Howe 4.5). F i g u r e 4 shows l a r g e v a r i a t i o n s o f t e m p e r a t u r e on a t i m e s c a l e w h i c h i s w e l l r e s o l v e d by t h e m o n t h l y r a t e o f s a m p l i n g . The v a r i a t i o n s a r e a r e f l e c t i o n o f . t h o s e t a k i n g p l a c e i n the S t r a i t o f G e o r g i a ( P i c k a r d , 1975) and i l l u s t r a t e t h e r e l a t i v e l y f r e e exchanges t a k i n g p l a c e between the S t r a i t o f G e o r g i a and t h e Ou t e r B a s i n , m a i n l y t h r o u g h t h e Queen C h a r l o t t e C h a n n e l . I n f i g u r e 5, the t e m p e r a t u r e t i m e - s e r i e s show t h a t t h e v a r i a -t i o n s w h i c h o c c u r between 20 and 75 m i n b o t h b a s i n s f o l l o w a p a t t e r n s i m i l a r t o t h a t w h i c h i s o b s e r v e d below 100 m i n t h e O u t e r B a s i n . The range o f t h e t e m p e r a t u r e v a r i a t i o n s a t Howe 4.5 ( I n n e r B a s i n ) i s s l i g h t l y s m a l l e r t h a n t h a t a t Howe 3 (Outer B a s i n ) b u t no s i g n i f i c a n t l a g i s o b s e r v e d between the two t i m e - s e r i e s . The two s a l i n i t y t i m e -s e r i e s o f f i g . 5 a l s o t r a c k each o t h e r q u i t e c l o s e l y . I n s e v e r a l i n s t a n c e s , l a r g e changes i n s a l i n i t y a r e o b s e r v e d i n b o t h b a s i n s by t h e same c r u i s e s and t h u s t h e y may o c c u r w i t h i n a t i m e i n t e r v a l s h o r t e r t h a n one month. Only i n f l o w s o f s a l i n e w a t e r may r e s u l t i n i n c r e a s e s i n s a l i n i t y and, i n Howe Sound, o n l y t h e S t r a i t o f G e o r g i a may p r o v i d e t h i s s a l i n e w a t e r . Thus t h e v a r i a t i o n s i n s a l i n i t y and t e m p e r a t u r e o b s e r v e d above 75 m i n b o t h b a s i n s r e s u l t f r o m exchanges w i t h t h e S t r a i t o f G e o r g i a w h i c h can t a k e p l a c e on a time s c a l e s m a l l e r t h a n one month. I n f i g u r e 6, t h e t i m e - s e r i e s o f t e m p e r a t u r e , s a l i n i t y , s i g m a - t and d i s s o l v e d oxygen a t 125 m and below show p e r i o d s of s t e a d y t r e n d s e p a r a t e d by p e r i o d s o f l a r g e r and more a b r u p t change. T h i s p a t t e r n i s d e s c r i b e d as " s a w - t o o t h " by P i c k a r d ( 1 9 7 5 ) . B e l l (1973) showed t h a t i t c o r r e s p o n d s t o p e r i o d s when d i f f u s i v e p r o c e s s e s dominate and t o p e r i o d s when t h e r e a r e i n f l o w s f r o m t h e O u t e r B a s i n , o v e r t h e s i l l and i n t o t h e I n n e r B a s i n ' s Deep Water. T h i s p a t t e r n d i f f e r s m a r k e d l y from t h e one w h i c h was o b s e r v e d i n f i g . 4 and 5, f o r t h e O u t e r B a s i n and t h e p a r t of t h e I n n e r B a s i n a t 75 m and above. The p r e c e d i n g d i s c u s s i o n shows t h a t the I n t e r m e d i a t e Water, as d e f i n e d i n t h e f i r s t p a r a g r a p h o f t h i s s e c t i o n , i s found between about 20 m and t h e bottom i n t h e O u t e r B a s i n . I n t h e I n n e r B a s i n , i t i s chosen t o p u t t h e l o w e r l i m i t o f t h e I n t e r m e d i a t e Water a t 100 m s i n c e i n f i g . 6, t h e w a t e r a t 100 m had an e v o l u t i o n m a r k e d l y d i f f e r e n t from t h e w a t e r a t 125 m and below. The w a t e r a t 125 m and below i n the I n n e r B a s i n i s t h e r e f o r e c a l l e d the "Deep Water" i n t h i s t h e s i s . Near t h e s u r f a c e , i t i s n o t c l e a r a t what d e p t h exchanges w i t h the S t r a i t o f G e o r g i a become l e s s i m p o r t a n t t h a n t h e v e r t i c a l t u r b u l e n t t r a n s f e r o f t h e l o c a l f r e s h w a t e r r u n o f f . B u c k l e y showed t h a t , i n June 1973, most o f the f r e s h w a t e r was f o u n d i n t h e upper 10 m. Thus t h e upper l i m i t o f t h e I n t e r m e d i a t e Water may be s e t a t 10 m below t h e s u r f a c e f o r t h e purpose o f t h i s s t u d y . F i g u r e 7 p r e s e n t s a l o n g - c h a n n e l s e c t i o n o f Howe Sound where t h e S u r f a c e L a y e r , the I n t e r m e d i a t e Water and t h e Deep Water a r e shown. I I . 2 A Deep Water r e n e w a l i n the F a l l o f 1973. I n t he F a l l o f 1973, a Deep Water r e n e w a l o c c u r r e d i n the I n n e r B a s i n o f Howe Sound. On November 20 and 21, 1973 a c r u i s e made te m p e r a t u r e m i c r o s t r u c t u r e o b s e r v a t i o n s i n t h e I n n e r B a s i n . The i n t e r p r e t a t i o n o f the r e s u l t i n g d a t a ( p r e s e n t e d i n t h e n e x t c h a p t e r s ) r e q u i r e s t h a t some o f t h e i n f o r m a t i o n a v a i l a b l e f o r t h e Deep Water r e n e w a l be examined f i r s t . F i g u r e s 8, 9 and 10 p r e s e n t l o n g - c h a n n e l s e c t i o n s o f temper-a t u r e , s a l i n i t y and d i s s o l v e d oxygen (D.0.) o b t a i n e d w i t h b o t t l e c a s t s on September 20, 1973, on November 13, 1973 and on J a n u a r y 22, 1974 (I.O.U.B.C., 1973). F i g u r e 11 p r e s e n t s t h e t e m p e r a t u r e r e c o r d and the N-S component o f the v e l o c i t y r e c o r d o b t a i n e d a t 150 m by a c u r r e n t meter c h a i n l o c a t e d n e a r s t a t i o n Howe 4, f o r the p e r i o d o f O c t o b e r 25 t o November 15. P o s i t i v e c u r r e n t v a l u e s i n f i g . 11 i n d i c a t e a n o r t h -ward f l o w . N o r t h l i e s a p p r o x i m a t e l y i n an u p - i n l e t d i r e c t i o n ( f i g . l ) . The Deep Water d i s t r i b u t i o n o f September 20, 1973 ( f i g . 9 ) i s t y p i c a l o f t h a t w h i c h was e n c o u n t e r e d d u r i n g the p r e v i o u s s i x months (I.O.U.B.C., 1973). I t i s i n t e r e s t i n g t o n o t i c e t h a t the l o w e s t D.O. v a l u e s a r e f o u n d a l o n g t h e bottom p r o f i l e r a t h e r t h a n any o t h e r i s o -p l e t h . A l s o , a l o n g a same d e p t h l e v e l , c o n t r a s t s o f up t o 0.09 C° and 0.009 °/oo a r e f o u n d i n t h e b o t t l e c a s t d a t a ( I.O.U.B.C, 1973). They a r e of o p p o s i n g s i g n and no m e a s u r a b l e d e n s i t y d i f f e r e n c e r e s u l t s from them. A t e m p e r a t u r e minimum i s f o u n d a t 100 m ( f i g . 8 ) . The m o n t h l y c r u i s e s show t h a t t h e t e m p e r a t u r e a t 100 m has s t a y e d i n the v i c i n i t y o f 7.9 t o 8.0 °C s i n c e t h e p r e v i o u s June w h i l e t h e temp-e r a t u r e a t 75 m changed from c o o l e r t o warmer th a n t h i s ( I . O . U . B . C , 1973). A t 125 m and b e l o w , the t i m e - s e r i e s i n d i c a t e t h a t no l a r g e or a b r u p t change i n p r o p e r t y has o c c u r r e d (see f i g . 6 ) s i n c e the p r e v i o u s F e b r u a r y . The November 13, 1973 Deep Water d i s t r i b u t i o n ( f i g . 9 ) d i f f e r s m a r k e d l y from t h a t o f September. The I n n e r B a s i n i s now o c c u p i e d by two d i s t i n c t w a t e r masses. One mass o c c u p i e s the d e p t h range of 50 t o 200 m i n the u p - i n l e t p a r t o f t h e b a s i n . I t has the same o c e a n o g r a p h i c p r o p e r t i e s as the w a t e r w h i c h was p r e v i o u s l y f ound i n the d e e p e s t p a r t s o f the I n n e r B a s i n ( c o l d e r t h a n 8.3 C, l e s s s a l i n e t h a n 30.5 /oo and w i t h D.O. c o n c e n t r a t i o n s s m a l l e r t h a n 2.5 m l / 1 ) . T h i s w a t e r i s now c a l l e d t h e " O l d Water". The o t h e r w a t e r mass i s f o u n d below 200 m and above 50 m t h r o u g h the I n n e r B a s i n . A t Howe 4, towards t h e s i l l and i n the O u t e r B a s i n , i t o c c u p i e s t h e whole w a t e r column ( I.O.U.B.C, 1973). I t s p r o p e r t i e s a r e d i s t i n c t l y d i f f e r e n t from t h o s e o f the O l d Water and i t i s now c a l l e d the "New Water" ( t e m p e r a t u r e h i g h e r t h a n 8.5 °C, s a l i n i t y h i g h e r t h a n 30.5 °/oo, D.O. c o n c e n t r a t i o n h i g h e r t h a n 2.4 m l / 1 ) . The s i g m a - t v a l u e of b o t h w a t e r masses i s between 3 23.67 and 23.70 kg/m and t h e d e n s i t y s t r a t i f i c a t i o n b e l o w 100 m i s too s m a l l t o be a c c u r a t e l y e s t i m a t e d . The J a n u a r y 22, 1974 Deep Water d i s t r i b u t i o n ( f i g . 1 0 ) s t i l l p r e s e n t s two d i s t i n c t w a t e r masses. T h i s shows p a r t i c u l a r l y w e l l i n t h e D.O. d i s t r i b u t i o n . The c o n t r a s t between t h e two w a t e r masses i s s m a l l e r t h a n i n November ( f i g . 9 ) . The t e m p e r a t u r e d i f f e r e n c e between th e two c o r e s has d e c r e a s e d f r o m 0.5 C° t o 0.3 C° and t h e s a l i n i t y d i f f e r e n c e has d e c r e a s e d from 0.10 °/oo t o 0.08 °/oo. A t d e p t h s o f 100 m and l e s s , t h e s a l i n i t y v a l u e s a r e l o w e r t h a n i n J a n u a r y and t h e D.O. v a l u e s a r e h i g h e r , i n d i c a t i n g t h a t exchanges have been c o n t i n u i n g a t t h a t l e v e l . I n the c u r r e n t meter c h a i n l o c a t e d n e a r s t a t i o n Howe 4 d u r i n g t h e Deep Water r e n e w a l , t h e 150 m c u r r e n t meter was t h e o n l y one i n s t a l l e d below 30 m. B u c k l e y (1977) , u s i n g o n l y t h e v e l o c i t y r e c o r d o f t h i s m eter, deduced t h a t t h e Deep Water i n f l o w t o o k p l a c e e s s e n t i a l l y between November 9 and 13. D u r i n g t h i s p e r i o d , t h e p r o -g r e s s i v e v e c t o r diagrams ( B e l l , 1975) show a n e t u p - i n l e t c u r r e n t i n s t e a d o f t h e u s u a l d o w n - i n l e t " d r i f t " w h i c h was m entioned e a r l i e r i n t h i s c h a p t e r . F i g . 11 p r e s e n t s t h e N-S component o f t h e c u r r e n t v e l o c i t y and t h e t e m p e r a t u r e r e c o r d o b t a i n e d f r o m t h e c u r r e n t meter l o c a t e d a t 150 m. F i g u r e 11 shows t h a t , s t a r t i n g O c t o b e r 27, t h e r e a r e warm w a t e r " p u l s e s " o c c u r r i n g once a day a t 150 m u n t i l O c t o b e r 31. The o n l y p o s s i b l e s o u r c e of w a t e r warmer t h a n 8.4 C i s c l e a r l y New Water coming from t h e Outer B a s i n ( f i g . 8 and 9 ) . Thus, f i g . 11 shows t h a t the Deep Water r e n e w a l s t a r t e d b e f o r e o r on O c t o b e r 27. I t i s n o t c l e a r whether t h e warm w a t e r was a d v e c t e d h o r i z o n t a l l y o r v e r t i c a l l y p a s t t h e c u r r e n t meter and no e s t i m a t e o f t h e volume of t h e i n f l o w can be made from t h e c u r r e n t meter r e c o r d s a l o n e . S t a r t i n g November 2, t h e 150 m c u r r e n t meter becomes predom-i n a n t l y immersed i n warm w a t e r . The c u r r e n t v e l o c i t y shows l a r g e r v a r i a t i o n s t h a n p r e v i o u s l y and o f t e n p r e s e n t s a s o r t o f " s q u a r e wave" p a t t e r n . The r e a s o n s f o r t h i s a r e n o t c l e a r . One can s p e c u l a t e t h a t f u r t h e r i n f l o w s a r e o c c u r r i n g a t t h a t t i m e , b u t one can a l s o s p e c u -l a t e t h a t t h e Deep Water i s r e s p o n d i n g t o a c h a n g i n g p a t t e r n of f o r c i n g f u n c t i o n s ( s u r f a c e w i n d s , t i d e s , r i v e r r u n o f f ) and t h a t the 150 m c u r r e n t meter has become immerged p r e d o m i n a n t l y i n New Water as a r e s u l t o f t h i s r a t h e r t h a n as a r e s u l t o f new i n f l o w s . I n summary, the o c e a n o g r a p h i c t i m e - s e r i e s show t h a t a Deep Water r e n e w a l o c c u r r e d between September and November 1973. The c u r r e n t meter t e m p e r a t u r e r e c o r d a t 150 m i n d i c a t e s t h a t t h e r e n e w a l had a t l e a s t s t a r t e d on O c t o b e r 27. The c u r r e n t meter v e l o c i t y r e c o r d i s of l i t t l e use. The New Water o c c u p i e s t h e l o w e r 200 m o f th e Deep Water and, n e a r t h e c e n t e r o f t h e c h a n n e l , t h e p a r t o f t h e I n n e r B a s i n l o c a t e d between Howe 4 and t h e s i l l . Some of the temper-a t u r e m i c r o s t r u c t u r e d a t a w h i c h a r e p r e s e n t e d i n t h e f o l l o w i n g c h a p t e r s were o b t a i n e d s h o r t l y a f t e r November 18, 1973. I t i s now c l e a r t h a t t h e s e d a t a were o b t a i n e d a f t e r t h e b u l k o f t h e Deep Water r e n e w a l had t a k e n p l a c e . C h a p t e r I I I M i c r o s t r u c t u r e methods and d a t a p r o c e s s i n g . I I I . l P r o b e s and r e s o l u t i o n . I n t h e c o u r s e o f p r e v i o u s work i n m i c r o s t r u c t u r e , t h e need has o f t e n been f e l t f o r a s e t o f l i g h t , s i m p l e and rugged t e m p e r a t u r e m i c r o s t r u c t u r e p r o f i l e r s . The f i r s t m o t i v a t i o n i n u s i n g s u c h p r o b e s was t o i n v e s t i g a t e t h e h o r i z o n t a l c h a r a c t e r i s t i c s o f t e m p e r a t u r e m i c r o s t r u c t u r e by making s i m u l t a n e o u s p r o f i l e s . T h i s was d i f f i c u l t t o do w i t h e a r l i e r o r more complex i n s t r u m e n t s . The d e s i g n of l i g h t t e m p e r a t u r e m i c r o s t r u c t u r e p r o f i l e r s was i n i t i a t e d i n 1972 a t the U n i v e r s i t y o f B r i t i s h C o l u m b i a and r e s u l t e d i n a s e t o f t h r e e i d e n t i c a l p r obes nicknamed "Pumpkin" f o r t h e orange s p h e r i c a l f l o a t s w h i c h p r o v i d e s t h e i r buoyancy. The p r o b e s a r e d e s c r i b e d i n d e t a i l i n Osborn (1977). A s c h e m a t i c d r a w i n g o f one i s shown i n f i g . 12. The probes p r o v i d e a s u p p o r t f o r a t h e r m i s t o r b r i d g e and i t s e l e c t r o n i c s . The t h e r m i s t o r i s a m e t a l oxyde m i c r o b e a d w i t h a t y p i c a l d i a m e t e r of 150 m i c r o n s , c o a t e d w i t h a f i l m o f P a r a l e n e - C w i t h a t h i c k n e s s o f about 15 m i c r o n s f o r e l e c t r i c a l i n s u l a t i o n ( f i g . 1 2 ) To r e d u c e the o c c u r r e n c e of e l e c t r i c a l l e a k s i n t o sea w a t e r , t h e t h e r m i s t o r s u p p o r t arms ( n o t the m i c r o b e a d s ) were c o a t e d w i t h g l y p t o l . The f r e q u e n c y r e s p o n s e o f such a t h e r m i s t o r moving i n a f l u i d has been s t u d i e d by Lueck, Hertzman and Osborn ( 1 9 7 7 ) . F o r a t y p i c a l v e l o c i t y o f 20 cm/sec, t h e i r c a l c u l a t i o n s i n d i c a t e the 3 dB p o i n t i n s p a t i a l r e s o l u t i o n t o be c l o s e t o 2 cm. The p r e s e n t s t u d y c o n s i s t s o f an i n v e s t i g a t i o n o f t h e t y p e s o f f i n e s t r u c t u r e and m i c r o s t r u c t u r e f e a t u r e s e n c o u n t e r e d i n Howe Sound and o f t h e i r h o r i z o n t a l v a r i a b i l i t y . The a n a l y s i s o f the d a t a i s n o t based on q u a n t i t a t i v e e s t i m a t e s o f the t o t a l v a r i a n c e o f t h e v e r t i c a l t e m p e r a t u r e g r a d i e n t . T h e r e f o r e , t h e i n d i v i d u a l f r e q u e n c y r e s p o n s e o f each t h e r m i s t o r was n o t measured and no a t t e m p t has been made t o c o r r e c t t h e h i g h f r e q u e n c y r o l l - o f f . The t h e r m i s t o r was p a r t o f a Wheatstone b r i d g e . The e l e c t r o -n i c package o f t h e probe g e n e r a t e d a t e m p e r a t u r e s i g n a l and t h e time d e r i v a t i v e o f t h i s s i g n a l . These were r e l a y e d t o t h e s u r f a c e t h r o u g h a S i p p i c a n XWL (Exp e n d a b l e W i r e L i n k ) u s i n g IRIG FM c h a n n e l s . A t the s u r f a c e , t h e s e s i g n a l s were r e c o r d e d on tape t o be l a t e r p l a y e d back and d i g i t i z e d a t a r a t e of 250 samples p e r second p e r c h a n n e l . F o r a t y p i c a l s i n k i n g r a t e o f 20 cm/sec, t h i s c o r r e s p o n d s t o 12.5 samples p e r cm. The n o i s e p r e s e n t i n t h e s i g n a l s has been e s t i m a t e d from t h e deep p a r t s o f t h e p r o f i l e s where no m e a n i n g f u l s i g n a l c o u l d be d e t e c t e d . Most o f the n o i s e v a r i a n c e was i n t h e h i g h e r f r e q u e n c y range o f t h e i n s t r u m e n t , a t wave numbers h i g h e r t h a n 2 cm A t dept h s g r e a t e r t h a n 100 m, i t i n c r e a s e d a p p r e c i a b l y w i t h d e p t h because o f t h e i n c r e a -s i n g l e n g t h o f the XWL l i n k . Near 150 m, t y p i c a l rms n o i s e v a l u e s a r e : 0.01 C° i n t h e t e m p e r a t u r e c h a n n e l and 0.03 C°/m i n t h e g r a d i e n t c h a n n e l . D u r i n g the F e b r u a r y 1974 c r u i s e , the m i c r o s t r u c t u r e p r o b e s were used i n p a i r s . They were r e l e a s e d w i t h a h o r i z o n t a l s e p a r a t i o n o f 3, 10 and 20 m. They f e l l f r e e l y t o a de p t h o f 150 t o 200 m b e f o r e r e l e a s i n g some b a l l a s t w e i g h t and f l o a t i n g b ack t o the s u r f a c e . The p r o b e s s u r f a c e d w i t h s e p a r a t i o n s between 1 and 75 m. The s p a c i n g of t h e p r o b e s a t r e c o v e r y d i d n o t c o r r e l a t e w i t h the s p a c i n g a t l a u n c h (see T a b l e I ) . D u r i n g t h e d e s c e n t , t h e probes p r o b a b l y s t a y e d w i t h i n 3 t o 40 m of each o t h e r and t h e y r e a c h e d the de p t h o f 100 m w i t h i n one m i n u t e o f each o t h e r . I I I . 2 Method o f d a t a p r o c e s s i n g . The f i r s t s t e p i n p r o c e s s i n g the d i g i t i z e d d a t a was t o con-s t r u c t rough v e r t i c a l t e m p e r a t u r e p r o f i l e s by p l o t t i n g t h e tempera-t u r e s i g n a l v e r s u s t i m e . These p r o f i l e s were t h e n compared w i t h p r o -f i l e s o f t e m p e r a t u r e v e r s u s d e p t h o b t a i n e d a t the same l o c a t i o n w i t h a B i s s e t t - B e r m a n 9060 s e l f - c o n t a i n e d STD r e c o r d e r . S a l i e n t f e a t u r e s o f t h e p r o f i l e s were matched and t h e i r d e p t h s and t e m p e r a t u r e s on the STD c h a r t were n o t e d . By assuming t h e Pumpkin s i n k i n g r a t e t o be c o n s t a n t , the matched f e a t u r e s p r o v i d e d a d e p t h s c a l e w i t h an a c c u r a c y o f ± 3 m (± 5 %•).' When t h e Pumpkins had been used i n p a i r s , t h e a n a l y s i s r e q u i r e d y e t a f i n e r match of t h e de p t h s c a l e s so t h a t f e a t u r e s s m a l l e r t h a n s e v e r a l metres c o u l d be p a i r e d w i t h o u t a m b i g u i t y . F o r t h i s , two s a l i e n t f e a t u r e s o f one p r o f i l e were a s s i g n e d the same depth s as the e q u i v a l e n t f e a t u r e s on the o t h e r p r o f i l e o f t h e p a i r and t h e de p t h s c a l e was r e c o n s t r u c t e d by l i n e a r i n t e r p o l a t i o n . The r e s i s t a n c e o f t h e t h e r m i s t o r s d e c r e a s e s a p p r o x i m a t e l y e x p o n e n t i a l l y when t e m p e r a t u r e i n c r e a s e s . The e x p o n e n t i a l c o e f f i -c i e n t o f t h i s r e s p o n s e was known and i t was used t o g e t h e r w i t h t h e matched f e a t u r e s o f t h e STD p r o f i l e t o c o n s t r u c t a t e m p e r a t u r e c a l i -b r a t i o n w i t h an a c c u r a c y o f + 0.3 C° i n t h e range o f 6 t o 9 °C. The g a i n o f t h e d i f f e r e n t i a t o r c i r c u i t was checked by com-p a r i n g i t s s i g n a l w i t h t h e t e m p e r a t u r e s i g n a l . Then t h e t e m p e r a t u r e c a l i b r a t i o n , t h e d i f f e r e n t i a t o r c i r c u i t g a i n and t h e e s t i m a t e d s i n k -i n g r a t e were used t o s c a l e t h e d i f f e r e n t i a t e d t e m p e r a t u r e s i g n a l i n t o a v e r t i c a l t e m p e r a t u r e g r a d i e n t (°C/m) w i t h an a c c u r a c y o f + 10%. O v e r a l l p r o f i l e s : F o r c o n s t r u c t i n g o v e r a l l p r o f i l e s o f each d r o p , t h e d i g i -t i z e d t e m p e r a t u r e and g r a d i e n t d a t a were grouped i n b l o c k s o f 512 p o i n t s p e r c h a n n e l . Each b l o c k c o n t a i n e d i n f o r m a t i o n f r o m about 0.4 m o f t h e w a t e r column. F o r each b l o c k , a mean t e m p e r a t u r e , a mean t e m p e r a t u r e g r a d i e n t and a rms t e m p e r a t u r e g r a d i e n t were c a l c u -l a t e d . Each o v e r a l l p r o f i l e c o n s i s t s o f up t o 550 of t h e s e v a l u e s p l o t t e d w i t h t h e de p t h s c a l e o b t a i n e d i n t h e p r e v i o u s l y d e s c r i b e d f a s h i o n . Examples o f such p r o f i l e s a r e found i n f i g u r e s 14 t o 20. - D e t a i l e d p r o f i l e s : I t was a l s o p o s s i b l e t o p l o t t h e o r i g i n a l d i g i t i z e d s i g n a l o f t e m p e r a t u r e and g r a d i e n t s c a l e d i n °C and °C/m u s i n g t h e same c a l -i b r a t i o n method as f o r t h e o v e r a l l p r o f i l e . However, i n t h i s c a s e , b e f o r e u s i n g t h e c a l i b r a t i o n , the g r a d i e n t s i g n a l was i n t e g r a t e d i n t o a s y n t h e t i c t e m p e r a t u r e s i g n a l . T h i s was compared w i t h t h e o r i g i n a l t e m p e r a t u r e s i g n a l and t h e e f f e c t o f t h e g r a d i e n t o f f s e t was removed. Then, the new t e m p e r a t u r e s i g n a l and the g r a d i e n t s i g n a l were s c a l e d u s i n g the c a l i b r a t i o n . The s i g n a l was t h e n p l o t t e d w i t h s c a l e s o f 5 t o 1 m p e r i n c h . By t h i s method, the h i g h f r e q u e n c y n o i s e o f the t e m p e r a t u r e s i g n a l was v i r t u a l l y removed and a r e s o l u t i o n o f b e t t e r t h a n 0.005 C° o v e r s e p a r a t i o n s o f a few cm was r o u t i n e l y a c h i e v e d . Examples o f t h i s a r e found i n f i g . 21 t o 24. I I I . 3 Summary of t h e d a t a . Two c r u i s e s were made w i t h the Pumpkin m i c r o s t r u c t u r e p r o -f i l e r s i n Howe Sound. Here, the r e s u l t i n g d a t a a r e b r i e f l y p r e s e n t e d . They w i l l be d i s c u s s e d i n more d e t a i l s i n C h a p t e r s IV and V. I I I . 3 a ) The November 1973 c r u i s e : The f i r s t c r u i s e was made between November 19 and 23, 1973. Seven Pumpkin d r o p s were made. T h e i r l o c a t i o n s a r e shown i n f i g u r e 13. The r e s u l t i n g o v e r a l l p r o f i l e s a r e p r e s e n t e d i n f i g . 14 t o 20. T a b l e I I g i v e s t h e v a l u e s o f . t h e mean square t e m p e r a t u r e g r a d i e n t found i n each drop ( n o t c o r r e c t e d f o r t h e l i m i t e d r e s p o n s e o f the i n -s t r u m e n t s ) t o g e t h e r w i t h t h e l o c a t i o n and time a t w h i c h each drop was made. N o t i c e t h a t Drops P-10 and P-12 t o P-15 c o n s t i t u t e a t i m e s e r i e s o f p r o f i l e s made a t s t a t i o n Howe 4. Two d e t a i l e d p r o f i l e s from Drop P-12 and two from Drop P-13 a r e p r e s e n t e d i n f i g u r e s 21 t o 24. D u r i n g the November 1973 c r u i s e , a l a r g e number of STD c a s t s were a l s o made and t h e y r e s u l t e d i n s e v e r a l c r o s s - c h a n n e l and l o n g -c h a n n e l s e c t i o n s . One l o n g - c h a n n e l s e c t i o n i s p r e s e n t e d i n f i g . 25 and c r o s s c h a n n e l s e c t i o n s made a t Howe 4 and Howe 4.7 a r e p r e s e n t e d i n f i g . 26 and 27. I I I . 3 b) The F e b r u a r y 1974 c r u i s e : The second c r u i s e i n Howe Sound was made between F e b r u a r y 4 and 8, 1974. T h i s t i m e , b o t h b a s i n s were v i s i t e d and, f o r each d r o p , two probes were used s i m u l t a n e o u s l y . T a b l e I l i s t s a l l the drops w h i c h were made i n F e b r u a r y 1974 t o g e t h e r w i t h t h e i r t i m e and l o c a t i o n and w i t h the s e p a r a t i o n o f t h e p r o b e s a t l a u n c h and a t r e c o v e r y . F i g . 28 shows t h e l o c a t i o n o f the drops on a map o f Howe Sound. The o v e r -a l l p r o f i l e s o f t h e dro p s a r e p r e s e n t e d i n f i g . 29 t o 33. T a b l e I I I l i s t s , f o r each d r o p , the t e m p e r a t u r e change found a c r o s s t h e I n t e r -m e d i a t e Water and t h e mean square g r a d i e n t measured t h r o u g h i t ( w i t h o u t c o r r e c t i o n f o r t h e r e s p o n s e o f t h e p r o b e s ) . F i g u r e s 34 t o 37 p r e s e n t the deep p a r t o f t h e p r o f i l e s o f drops 7 t o 10 w i t h an expanded t e m p e r a t u r e s c a l e i n o r d e r t o b r i n g out the s m a l l t e m p e r a t u r e c o n t r a s t s f ound t h e r e . F i g . 38 compares STD p r o f i l e s t a k e n on J a n u a r y 22, 1974 and on F e b r u a r y 4, 1974 a t Howe 4. F i g . 39 shows a l o n g c h a n n e l STD s e c t i o n made i n the I n n e r B a s i n d u r i n g the F e b r u a r y 1974 c r u i s e and f i g . 40 shows a c r o s s - c h a n n e l s e c t i o n made a t Howe 4. C h a p t e r IV Temperature S t r u c t u r e i n Howe Sound i n November 1973 and F e b r u a r y 1974 The "Pumpkin" m i c r o s t r u c t u r e p r o f i l e r s y i e l d e d i n f o r m a t i o n about the s t r u c t u r e o f t h e d i s t r i b u t i o n o f t e m p e r a t u r e a t s c a l e s o f t e n s o f metr e s as w e l l as a t s c a l e s o f a few cm. I n t h i s c h a p t e r , t h e o v e r a l l s t r u c t u r e o f the t e m p e r a t u r e d i s t r i b u t i o n i n Howe Sound i s examined by means o f l o n g - c h a n n e l and c r o s s - c h a n n e l s e c t i o n s o f te m p e r a t u r e p r o f i l e s . Much o f the s t r u c t u r e s r e v e a l e d by t h e p r o f i l e s b e l o n g t o what G a r g e t t (1976) c a l l s t he " f i n e s t r u c t u r e " o f tempera-t u r e (see a l s o s e c t i o n 1.1). S e c o n d l y , t h e rms g r a d i e n t p r o f i l e s p r o v i d e a crude way of t a k i n g some i n f o r m a t i o n from t h e s c a l e s o f m i c r o s t r u c t u r e and p u t t i n g i t i n t o t h e l a r g e r s c a l e p i c t u r e p r o v i d e d by t h e t e m p e r a t u r e p r o f i l e s . IV.1 Temperature s t r u c t u r e i n November 1973. S i x Pumpkin o v e r a l l p r o f i l e s ( f i g . 14 t o 2 0 ) , one l o n g - c h a n n e l s e c t i o n ( f i g . 2 5 ) and two c r o s s - c h a n n e l STD s e c t i o n s ( f i g . 26 and 27) a r e used h e r e t o show the d i s t r i b u t i o n o f t e m p e r a t u r e and rms tempera-t u r e g r a d i e n t i n the I n n e r B a s i n o f Howe Sound i n November 1973. B o t t l e c a s t d a t a c o l l e c t e d on November 13, 1973 ( f i g . 9) showed t h a t the w a t e r p r e s e n t b e f o r e t h e r e n e w a l , c a l l e d O l d Water, had t e m p e r a t u r e s l o w e r t h a n 8.4 °C w h i l e the r e c e n t l y a r r i v e d w a t e r , c a l l e d New Water, had t e m p e r a t u r e s o f 8.6 °C o r more. A t s t a t i o n Howe 3.8, j u s t i n s i d e t he s i l l , t h e Pumpkin drop P - l l was made on November 21, 1973 ( p r o f i l e i n f i g . 1 5 , l o c a t i o n i n f i g . 1 3 ) . Below 20 m, t e m p e r a t u r e s between 8.6 and 8.8 °C a r e found o v e r t h e whole p r o f i l e , i n d i c a t i n g t h a t New Water i s p r e s e n t t h e r e . Between 20 and 80 m, t h e r e a r e many l a y e r s o f v a r y i n g t e m p e r a t u r e w i t h t h i c k n e s s e s o f 1 t o 10 m. A t s t a t i o n Howe 4, a c r o s s - c h a n n e l STD s e c t i o n was made ( f i g . 2 6 ) . The p r o f i l e made on t h e s o u t h - e a s t e r n s i d e o f t h e c h a n n e l shows t e m p e r a t u r e s o f 8.6 t o 8.8 °C everywhere b e l o w 30 m, i n d i c a t i n g t h a t t h i s s i d e o f t h e i n l e t i s o c c u p i e d by New Water. The p r o f i l e made on the n o r t h - w e s t e r n s i d e o f t h e c h a n n e l shows w a t e r o f 8.3 t o 8.5 °C.between 75 and 175 m, i n d i c a t i n g t h a t O l d Water o c c u p i e s t h a t p a r t o f t h e wa t e r column. The r e s t o f t h e w a t e r column i s o c c u p i e d by New Water. The p r o f i l e made i n t h e c e n t e r o f t h e c h a n n e l a l s o shows O l d Water i n the same d e p t h range w i t h a 20 m t h i c k l a y e r o f New Water n e a r 100 m d e p t h . Drops P-10 and P-12 t o P-15 were a l s o made a t Howe 4, n e a r t h e c e n t r e o f the c h a n n e l ( f i g . 1 4 and f i g . 1 6 t o 2 0 ) . Drops P-12 t o P-15 were made a t h o u r l y i n t e r v a l s ( T a b l e I I ) . On t h e s e p r o f i l e s , i n t he depth range o f 30 t o 100 m, t h e r e a r e many t e m p e r a t u r e v a r i a -t i o n s a t s c a l e s o f 1 t o 30 m. Even the t h i c k e r " l a y e r s " o f t e n cannot be t r a c e d on two s u c c e s s i v e p r o f i l e s . I n some c a s e s , the t e m p e r a t u r e o f the " l a y e r s " a s s o c i a t e s them w i t h O l d Water o r New Water. A t s t a t i o n Howe 4.3, a n o t h e r STD c r o s s - c h a n n e l s e c t i o n was made ( n o t shown h e r e ) . I n i t , New Water was found o n l y b e l o w 200 m and above 100 m; i n between t h e r e was O l d Water. I n the STD p r o f i l e made n e a r t h e S-E s i d e o f t h e c h a n n e l , the O l d Water was found between 75 and 150 m o n l y . A t s t a t i o n Howe 4.7, one STD p r o f i l e was made on each s i d e o f t h e c h a n n e l ( f i g . 2 7 ) and Drop P-16 was made n e a r t h e S-E s i d e o f t h e c h a n n e l ( f i g . 2 0 ) . I n a l l t h e s e p r o f i l e s , New Water was a g a i n found o n l y below 200 m and above 50 m. Between 50 and 75 m, the w a t e r on the STD p r o f i l e s c o u l d n o t be r e a d i l y c l a s s i f i e d as "new" o r " o l d " . Between 30 and 75 m, the t e m p e r a t u r e p r o f i l e o f drop P-16 l o o k e d v e r y s i m i l a r t o the p r o f i l e s o b t a i n e d a t s t a t i o n Howe 4 (see f o r i n s t a n c e P-13 i n f i g . 1 9 ) . I n Drops P-10 t o P-16, two a s p e c t s o f t h e rms g r a d i e n t p r o -f i l e s s t r i k e a t f i r s t g l a n c e . F i r s t l y t h e rms g r a d i e n t o c c u r s i n " b u r s t s " o r " p a t c h e s " w h i c h appear t o be a t most a few metr e s t h i c k . S e c o n d l y , t h e r e a r e " q u i e t " r e g i o n s where, f o r up t o 50 m, v e r y l i t t l e rms g r a d i e n t i s found. The r e g i o n s w i t h l i t t l e rms g r a d i e n t o c c u r i n r e g i o n s where the t e m p e r a t u r e i s u n i f o r m w i t h d e p t h . E x a m i n a t i o n o f any o f t h e p r o f i l e s a l s o r e v e a l s t h a t some sha r p t e m p e r a t u r e changes a r e accompanied by no l a r g e rms g r a d i e n t v a l u e s and a l s o t h a t some mi n o r t e m p e r a t u r e changes (where the l o c a l mean g r a d i e n t i s perhaps weaker) show v e r y h i g h rms g r a d i e n t i n t e n s i t i e s . T a b l e I I p r e s e n t s the mean square g r a d i e n t v a l u e s found i n each drop below about 20 m. The average v a l u e f o r a l l drops i s ~*3 o 2 25 x 10 ( C/m) . The v a l u e s found i n i n d i v i d u a l d r o p s v a r y f r o m t h i s v a l u e by up t o a f a c t o r o f two. Most o f the v a r i a n c e o f t h e g r a d i e n t comes from t h e upper 100 m, i n the r e g i o n where t h e r e a r e a l s o many te m p e r a t u r e v a r i a t i o n s . Near 200 m, some drops show a t e m p e r a t u r e r i s e and p a t c h e s o f rms g r a d i e n t . U n f o r t u n a t e l y , none o f t h e probes went s i g n i f i c a n t l y deeper t h a n t h i s . On t h e STD p r o f i l e s , t h e r e i s a t r a n -s i t i o n from O l d Water t o New Water near 200 m. IV.2 Temperature s t r u c t u r e i n F e b r u a r y 1974. D u r i n g t h e second m i c r o s t r u c t u r e c r u i s e i n Howe Sound, be-tween F e b r u a r y 4 and 8, 1974, b o t h b a s i n s were v i s i t e d and each drop was made w i t h two pr o b e s i n an e f f o r t t o g a i n some i n f o r m a t i o n on t h e l a t e r a l e x t e n t o f the m i c r o s t r u c t u r e p a t c h e s . N i n e d o u b l e d r o p s were made; t h e i r p o s i t i o n , t i m e and s e p a r a t i o n o f t h e p r o b e s a t l a u n c h and r e c o v e r y a r e l i s t e d i n T a b l e I . O n l y f i v e d o u b l e p r o f i l e s a r e p r e s e n t e d h e r e . These a r e Drop 6 t o Drop 10. One STD l o n g - c h a n n e l s e c t i o n and one c r o s s - c h a n n e l STD s e c t i o n a t Howe 4 were t a k e n . a) Recent e v o l u t i o n o f w a t e r p r o p e r t i e s i n Howe Sound: F i g u r e 38 compares STD p r o f i l e s made J a n u a r y 22, 1974 and F e b r u a r y 4, 1974 (two weeks a p a r t ) i n the O u t e r B a s i n and i n the I n n e r B a s i n a t Howe 4.5. F i g . 38 shows t h a t a s i g n i f i c a n t t e m p e r a t u r e d e c r e a s e has t a k e n p l a c e above 100 m i n t h e two weeks w h i c h p r e c e d e d t h e F e b r u a r y m i c r o s t r u c t u r e c r u i s e . I n t h e I n n e r B a s i n , a s i m i l a r t e m p e r a t u r e d e c r e a s e has o c c u r r e d i n the upper 60 t o 70 m. I n t h e Deep Water, the STD p r o f i l e s r e v e a l no s i g n i f i c a n t changes i n temper-a t u r e . The d i s c u s s i o n p r e s e n t e d i n c h a p t e r I I about t h e I n t e r m e d i a t e Water i n d i c a t e s t h a t such a t e m p e r a t u r e change o c c u r r e d because t h e f o r m e r I n t e r m e d i a t e Water has been r e p l a c e d by some new, c o l d e r w a t e r I t i s i n t e r e s t i n g a t t h i s p o i n t t o m e n t i o n t h a t an oceano-g r a p h i c c r u i s e a l s o v i s i t e d Howe Sound on March 15, 1974 (I.O.U.B.C, 1974). I t r e v e a l e d t h a t no major change i n t h e o v e r a l l t e m p e r a t u r e s t r u c t u r e o f t h e w a t e r column had o c c u r r e d s i n c e t h e F e b r u a r y 1974 c r u s e . I n t h e Deep Water below 150 m, the l o w e s t t e m p e r a t u r e d i f f e r e f r o m the h i g h e s t one by 0.17 C°. T h i s compares t o 0.3 C° i n J a n u a r y 1974 and 0.5 C° i n November 1973. b) Temperature s t r u c t u r e i n t h e Ou t e r B a s i n : On F e b r u a r y 5, 1974, f o u r d o u b l e Pumpkin drops and f o u r STD c a s t s were made i n R a m i l l i e s C h a n n e l (Outer B a s i n , f i g . l ) . O n ly t h e o v e r a l l p r o f i l e o f Drop 6 has been p r o c e s s e d ( f i g . 29, l o c a t i o n shown i n f i g . 2 8 ) . The STD and Pumpkin p r o f i l e s were made s e v e r a l h o u r s a p a r t and d i f f e r o n l y a t s c a l e s o f 5 t o 10 m, n e a r t h e l i m i t o f t h e s p a t i a l r e s o l u t i o n o f the STD. I n o r d e r t o make com p a r i s o n s e a s i e r , t he rms g r a d i e n t p r o -f i l e s o f Drop 6 have been put back t o back. The t e m p e r a t u r e p r o f i l e s have been o f f s e t from each o t h e r by 1.0 C°. The l e f t rms g r a d i e n t p r o f i l e accompanies t h e l e f t t e m p e r a t u r e p r o f i l e . The Pumpkins were l a u n c h e d w i t h a s e p a r a t i o n o f 20 m. T a b l e I ( d i s c u s s e d i n C h a p t e r I I I ) i n d i c a t e s t h a t , d u r i n g the d e s c e n t , the s e p a r a t i o n o f t h e p r o b e s p r o -b a b l y s t a y e d between 10 and 40 m. Drop 6 ( f i g . 2 9 ) shows many a b r u p t t e m p e r a t u r e changes and l o c a l t e m p e r a t u r e i n v e r s i o n s w i t h r e s p e c t t o t h e main t r e n d . These were n o t v i s i b l e on the t e m p e r a t u r e p r o f i l e s o b t a i n e d w i t h the STD probe. C a r e f u l e x a m i n a t i o n o f the two t e m p e r a t u r e p r o f i l e s o f Drop 6 shows t h a t d i f f e r e n c e s between t h e two o c c u r e s s e n t i a l l y a t s c a l e s s m a l l e r t h a n 2 m ( t h e p r o f i l e s a r e made from 0.4 m a v e r a g e s ) . The p r o f i l e s o f the rms g r a d i e n t show t h a t most o f the v a r i -ance a r i s e s from a few p a t c h e s w i t h a t h i c k n e s s o f one t o t h r e e m e t r e s and w i t h i n t e n s i t i e s o f \ t o \\ C°/m (rms, u n c o r r e c t e d f o r t h e f r e -quency r e s p o n s e o f the p r o b e s ) . A l a r g e p a t c h found i n one p r o f i l e may c o r r e s p o n d t o no p a t c h a t a l l i n the o t h e r p r o f i l e ( s e e f o r i n s t a n c e n e a r 105 m). As i n the November 1973 d r o p s , r e g i o n s o f the p r o f i l e s where t h e t e m p e r a t u r e i s u n i f o r m show l i t t l e rms g r a d i e n t and, i n t he r e s t o f t h e p r o f i l e s , t h e r e i s no c l e a r r e l a t i o n s h i p between the v a l u e o f t h e rms g r a d i e n t and t h a t o f t h e l o c a l mean g r a d i e n t . The mean square g r a d i e n t a v e r a g e d o v e r the whole p r o f i l e ( n o t i n c l u d i n g t he upper 20 m) and the n e t t e m p e r a t u r e d i f f e r e n c e f o und a c r o s s i t a r e g i v e n i n T a b l e I I I . The mean sq u a r e g r a d i e n t a v e r -aged o v e r b o t h p r o f i l e s i s 26.5 x 10 ^ (C°/m)^. The mean square g r a d i e n t v a l u e o f p r o f i l e A i s about t w i c e as l a r g e as t h a t o f p r o f i l e B. F i g u r e 29 shows c l e a r l y t h a t t h i s i s due t o t h e o c c u r r e n c e o f d i f f e r e n t rms g r a d i e n t p a t c h e s i n each p r o f i l e . I n each p r o f i l e , t h r e e o r f o u r p a t c h e s can a c c o u n t f o r more th a n 90% of the g r a d i e n t v a r i a n c e . c) Temperature s t r u c t u r e i n t h e I n n e r B a s i n ' s I n t e r m e d i a t e Water: On F e b r u a r y 6, 1974, f o u r d o u b l e Pumpkin d r o p s and a number of STD p r o f i l e s were made i n the I n n e r B a s i n o f Howe Sound. Here, o n l y t h e p a r t o f t h e p r o f i l e s w h i c h comes f r o m t h e I n t e r m e d i a t e Water (10 t o 100 m, see c h a p t e r I I ) i s examined. The Deep Water i s r e s e r v e d f o r s e c t i o n d ) . Drops 7 t o 10 a r e shown i n f i g . 30 t o 33 and t h e i r l o c a -t i o n i n Howe Sound i s shown i n f i g . 2 8 . One l o n g - c h a n n e l STD s e c t i o n and one c r o s s - c h a n n e l STD s e c t i o n a r e p r e s e n t e d i n f i g . 3 9 and 40. A l l t he t e m p e r a t u r e p r o f i l e s (STD and Pumpkins) d i f f e r f rom each o t h e r m o s t l y i n the 30 t o 70 m range. They can be grouped a c c o r d -i n g t o t h e i r r e s e m b l a n c e . -Drop 7 ( f i g . 3 0 ) and STD #7 ( f i g . 4 0 ) show a l a y e r o f r e l a -t i v e l y u n i f o r m t e m p e r a t u r e bounded by two sharp t e m p e r a t u r e s t e p s . I n f i g . 3 0 , t h i s l a y e r has been l a b e l l e d " l a y e r B". STD $7 was o b t a i n e d n e a r t h e S-E s i d e o f t h e c h a n n e l a t Howe 4 w h i l e Drop 7 was a l s o o b t a i n e d a t Howe 4. -Drops 8 and 9 ( f i g . 3 1 and 32) and STD #6 and #8 ( f i g . 3 9 and 40) have a p r o f i l e where t h e " l a y e r B" does n o t show c l e a r l y . O t h e r -w i s e t h e y a r e v e r y s i m i l a r t o the p r o f i l e s o f Drop 7 and STD #7. They were o b t a i n e d a t Howe 4, ne a r the c e n t e r o f t h e c h a n n e l . -Drop 10 ( f i g . 3 3 ) and STD #5, #9, and #10 ( f i g . 3 9 and 40) have i n common a t e m p e r a t u r e " b u l g e " l a b e l l e d on Drop 10 as " l a y e r D". The higher r e s o l u t i o n of the Pumpkins shows that the "bulge" consists of a temperature maximum followed about 10 m deeper by a minimum (Drop 1 0 ) ; these seem to be made of a number of steps a few metres thick. That type of structure was found at Howe 4.7, Howe 4.5 and Howe 4 on the N-W side of the channel. The rms gradient p r o f i l e s of Drops 7 to 10 (Inner Basin Intermediate Water) share many features with those of Drop 6 (Outer Basin). Most of the gradient variance i s concentrated i n several patches. Maximum rms gradient values are 5 to 1 C°/m. Regions of uniform temperature show l i t t l e rms gradient. However, there are also several s t r i k i n g differences between the rms gradient p r o f i l e s of the Inner Basin and the Outer Basin. -The rms gradient patches are thinner and fewer i n Drops 7 to 9 than i n Drop 6. -The major rms gradient patches are c l o s e l y associated with the major temperature steps (mostly i n Drops 7 and 8 ) . -Rms gradient patches found i n one p r o f i l e of a p a i r do usually correspond to patches i n the other p r o f i l e of the p a i r as well. This i s true even for minor patches i n Drops 7 to 9. -The temperature p r o f i l e s of Drops 7 to 9 contain smaller and perhaps fewer temperature inversions (with respect to the main trend) than Drop 6. Table III presents the temperature diff e r e n c e and the mean square gradient calculated i n the Intermediate Water of each drop. The average c a l c u l a t e d from Drops 7 t o 10 i s 8.6 x 10 (C°/m) . The h i g h e s t v a l u e and t h e second l o w e s t one a r e found i n the same d o u b l e drop (Drop 8 ) . The v a l u e s found i n the I n n e r B a s i n a r e thus 2 t o 4 t i m e s s m a l l e r t h a n t h o s e f o u n d i n the Ou t e r B a s i n (no c o r r e c t i o n made i n the f r e q u e n c y r e s p o n s e ) . I n Drops 7, 8 and 9, the h i g h rms g r a d i e n t v a l u e s seem t o be c l o s e l y r e l a t e d t o t h e t e m p e r a t u r e s t e p s ( f i n e s t r u c t u r e ) . The rms g r a d i e n t p a t c h e s appear t o e x t e n d l a t e r a l l y o v e r d i s t a n c e s l a r g e r t h a n about 20 m s i n c e t h e y a r e u s u a l l y f ound on b o t h p r o f i l e s , j u s t l i k e t he t e m p e r a t u r e s t e p s t h e m s e l v e s . I n Drop 10, f u r t h e r up i n l e t , t he p i c t u r e i s more c o n f u s e d because t h e t e m p e r a t u r e p r o f i l e s r e v e a l numer-ous f i n e s t r u c t u r e l a y e r s accompanied by g r a d i e n t v a r i a n c e . Only one s u c c e s s f u l Pumpkin drop was o b t a i n e d i n t h i s t y p e o f f i n e s t r u c t u r e b u t the STD s e c t i o n s i n d i c a t e t h a t such f i n e s t r u c t u r e might have been found o v e r most of t h e i n l e t . d) Temperature s t r u c t u r e i n t h e I n n e r B a s i n ' s Deep Water: I n t h i s s e c t i o n , t h e Deep Water p a r t o f t h e Pumpkin p r o f i l e s i s examined. The Deep Water, as d e f i n e d w i t h r e s p e c t t o t h e I n t e r m e d -i a t e Water i n c h a p t e r I I , i s found i n t h e I n n e r B a s i n below 100 m. A t t h a t d e p t h , the STD p r o f i l e s show no f i n e s t r u c t u r e . The t e m p e r a t u r e s c a l e o f t h e Pumpkin has been expanded so t h a t s m a l l t e m p e r a t u r e d i f f e r e n c e s become e a s i l y d e t e c t a b l e . F i g . 3 4 t o 37 show t h e Deep Water p a r t o f Drops 7 t o 10 w i t h an expanded s c a l e o f t e m p e r a t u r e . The rms g r a d i e n t s c a l e i s the same as p r e v i o u s l y t o make com p a r i s o n s e a s i e r . I n a l l t h e Pumpkin p r o f i l e s , a s l i g h t t e m p e r a t u r e maximum i s f ound n e a r 90 t o 95 m and a s l i g h t minimum i s found n e a r 105 t o 110 m. Drops 8 and 9 s t o p n e a r 125 m. Drop 10 shows a t e m p e r a t u r e minimum n e a r 125 m and a f t e r t h i s , i t s t e m p e r a t u r e i n c r e a s e s mono-t o n i c a l l y w i t h depth u n t i l t h e end o f t h e d r o p , n e a r 170 m. I n Drop 7, t h e Deep Water t e m p e r a t u r e p r o f i l e i s v e r y s i m i l a r t o t h a t o f Drop 10, e x c e p t between 120 and 165 m. T h e r e , Drop 7 shows two l a y e r s o f w a t e r w i t h t e m p e r a t u r e s 0.035 C° warmer t h a n t h o s e o f t h e w a t e r found above o r below them a t s i m i l a r d e p t h i n Drop 10. Such l a y e r e d f i n e s t r u c t u r e where the w a t e r p r o p e r t i e s a l t e r n a t e between two t y p e s i s o f t e n d e s c r i b e d as " i n t e r l e a v i n g " , an e x p r e s s i o n w h i c h s u g g e s t s t h a t t h e r e a r e two d i s t i n c t b o d i e s o f w a t e r and t h a t t h e i n s t r u m e n t s went t h r o u g h t h e i r i r r e g u l a r boundary. The d e n s i t y d i f f e r e n c e between the two w a t e r t y p e s i s n e g l i g i b l e ; t he s a l i n i t y d i f f e r e n c e i s c l o s e t o 0.006 °/oo. I n t h e Deep Water p a r t o f Drop 7 ( f i g . 3 4 ) , s i g n i f i c a n t rms g r a d i e n t v a l u e s a r e found o n l y i n a s s o c i a t i o n w i t h t h e l a y e r e d s t r u c -t u r e . The t h i c k n e s s e s o f the p a t c h e s found by the two p r o b e s d i f f e r by about 4 m. W i t h i n t h e p a t c h e s , t h e rms g r a d i e n t i s d i f f e r e n t l y d i s t r i b u t e d i n each p r o f i l e o f t h e p a i r . D i f f e r e n c e s a r e a l s o f o u n d i n t h e p r o f i l e s o f t e m p e r a t u r e a t s c a l e s o f up t o s e v e r a l m e t r e s . I n Drop 8 ( f i g . 3 5 ) , a p a t c h o f rms g r a d i e n t 5 t o 10 m t h i c k was d e t e c t e d n e a r 100 m. On each p r o f i l e o f t h e p a i r , t he rms g r a d i e n t was d i f f e r e n t l y d i s t r i b u t e d . The p a t c h was accompanied by no remark-a b l e f i n e s t r u c t u r e f e a t u r e o f t h e t e m p e r a t u r e p r o f i l e . A t s i m i l a r d e p t h , none o f the o t h e r Pumpkin p r o f i l e s showed any s i g n i f i c a n t g r a d i e n t v a r i a n c e . Drops 9 and 10 ( f i g . 3 6 and 37) showed no r e m a r k a b l e rms g r a d i e n t p a t c h e s i n t h e Deep Water. IV.3 D i s c u s s i o n . a) An I n t e r m e d i a t e Water c i r c u l a t i o n p a t t e r n ? I n November 1973, t h e c r o s s - c h a n n e l and l o n g - c h a n n e l STD and b o t t l e c a s t s e c t i o n s showed t h a t between t h e s i l l and s t a t i o n Howe 4.5, c r o s s - c h a n n e l t e m p e r a t u r e d i f f e r e n c e s were s i m i l a r t o l o n g -c h a n n e l ones. New Water was found m o s t l y on t h e S-E s i d e o f t h e c h a n n e l and n e a r t h e s i l l . I n F e b r u a r y 1974, i n t h e range o f 30 t o 70 m, d i f f e r e n c e s i n t h e a s p e c t o f t h e t e m p e r a t u r e p r o f i l e s e n c o u n t -e r e d i n a c r o s s - c h a n n e l s e c t i o n a t Howe 4 were s i m i l a r t o t h o s e e n c o u n t e r e d i n a l o n g - c h a n n e l s e c t i o n a l o n g t h e c e n t e r o f t h e i n l e t . D a h l (1977) has o b s e r v e d a n a l o g o u s c o n t r a s t s i n O s l o f j o r d . He i n t e r p r e t e d them as an i n d i c a t i o n t h a t c u r r e n t s w i t h i n t h a t f j o r d a r e s u b j e c t t o C o r i o l i s f o r c e and t h a t t h e y appeared t o be i n g e o s t r o -p h i c e q u i l i b r i u m w i t h t he d e n s i t y f i e l d . B u c k l e y (1977) a l s o m e n t i o n e d t h a t C o r i o l i s f o r c e would e x p l a i n why t h e New Water o f November 1973 was f o u n d m o s t l y on the S-E s i d e o f t h e c h a n n e l s i n c e t h i s i s t h e " r i g h t hand s i d e " f o r w a t e r e n t e r i n g t h e I n n e r B a s i n f r o m t h e Ou t e r B a s i n . I n F e b r u a r y 1974, t h e c r o s s - c h a n n e l d i f f e r e n c e s f ound a t Howe 4 may be i n t e r p r e t e d i n t h e same f a s h i o n ( f i g . 4 0 ) . These i n t e r p r e t a t i o n s s u g g e s t t h a t a mean c o u n t e r - c l o c k w i s e c i r c u l a t i o n p a t t e r n e x i s t i n t h e I n t e r m e d i a t e Water o f t h e I n n e r B a s i n between t h e s i l l and Howe 4.5, and t h a t t h i s p a t t e r n may a c c o u n t f o r changes i n o c e a n o g r a p h i c p r o p e r t i e s w h i c h were shown t o o c c u r on time s c a l e s s h o r t e r t h a n one month ( c h a p t e r I I ) . b) The Osborn-Cox model: - O u t l i n e o f t h e Osborn-Cox model: The f i r s t e f f o r t f o r p u t t i n g t e m p e r a t u r e m i c r o s t r u c t u r e i n -f o r m a t i o n t o use i n an o c e a n o g r a p h i c model i s due t o Osborn and Cox (19 7 2 ) . I n t h i s s e c t i o n , a v e r y b r i e f a c c o u n t o f t h i s model w i l l be g i v e n . I t a p p l i e s t o r e g i o n s o f a w a t e r column where a s t e a d y mean g r a d i e n t i s fo u n d ; i n t h e Howe Sound d a t a , i t m i g h t a p p l y t o r e g i o n s o f t h e F e b r u a r y 1974 I n t e r m e d i a t e Water. The complete d e r i v a t i o n o f t h e model i s g i v e n i n Osborn and Cox (197 2 ) . The e s s e n c e o f t h e model can be d e r i v e d s t a r t i n g from t h e F o u r i e r h e a t d i f f u s i o n e q u a t i o n f o r an i n c o m p r e s s i b l e f l u i d : ^ e = ^ v 2 e ( i v . i ) where D/Dt d e n o t e s t h e " m a t e r i a l d e r i v a t i v e " o p e r a t o r and r e -p r e s e n t s t h e c o e f f i c i e n t o f m o l e c u l a r h e a t d i f f u s i v i t y . I t i s assumed t h a t r a d i a t i v e t r a n s f e r s a r e n e g l i g i b l e . N e x t , one uses t h e R e y n o l d s e x p a n s i o n o f v a r i a b l e s : u. — u. + u! u. = <u.> 1 1 1 1 1 (IV.2) E < 6 > where < > denotes t h e a v e r a g i n g made o v e r some " s u i t a b l e " time and space s c a l e . One expands e q u a t i o n (IV.1) w i t h the R e y n o l d s v a r i a b l e s , m u l t i p l i e s i t by Q' and t h e n p e r f o r m s the a v e r a g i n g . The d i v e r g e n c e of t he mean f i e l d i s assumed t o be n e g l i g i b l e and the t e m p e r a t u r e f l u c t u a t i o n s a r e t a k e n t o be homogeneously d i s t r i b u t e d . E q u a t i o n (IV.1) t h e n becomes: 9_ < e^ _2 > = _ < u f .e*> • 39 - K < ( V 0 * ) 2 > n ~. 3t 2 . 1 3 X . U ; (1) (2) (3) I n e q u a t i o n ( I V . 3 ) , term (3) i s alw a y s n e g a t i v e and i n d i c a t e s t h a t m o l e c u l a r d i f f u s i o n a l w a y s a c t s as a " s i n k " f o r t e m p e r a t u r e v a r i -ance. Term (2) r e p r e s e n t s t h e i n t e r a c t i o n s between the v e l o c i t y f l u c -t u a t i o n s and t h e t e m p e r a t u r e f i e l d and a c t s g e n e r a l l y as a " s o u r c e " o f t e m p e r a t u r e v a r i a n c e . The p r o d u c t <u^9'> c o r r e s p o n d s t o a R e y n o l d s f l u x o f h e a t . F o r t h e Osborn-Cox model, one assumes a s t e a d y s t a t e and drop s term ( 1 ) . One t h e n assumes t h a t l a t e r a l g r a d i e n t s o f t h e mean f i e l d o r l a t e r a l eddy f l u x e s a r e n e g l i g i b l e , b u t t h a t v e r t i c a l ones a r e s i g n i f i c a n t . E q u a t i o n (IV.3) t h e n r e d u c e s t o : < w'0' > 30^ = - X < ( v e ' ) 2 > (IV.4) o r , a f t e r i s o l a t i n g t h e v e r t i c a l eddy f l u x : < w'0' > = ( V 0 ' ) 2 8 6 ( I V ' 5 ) 8 Z E q u a t i o n (IV.5) p r o v i d e s an a t t r a c t i v e method f o r e s t i m a t i n g v e r t i c a l h e a t t r a n s f e r s u s i n g t e m p e r a t u r e m i c r o s t r u c t u r e o b s e r v a t i o n s p r o v i d e d t h a t t h e r e g i o n o f t h e w a t e r column where i t i s a p p l i e d r e s -p e c t s t h e a s s u m p t i o n s o f t h e model. E q u a t i o n (IV.5) can a l s o be g i v e n a shape s i m i l a r t o t h a t o f t h e h e a t d i f f u s i o n p r o blem: < w» e» > — K« || d v . 6 ) w i t h : < ( V 0 * ) 2 > and: U ~ (IV.8) (3Z) I n e q u a t i o n (IV.7) ^ i s an "eddy c o e f f i c i e n t " o f v e r t i c a l h e a t d i f -f u s i o n and P» i s c a l l e d t h e Cox Number, a n o n - d i m e n s i o n a l r a t i o w h i c h has become w i d e l y a c c e p t e d f o r d e s c r i b i n g the " i n t e n s i t y " o f tempera-t u r e m i c r o s t r u c t u r e w i t h i n a m o n o t o n i c t e m p e r a t u r e p r o f i l e . -Cox numbers i n t h e F e b r u a r y 1974 d a t a : I n t h e F e b r u a r y 1974 d a t a , t h e r e a r e two r e g i o n s of t h e w a t e r column where t e m p e r a t u r e i n c r e a s e s m o n o t o n i c a l l y w i t h d e p t h . The f i r s t one i s f o u n d between 20 and 35 m i n Drops 7 t o 10 ( f i g . 2 9 t o 33) and i t i s l a b e l l e d on Drop 7 and Drop 10 as " l a y e r A". The second r e g i o n i s a l s o found i n Drop 7 t o Drop 10 between 65 and 95 m and has been l a b e l l e d " l a y e r C". I n l a y e r A, c a l c u l a t i o n s d e r i v e d d i r e c t l y f rom the d a t a show t h a t the mean v e r t i c a l t e m p e r a t u r e g r a d i e n t i s , about 0.0135 C°/m and -3 the mean square v e r t i c a l t e m p e r a t u r e g r a d i e n t i s a t l e a s t 9 x 10 (C°/m) 2. T h i s v a l u e does n o t t a k e i n t o a c c o u n t t h e l i m i t e d s p a t i a l r e s o l u t i o n o f t h e p r o b e s and t h e Cox Number p r e s e n t e d h e r e does n o t i n c l u d e any i n f o r m a t i o n about t h e h o r i z o n t a l component o f t h e temper-a t u r e g r a d i e n t a t m i c r o s t r u c t u r e s c a l e s . I t y i e l d s : < (__£')•2 > G> > ( 8 Z ) * 50 (36) 2 OZ) I n l a y e r C, d e t a i l e d p r o f i l e s p r e s e n t e d i n c h a p t e r V w i l l show t h a t most of t h e v e r t i c a l g r a d i e n t v a r i a n c e o c c u r s a t s c a l e s w h i c h can be r e s o l v e d by the Pumpkins. Depending on how one chooses t h e a v e r a g i n g 39 i n t e r v a l and w h i c h p r o f i l e one u s e s , one o b t a i n s Cox Number e s t i m a t e s o f : 4 t o 25 The q u e s t i o n a r i s e s - can t h e s e v a l u e s be i n t e r p r e t e d as an eddy c o e f f i c i e n t o f v e r t i c a l d i f f u s i o n i n Howe Sound's I n t e r m e d i a t e Water? A number of c o n s i d e r a t i o n s have t o be t a k e n i n t o a c c o u n t . - I t i s n o t c l e a r t h a t t h e h o r i z o n t a l terms o f h e a t t r a n s p o r t can be n e g l e c t e d w i t h i n Howe Sound. S e c t i o n IV.3.a s u g g e s t s t h e o p p o s i t e . - I t i s p o s s i b l e t h a t most o f t h e v e r t i c a l t r a n s p o r t o f h e a t i s a s s o c i a t e d w i t h p r o c e s s e s g o i n g on n e a r t h e w a l l s o f t h e i n l e t o r i n c o n j u n c t i o n w i t h s t r o n g w eather e v e n t s . I n t h e s e c a s e s , t h e Osborn-Cox model s t i l l a p p l i e s on t h e c o n d i t i o n t h a t t h e t e m p e r a t u r e g r a d i e n t v a r i a n c e a s s o c i a t e d w i t h t h e s e p r o c e s s e s i s t a k e n i n t o a c c o u n t . Here, i t was n o t . -The l i m i t e d s p a t i a l r e s o l u t i o n of t h e pr o b e s r e s u l t s i n e s t i m a t e s o f t h e v e r t i c a l g r a d i e n t v a r i a n c e w h i c h a r e too low by an unknown f a c t o r . The h o r i z o n t a l component o f t h e g r a d i e n t v a r i a n c e a r e n o t o b s e r v e d . L a y e r C ( f i g . 30 and 33) p r e s e n t s an i n t e r e s t i n g p r o b l e m i n t h a t i t i s l o c a t e d m o s t l y below maximum s i l l d e p t h and i t s p r o f i l e has a shape r e m i n i s c e n t o f p r o f i l e s f o u n d i n h e a t d i f f u s i o n p r o b l e m s . One would l i k e t o v e r i f y i f an eddy d i f f u s i v i t y c o e f f i c i e n t d e r i v e d w i t h the Cox Number c o u l d be c o m p a t i b l e w i t h the f o r m a t i o n o f l a y e r C by v e r t i c a l t u r b u l e n t t r a n s p o r t o r i f h o r i z o n t a l exchanges p r o v i d e a more l i k e l y mechanism. On J a n u a r y 24, 1974, STD p r o f i l e s showed t h a t t h e w a t e r column between 50 and 100 m was n e a r l y i s o t h e r m a l ( f i g . 3 8 ) . L e t us t h e n assume t h a t between 60 and 90 m, t h e t e m p e r a t u r e was i n i t i a l l y u n i f o r m and e q u a l t o t h e t e m p e r a t u r e o f t h e w a t e r f o u n d below 90 m, and t h a t i t has been r e d u c e d by v e r t i c a l eddy d i f f u s i o n . T h i s p r o b -lem i s s i m i l a r t o t h a t o f a s e m i - i n f i n i t e medium i n c o n t a c t w i t h a c o n s t a n t t e m p e r a t u r e s o u r c e . I n t h i s p r o b l e m , 70% o f t h e t e m p e r a t u r e change o c c u r s w i t h i n a d i s t a n c e H f r o m t h e s o u r c e such t h a t : H 2 = 2 ^ t (IV.9) where ^ e i s t h e eddy c o e f f i c i e n t o f v e r t i c a l h e a t d i f f u s i o n and t i s t h e t i m e e l a p s e d s i n c e t h e c o n s t a n t t e m p e r a t u r e s o u r c e was a p p l i e d t o t h e s e m i - i n f i n i t e medium. U s i n g e q u a t i o n s (IV.8) and ( I V . 7 ) , one o b t a i n s a Cox Number o f : § = H 2 (IV.10) I n l a y e r C, the v a l u e o f H on F e b r u a r y 6, 1974 i s about 30 m (see Drops 7 t o 10, f i g . 34 t o 3 7 ) . The maximum ti m e e l a p s e d s i n c e the " c o n s t a n t t e m p e r a t u r e s o u r c e " c o n d i t i o n was a p p l i e d i s about 1.2 x 10^ sec (two weeks). U s i n g a m o l e c u l a r h e a t d i f f u s i o n -7 2 c o e f f i c i e n t o f 1.4 x 10 m / s e c we f i n d t h a t t h e v a l u e o f t h e Cox Number s h o u l d be about 2600. T h i s v a l u e i s a t l e a s t a f a c t o r o f 100 l a r g e r t h a n t h e v a l u e s r e p o r t e d e a r l i e r on t h e b a s i s of the Pumpkin d a t a . One c o n c l u d e s t h a t l a y e r C was formed p e r h a p s t h r o u g h i n t e r -m i t t e n t " c a t a s t r o p h i c " m i x i n g e v e n t s w h i c h were n o t o b s e r v e d o r , more l i k e l y , t h a t t h e shape o f t h e p r o f i l e o f l a y e r C r e s u l t s f r o m t h e a d v e c t i o n of w a t e r coming f r o m the O u t e r B a s i n and t h a t t h e shape o f the p r o f i l e does n o t r e s u l t from v e r t i c a l m i x i n g . c) A model f o r an i s o l a t e d and inhomogeneous volume of f l u i d : The Osborn-Cox model i s a p a r t i c u l a r case d e r i v e d f r o m e q u a t i o n ( I V . 3 ) . Here, a n o t h e r p a r t i c u l a r c a s e i s p r e s e n t e d because i t may be b e t t e r s u i t e d f o r a d e s c r i p t i o n o f t h e Deep Water o f Howe Sound's I n n e r B a s i n . Take a volume o f f l u i d ( w a t e r ) w h i c h has an inhomogeneous t e m p e r a t u r e d i s t r i b u t i o n and w h i c h undergoes no h e a t exchanges w i t h i t s s u r r o u n d i n g s . Then, i f a v e r a g i n g i s done o v e r t h e whole volume, t h e t r a n s p o r t ' terms o f e q u a t i o n (IV.3) can be dropped and i t becomes: _ < B — - • -K < ( v e ' ) 2 > «v.ii) 3t 2 I n t h i s c a s e , 0 ( w h i c h does n o t appear e x p l i c i t l y i n t h e e q u a t i o n ) i s t h e mean t e m p e r a t u r e w i t h i n t h e volume and i t i s e x p e c t e d t o s t a y c o n s t a n t s i n c e t h e r e a r e no h e a t exchanges between the volume and i t s s u r r o u n d i n g s . <0' 2> i s a measure of t h e i n h o m o g e n e i t y o f th e t e m p e r a t u r e f i e l d and i t i s e x p e c t e d t o d e c r e a s e w i t h t i m e due t o t h e m i x i n g e f f e c t of m o l e c u l a r d i f f u s i o n . From e q u a t i o n ( I V . 1 1 ) , one can d e r i v e a t i m e s c a l e w h i c h d e s c r i b e s t h e r a t e a t w h i c h t h e temper-a t u r e d i f f e r e n c e s w i t h i n the f l u i d a r e b e i n g d i s s i p a t e d by m o l e c u l a r p r o c e s s e s : < e* 2 > 2 % < ( V 0 1 ) 2 > ( I V ' 1 2 ) I n e q u a t i o n ( I V . 1 2 ) , t h e t e m p e r a t u r e v a r i a n c e i s an easy p a r a m e t e r t o measure, u s i n g f o r example a s t a n d a r d STD p r o b e . M e a s u r i n g the f u l l g r a d i e n t v a r i a n c e however i s a more d i f f i c u l t t a s k s i n c e a v e r y h i g h s p a t i a l r e s o l u t i o n has t o be a t t a i n e d and s i n c e t h e g r a d i e n t v a r i a n c e may o c c u r i n t e r m i t t e n t l y and a t l o c a t i o n s w h i c h a r e dangerous f o r t h e p r o b e s t o sample (nea r t h e bottom o r the s i d e s o f Howe Sound i n t h i s c a s e ) . M o r e o ver, f r e e - f a l l i n g m i c r o s t r u c t u r e p robes measure o n l y t h e v e r t i c a l component of t h e t e m p e r a t u r e g r a d i e n t . An a t t e m p t can s t i l l be made t o match some of t h e d a t a o b t a i n e d by the Pumpkins i n the Deep Water of Howe Sound and o t h e r i n f o r m a t i o n coming from o c e a n o g r a p h i c d a t a . The Deep Water o f Howe Sound appears t o have undergone no s i g n i f i c a n t change i n i t s mean t e m p e r a t u r e between November 1973 and J a n u a r y 1974. D u r i n g t h a t p e r i o d , b o t t l e c a s t measurements showed t h a t t h e maximum t e m p e r a t u r e d i f f e r e n c e f ound w i t h i n t h e Deep Water d e c r e a s e d f r o m 0.5 C° t o 0.17 C°. T h i s s u g g e s t s a m i x i n g t i m e s c a l e of about t h r e e months ( t a k i n g f o r g r a n t e d an e x p o n e n t i a l decay) and t h u s : T ^ 10^ sec The maximum t e m p e r a t u r e d i f f e r e n c e i n F e b r u a r y 1974 was p r o b a b l y c l o s e t o 0.2 C° and t h i s s u g g e s t s t h a t : < 6' 2 > 0.01 (C°) 2 E q u a t i o n (IV.10) t h e n r e q u i r e s t h a t on t h e a v e r a g e , the l e v e l o f g r a d i e n t v a r i a n c e f o u n d i n t h e Deep Water be: < ( V 0 ' ) 2 > ^ 3 x 1 0 " 3 (C°/m) 2 T h i s v a l u e i s c l o s e t o the rms n o i s e l e v e l o f t h e Pumpkin's g r a d i e n t s i g n a l . However, due t o t h e p a t c h i n e s s o f t h e g r a d i e n t v a r i -ance d i s t r i b u t i o n , such a mean v a l u e s h o u l d g i v e r i s e t o e a s i l y o b s e r -v a b l e p a t c h e s ( f r o m the p o i n t o f v i e w o f the s e n s i t i v i t y o f the i n s t r u m e n t s ) . Drops 7 and 8 ( f i g . 3 0 and 31, F e b r u a r y 1974) show p a t c h e s o f about 10 m t h i c k n e s s and w i t h mean square g r a d i e n t v a l u e s o f a t l e a s t 10 t o 20 (C°/m) 2 w i t h i n the p a t c h e s . C o r r e c t i n g f o r t h e f r e q u e n c y r e s p o n s e o f t h e p r o b e s would i n c r e a s e t h i s v a l u e ; a v e r a g i n g o v e r the Deep Water w a t e r column would r e d u c e i t a l t h o u g h o t h e r p a t c h e s c o u l d w e l l e x i s t e l s e w h e r e w i t h i n t h e Deep Water. I n terms of o r d e r s o f magnitude, i t seems t h a t the Pumpkin o b s e r v a t i o n s show some c o n s i s t e n c y w i t h t h e b o t t l e c a s t t i m e s e r i e s i n t h e Deep Water as i n t e r p r e t e d i n t h e l i g h t o f e q u a t i o n ( I V . 1 2 ) . What i s m i s s i n g now i s a more complete coverage o f t h e o c c u r r e n c e o f t e m p e r a t u r e g r a d i e n t v a r i a n c e w i t h i n t h e I n n e r B a s i n and a h i g h e r s p a t i a l r e s o l u t i o n f o r t h e p r o b e s . Chapter V V . l Introduction. This chapter presents 21 de t a i l e d p r o f i l e s of temperature microstructure obtained i n Howe Sound. They have been selected so as to present structures which are t y p i c a l of those found i n the d i f f e r e n t regions of the water column presented i n chapters T i l and IV. They are discussed i n terms of h o r i z o n t a l extent, r e l a t i o n -ship between f i n e structure and microstructure, and possible causes for t h e i r existence. When two probes have been used simultaneously, the r e s u l t -ing p r o f i l e s are shown side by side. The usual sign convention i s used to l a b e l the scale of the v e r t i c a l temperature gradient (p o s i t i v e gradient when temperature increases upwards). Notice however that, due to an inconsistency during the data processing, p o s i t i v e values are plotted on the l e f t side of zero gradient and are l a b e l l e d accordingly. 45 V.2 D e t a i l e d p r o f i l e s . A) November 1973 p r o f i l e s : F i g u r e s 21 t o 24 show segments o f Drops 12 and 13. These dr o p s were made a t s t a t i o n Howe 4 on November 21, 1973. The o v e r a l l p r o f i l e s o f Drop 12 and 13 a r e p r e s e n t e d i n f i g . 16 and 17 and the depths from w h i c h t h e d e t a i l e d p r o f i l e have been t a k e n a r e i n d i c a t e d on them. I n f i g . 21 ( f r o m Drop P-12) t h e t e m p e r a t u r e i n c r e a s e s down-wards i n two " s t e p s " o f about 0.1 and 0.15 C°. The t e m p e r a t u r e changes t a k e p l a c e o v e r v e r t i c a l d i s t a n c e s o f 0.2 t o 0.4 m. Between th e two s t e p s , t e m p e r a t u r e f l u c t u a t i o n s w i t h an rms a m p l i t u d e o f about 0.01 C° o c c u r a t s c a l e s s m a l l e r t h a n 0.1m. I t i s t h e s e s m a l l s c a l e t e m p e r a t u r e f l u c t u a t i o n s r a t h e r t h a n t h e t e m p e r a t u r e " s t e p s " w h i c h g i v e r i s e t o the f l u c t u a t i o n s o f t h e t e m p e r a t u r e g r a d i e n t . The g r a d i e n t f l u c t u a t i o n s form a " p a t c h " w h i c h e x t e n d s from one tempera-t u r e s t e p t o t h e o t h e r . W i t h i n t h e " p a t c h " , the g r a d i e n t s i g n a l r e a c h e s peak v a l u e s o f 2 C°/m o r more. The peaks a r e about e q u a l l y d i s t r i b u t e d between p o s i t i v e and n e g a t i v e v a l u e s . I n f i g . 2 2 ( a l s o from Drop P-12) t h e t e m p e r a t u r e d e c r e a s e s w i t h i n c r e a s i n g d e p t h i n an i r r e g u l a r f a s h i o n . A t t h e bottom o f t h i s d e c r e a s e , t h e r e i s a s m a l l t e m p e r a t u r e jump. As i n f i g . 2 1 , most of t h e g r a d i e n t v a r i a n c e i s a s s o c i a t e d w i t h t e m p e r a t u r e f l u c t u a t i o n s a t s c a l e s s m a l l e r t h a n 0.1m. I n t h e upper h a l f o f f i g . 2 2 , t h e peak v a l u e s o f t h e g r a d i e n t s i g n a l have m o s t l y the same s i g n as t h a t o f t h e mean g r a d i e n t . T h i s i s i n c o n t r a s t w i t h what i s seen i n t h e l o w e r p a r t of f i g . 22 and t h r o u g h o u t f i g . 21. The s m a l l t e m p e r a t u r e jump l o c a t e d n e a r t h e b ottom of f i g . 22 i s a s s o c i a t e d w i t h c o m p a r a t i v e l y l i t t l e g r a d i e n t v a r i a n c e . F i g . 23 comes from a r e g i o n o f Drop 13 w h i c h p r e s e n t s many a b r u p t t e m p e r a t u r e changes (see f i g . 1 7 ) . Near 37 m, a 0.05 C° change o c c u r s w i t h a 0.5 C°/m h i g h , 0.12 m t h i c k g r a d i e n t p u l s e . Near 38 m, a t e m p e r a t u r e change w i t h a s i m i l a r magnitude i s accompanied by a c l u s t e r o f g r a d i e n t s p i k e s p e a k i n g a t 1.5 t o 2 C°/m and w i t h t h i c k n e s s e s s m a l l e r t h a n 0.05 m. Near 38.7 m a 0.06 C° t e m p e r a t u r e s t e p i s accom-p a n i e d by a s i n g l e g r a d i e n t s p i k e w h i c h peaks a t more t h a n 3 C°/m ( t h e maximum v a l u e w h i c h c o u l d be p l o t t e d h e r e ) . I n t h e s e examples, most o f the g r a d i e n t peak v a l u e s have t h e same s i g n as t h a t of t h e l o c a l mean g r a d i e n t ( a v e r a g e d o v e r i n t e r v a l s of one o r two m e t r e s ) . F i g . 24 p r e s e n t s a r e g i o n o f Drop 13 where t h e t e m p e r a t u r e d e c r e a s e s w i t h depth i n two ramps, each about 1.5 m t h i c k , s e p a r a t e d f r o m each o t h e r by a n e a r l y i s o t h e r m a l l a y e r a l s o about 1.5 m t h i c k . F l u c t u a t i o n s i n t e m p e r a t u r e o c c u r m a i n l y a t s c a l e s o f 0.1 m o r l e s s . A t t h e s e s m a l l s c a l e s , t h e r e a r e many t e m p e r a t u r e i n v e r s i o n s ( w i t h r e s p e c t t o t h e main t r e n d ) . A l l the l a r g e g r a d i e n t peaks have t h e same s i g n as t h e mean g r a d i e n t . The mean g r a d i e n t t h r o u g h t h e ramps i s about 0.077 C°/m w h i l e t h e r.m.s. g r a d i e n t ( u n c o r r e c t e d f o r t h e l i m i t e d r e s p o n s e o f t h e p r o b e s ) i s about 0.2 C°/m, 2\ t i m e s l a r g e r . I n summary, th e m i c r o s t r u c t u r e p r o f i l e s o f November 1973 show t h a t the a b r u p t t e m p e r a t u r e changes w h i c h were seen i n t h e o v e r a l l p r o f i l e s t a k e p l a c e o v e r v e r t i c a l d i s t a n c e s of 0.1 t o 2 m e t r e s i n many c a s e s . The t e m p e r a t u r e changes o c c u r e i t h e r as a b r u p t jumps ( " s t e p s " ) , as r e g i o n s of l a r g e t e m p e r a t u r e f l u c t u a t i o n s o r as r e g i o n s where t h e d e t a i l e d p r o f i l e i s smooth and a l m o s t l i n e a r ("ramps"). The v a r i a n c e i n t h e t e m p e r a t u r e g r a d i e n t w h i c h i s o b s e r v e d i n t h e o v e r a l l p r o f i l e s may be caused by s i n g l e s p i k e s , a c l u s t e r i n g o f s p i k e s w h i c h have m o s t l y t h e same s i g n , o r p a t c h e s of f l u c t u a t i o n s where t h e g r a d i e n t has peaks about e q u a l l y d i s t r i b u t e d between p o s i t i v e and n e g a t i v e v a l u e s . The magnitude o f a t e m p e r a t u r e change seems p o o r l y r e l a t e d t o t h e magnitude of t h e g r a d i e n t v a r i a n c e t h a t goes w i t h i t , i f i t i s r e l a t e d a t a l l . B) Outer B a s i n , F e b r u a r y 1974. Three d e t a i l e d p r o f i l e s t a k e n f r o m Drop 6 ( F e b r u a r y 1974) a r e p r e s e n t e d h e r e . Drop 6 was made i n R a m i l l i e s C h a n n e l ( O u t e r B a s i n ) . I t s o v e r a l l p r o f i l e i s p r e s e n t e d i n f i g . 29 and the l o c a t i o n o f t h e d e t a i l e d p r o f i l e s i s shown on i t . F i g . 41 p r e s e n t s a l o c a l t e m p e r a t u r e maximum fo u n d n e a r a depth o f 57 m i n Drop 6. A t t h e top of t h e warmer l a y e r , t h e tempera-t u r e change t a k e s p l a c e t h r o u g h s t e p s of 0.1 t o 0.2 C°, 0.2 t o 0.5 m t h i c k . S t e p s were f o u n d by b o t h p r o b e s a l t h o u g h t h e d e t a i l s o f t h e s t e p s d i f f e r on each p r o f i l e . I n t h e g r a d i e n t s i g n a l , t h e s t e p s t r a n s l a t e i n t o s p i k e s p e a k i n g a t more th a n 3 C°/m (and i n some c a s e s a t more th a n 4.5 C°/m, t h e l i m i t o f t h e d i g i t i z e r ) . I n t h e s i g n a l , the s p i k e s a r e t h i n n e r t h a n 0.05 m. I n t h e o v e r a l l p r o f i l e o f Drop 6 ( f i g . 2 9 ) , t h e s e few s p i k e s g i v e r i s e t o one o f t h e l a r g e s t r.m.s. g r a d i e n t " p a t c h " o f t h i s d r o p . A t t h e bottom o f t h e warmer l a y e r (between d e p t h s o f 59 and 60 m, where t e m p e r a t u r e d e c r e a s e s downwards), t h e t e m p e r a t u r e p r o f i l e t a k e s t h e shape of a smooth "ramp". The g r a d i e n t s i g n a l c o n s i s t s o f " r i p p l e s " w i t h a wave l e n g t h o f about 0.05 m and an a m p l i t u d e o f about 0.2 C°/m. I n p r o f i l e B, on t h e r i g h t o f f i g u r e 41, j u s t above t h e t e m p e r a t u r e "ramp", t h e r e i s a p a t c h o f h i g h wave number g r a d i e n t f l u c t u a t i o n s . The g r a d i e n t peaks a r e about e q u a l l y d i s t r i b u t e d between p o s i t i v e and n e g a t i v e v a l u e s . The r.m.s. v a l u e of t h e g r a d i e n t i s 0.4 C°/m ( u n c o r r e c t e d ) and the p a t c h i s 0.75 m t h i c k . Y e t t h e g r a d i e n t s i g n a l i n t e g r a t e s i n t o a n e t t e m p e r a t u r e change o f o n l y 0.02 C° a c r o s s the p a t c h . I t i s i n t e r e s t i n g t o n o t i c e t h a t no such p a t c h i s found i n p r o f i l e A. F i g u r e 42 shows the d e t a i l o f a l a r g e m i c r o s t r u c t u r e p a t c h found i n Drop 6 n e a r 70 m. I n t h e o v e r a l l p r o f i l e o f Drop 6 ( f i g . 2 9 ) , t h e two p a t c h e s a r e o f f s e t i n d e p t h by about 3 m. I n f i g u r e 42, t h e t e m p e r a t u r e s t e p s have been r e a l i g n e d i n o r d e r t o f a c i l i t a t e c o m p a r i -sons. A t s c a l e s of 1 m o r l e s s , the two t e m p e r a t u r e p r o f i l e s b e a r l i t t l e r e semblance t o each o t h e r . More t e m p e r a t u r e f l u c t u a t i o n s a t s c a l e s s m a l l e r t h a n 0.1 m a r e found i n p r o f i l e A t h a n i n p r o f i l e B. The a m p l i t u d e of t h e t e m p e r a t u r e f l u c t u a t i o n s i s comparable t o t h e t e m p e r a t u r e d i f f e r e n c e f ound a c r o s s t h e " p a t c h " . The g r a d i e n t s i g n a l peaks a t v a l u e s l a r g e r t h a n 3 C /m, on b o t h s i g n s . The p a t c h of p r o -f i l e A c o n t a i n s s e v e r a l t i m e s more g r a d i e n t v a r i a n c e t h a n t h a t o f p r o f i l e B. I n f i g u r e 43, t h e l a s t p a i r o f d e t a i l e d p r o f i l e s t o be p r e s e n t e d i n Drop 6, p r o f i l e A shows a l a r g e p a t c h o f g r a d i e n t f l u c -t u a t i o n s w h i c h i s n o t f o u n d a t a l l i n p r o f i l e B. M o r e o v e r , t h e t e m p e r a t u r e p r o f i l e s a r e a l t o g e t h e r d i f f e r e n t : p r o f i l e A p r e s e n t s a t e m p e r a t u r e maximum w h i c h i s n o t found i n p r o f i l e B. The two p r o b e s were s e p a r a t e d h o r i z o n t a l l y by 10 t o 30 m and probe B, s i n k i n g s l i g h t l y s l o w e r t h a n probe A d u r i n g t h i s d r o p , r e a c h e d the d e p t h o f the p a t c h some 40 seconds l a t e r t h a n probe A. I t was n o t e d i n C h a p t e r IV t h a t t e m p e r a t u r e s t r u c t u r e s a,t s c a l e s o f 2 m o r l e s s o f t e n do n o t c o r r e s p o n d on two p r o f i l e s o f a p a i r . Here, the d e t a i l e d p r o f i l e s p r e s e n t i n s t a n c e s where t h e t y p e o f m i c r o s t r u c t u r e i s the same on b o t h p r o f i l e s ( f o r i n s t a n c e on t h e upper and l o w e r s i d e s o f t h e t e m p e r a t u r e maximum n e a r 55 m). I n o t h e r i n s t a n c e s , t h e r e were l a r g e d i f f e r e n c e s i n t h e t y p e o f m i c r o -s t r u c t u r e as w e l l as i n the amount of g r a d i e n t v a r i a n c e o b s e r v e d , f o r i n s t a n c e , n e a r 58 m. Near 105 m, a l a r g e p a t c h o f g r a d i e n t v a r i a n c e was f o u n d i n one p r o f i l e w h i l e none was f o u n d i n t h e o t h e r . A t t h a t d e p t h , s l i g h t d i f f e r e n c e s c o u l d a l s o be found i n t h e l o c a l w a t e r t y p e s . 50 C) F e b r u a r y 1974, I n t e r m e d i a t e Water ( I n n e r B a s i n ) . E l e v e n s e t s o f d e t a i l e d p r o f i l e s o b t a i n e d i n t h e I n t e r m e d -i a t e Water of t h e I n n e r B a s i n a r e p r e s e n t e d h e r e . A v a r i e t y of s t r u c t u r e s found i n Drops 7, 8 and 9 ( s t a t i o n Howe 4) can be t r a c e d from one p r o f i l e t o t h e n e x t . Drop 10 p r e s e n t s a f i n e s t r u c t u r e and a m i c r o s t r u c t u r e w h i c h i s d i f f e r e n t enough from t h a t of the o t h e r d r o p s t o d e s e r v e s p e c i a l a t t e n t i o n . Drop 7 I n the o v e r a l l p r o f i l e o f Drop 7 ( f i g . 3 0 ) , t h e r e g i o n l o c a t e d between 10 and 40 m p r e s e n t s v e r y l i t t l e g r a d i e n t v a r i a n c e . Y e t , when s m a l l p a t c h e s a r e f o u n d , t h e y show on each p r o f i l e of t h e p a i r . F i g u r e 44 comes from. 28 t o 34 m and g i v e s a c l o s e r l o o k a t t h e s e s t r u c t u r e s . I t shows t h a t d e t a i l s as s m a l l as 0.2 m i n t h e tem-p e r a t u r e p r o f i l e can be seen on b o t h p r o f i l e s (see f o r i n s t a n c e n e a r 30 m). I t i s i n t e r e s t i n g t o n o t i c e the p r e s e n c e of a number of t e m p e r a t u r e i n v e r s i o n s ( w i t h r e s p e c t t o the main t r e n d ) a t s c a l e s s m a l l e r t h a n 0.5 m. These a r e n o t n o t i c e a b l e i n t h e o v e r a l l p r o f i l e s . I t i s a l s o o f i n t e r e s t t o n o t i c e t h a t t h e g r a d i e n t peaks w h i c h g i v e r i s e t o t h e v a r i a n c e p a t c h e s a r e f o u n d where t h e r e a r e a b r u p t temper-a t u r e i n c r e a s e s ( i n the downwards d i r e c t i o n ) . F i g u r e s 45 and 46 show two a b r u p t t e m p e r a t u r e changes t h a t o c c u r i n Drop 7 n e a r 43 and 53 m (see o v e r a l l p r o f i l e ) . F i g . 45 shows t h a t each probe sensed a d i f f e r e n t m i c r o s t r u c t u r e a t t h e t e m p e r a t u r e s t e p . I n p r o f i l e A, t h e r e i s a p a t c h o f g r a d i e n t s p i k e s w i t h m o s t l y the sign as the mean gradient. In p r o f i l e B, the temperature change occurs through only two large gradient spikes. Just a few cm above i t , however, there are gradient f l u c t u a t i o n s about a zero mean. Near 4 6 m, there i s a temperature change with no s i g n i f i c a n t gradient variance. In f i g . 4 6 , the temperature steps of both probes are accom-panied by a gradient s i g n a l which consists of several spikes with magnitudes of more than 4 C°/m. Most of the temperature change occurs within 0 . 2 m. Below 5 4 m, the temperature increases i r r e g u l a r l y but monotonously downwards. The gradient s i g n a l presents no large peaks. No temperature inversion (with respect to the main trend) i s observed even at the smallest scales. Between 5 5 and 5 9 m, the mean gradient i s - 0 . 0 . 4 4 C ° / m while the r.m.s. gradient i s about 0 . 0 9 C°/m (a factor of three above the noise l e v e l ) . Figures 4 4 , 4 5 and 4 6 are t y p i c a l of three regions of Drop 7 which are outlined i n the o v e r a l l p r o f i l e to f i g . 3 0 and c a l l e d "layer A", "layer B" and "layer C". These regions of the water column are examined again i n Drops 8 and 9 . Drop 8 Two d e t a i l e d p r o f i l e s taken from Drop 8 are presented here ( f i g . 4 7 and 4 8 ) . Drop 8 was made one hour a f t e r Drop 7 and within one km of the p o s i t i o n of Drop 7 . The o v e r a l l p r o f i l e of Drop 8 shares many features with that of Drop 7 . F i g . 47 comes from 19 t o 26 m. Two main t e m p e r a t u r e changes a r e seen on each p r o f i l e ( n e a r 20 and 23.5 m). Near 20 m, a s m a l l t e m p e r a t u r e i n v e r s i o n i s a l s o o b s e r v e d i n b o t h p r o f i l e s . I n t h i s r e g i o n of the w a t e r column, t h e mean g r a d i e n t i s about 0.01 C°/m. Two t e m p e r a t u r e s t e p s a c c o u n t f o r one t h i r d t o one h a l f o f t h i s . Between t h e s t e p s , t h e mean g r a d i e n t s t a y s c l o s e t o 0.005 t o 0.001 C°/m and a number o f m i n o r t e m p e r a t u r e s t e p s s t i l l a c c o u n t f o r much of t h i s t r e n d . A t each m a j o r t e m p e r a t u r e s t e p , t h e r e i s a g r a d i e n t p u l s e . The p u l s e s a c c o u n t f o r most o f the g r a d i e n t v a r i a n c e . A t 24 m, below a g r a d i e n t p u l s e , t h e r e a r e a l s o some g r a d i e n t f l u c t u a t i o n s w h i c h form a s o r t of low a m p l i t u d e " p a t c h " on b o t h t r a c e s . F i g . 48 comes from between 50 and 58 m. I t p r e s e n t s two l a r g e t e m p e r a t u r e changes s e p a r a t e d by a l o c a l t e m p e r a t u r e maximum and a minimum. The t e m p e r a t u r e l a y e r i n g o f t h i s f i g u r e i s v e r y s i m i l a r t o t h a t w h i c h was found i n Drop 7 a t s i m i l a r d e p t h (see f i g . 45 and 4 6 ) . What i s m i s s i n g h e r e i s a n e a r l y i s o t h e r m a l l a y e r w h i c h , i n Drop 7, was f o u n d between 47 and 52 m ( t h e t e m p e r a t u r e minimum). G r a d i e n t s p i k e s a r e found as i n Drop 7. H e r e , most of t h e t e m p e r a t u r e changes o c c u r w i t h i n one metre i n s t e a d of 0.2 m i n Drop 7. N o t i c e t h a t t h e t e m p e r a t u r e s t e p o f p r o f i l e B ( r i g h t hand s i d e ) c o n s i s t s i n f a c t o f two c l o s e l y spaced b u t d i s t i n c t s t e p s . Such " s p l i t t i n g " of t e m p e r a t u r e s t e p s can a l s o be found i n Drops 6 and 7, i n a l e s s pronounced f a s h i o n . Drop 9. Drop 9 was also made at s t a t i o n Howe 4, i n the v i c i n i t y of Drops 7 and 8 and one hour a f t e r Drop 8. The o v e r a l l p r o f i l e i s presented i n f i g . 32. Four d e t a i l e d p r o f i l e s taken from Drop 9 are presented here. F i g . 49 presents the deta i l e d p r o f i l e between 28 and 35 m, the same depth range as f i g . 44 from Drop 7. A patch of gradient variance occurs between 32.5 and 34 m, within a l o c a l temperature mini-mum. At 32.5 m, there i s a 0.2 m thick region where the temperature decreases downwards. I t i s accompanied by only a low amplitude grad-ient pulse. The most i n t e r e s t i n g aspect of f i g . 49 i s the s t r i k i n g resemblance that i t presents to f i g . 44 of Drop 7. Most temperature changes of one fig u r e can be paired with s i m i l a r ones i n the other and the absolute values of the temperatures are very close. This gives the impression that the d e t a i l s of the temperature p r o f i l e s may extend much farther than the spacing of the two probes i n a double p r o f i l e and much longer than several hours. Figures 50 and 51 come from a region of the water column where Drops 7 and 8 presented two large temperature changes separated by a minor maximum and minimum. Drop 9 presents the same " f i n e structure" but i n a d i s t o r t e d fashion. In f i g . 50, the upper side of the temperature maximum consists of a "ramp" rather than a temperature step. The bottom of the temperature maximum i s very smooth and the corresponding gradient s i g n a l has a unique aspect. Most of the grad-ient variance i s associated with the patch located on the ramp where t h e mean t e m p e r a t u r e i n c r e a s e s w i t h d e p t h . F i g u r e 51 p r e s e n t s t h e second t e m p e r a t u r e s t e p . H e r e , i t c o n s i s t s o f a m i x t u r e o f ramp and s t e p on b o t h d e t a i l e d p r o f i l e s . N o t i c e t h a t on t r a c e A, t h e t e m p e r a t u r e s t e p g i v e s r i s e t o a s i n g l e g r a d i e n t s p i k e w h i c h a c c o u n t s f o r most o f the g r a d i e n t v a r i a n c e of t h i s r e g i o n o f t h e w a t e r column. D u r i n g t h e p r o c e s s i n g o f t h e d a t a , i t was n o t c l e a r a t f i r s t whether t h i s s p i k e was r e a l o r s p u r i o u s d a t a . T r a c e B showed t h a t i t was r e a l ( a l t h o u g h t h e two t e m p e r a t u r e s t e p s a r e p r e s e n t e d s i d e by s i d e , t h e y were sensed a t s l i g h t l y d i f f e r e n t t i m e s and c o u l d n o t a r i s e from a common s o u r c e o f s p u r i o u s s i g n a l ) . F i g . 52 p r e s e n t s a d e t a i l e d p r o f i l e f r o m t h e depth range o f 65 t o 72 m. A mean g r a d i e n t o f about 0.02 C°/m e x i s t s a c r o s s t h e p r o -f i l e . I t compares t o t h e l o w e r p a r t o f f i g . 46 (Drop 7 ) . The r.m.s. g r a d i e n t i s about 0.05 C°/m. F i g . 52 shows t h e a s p e c t o f t e m p e r a t u r e m i c r o s t r u c t u r e where a s i g n i f i c a n t mean g r a d i e n t e x i s t s b u t v e r y l i t t l e g r a d i e n t v a r i a n c e i s fo u n d . N o t i c e t h e p r e s e n c e o f a s p u r i o u s d a t a p o i n t n e a r 57.5 m. I t s e f f e c t i n t h e t e m p e r a t u r e p r o f i l e i s n e g l i -g i b l e b u t i t s e f f e c t on e s t i m a t e s o f the g r a d i e n t v a r i a n c e c o u l d have been l a r g e i f i t had gone u n n o t i c e d . Drop 10 F i g u r e s 53 and 54 p r e s e n t t h e m i c r o s t r u c t u r e o f Drop 10 ( s t a t i o n Howe 4.7 i n t h e I n n e r B a s i n ) between 29 and 54 m. N o t i c e t h a t t h e depth s c a l e has been compressed by a f a c t o r o f two compared w i t h t h a t o f p r e v i o u s d e t a i l e d p r o f i l e s . The p r o f i l e o f f i g . 54 f o l l o w s i m m e d i a t e l y t h a t o f f i g . 53. The de p t h l e v e l o f 42 m i s th u s o c c u p i e d by a l a y e r o f maximum t e m p e r a t u r e w h i c h i s about one metre t h i c k . A t the t o p o f f i g . 53, t h e r e i s a v e r y smooth, l o g a r i t h m i c -l i k e t e m p e r a t u r e p r o f i l e about 3 m t h i c k (between 29 and 32 m). I t i s accompanied by no s i g n i f i c a n t g r a d i e n t m i c r o s t r u c t u r e e x c e p t f o r a b r o a d , low a m p l i t u d e " p u l s e " . T h i s i s a u n i q u e o c c u r r e n c e i n t h e Howe Sound m i c r o s t r u c t u r e d a t a . Between 32 and 36 m, t h e r e i s a n o t h e r l a y e r w i t h a somewhat s i m i l a r t e m p e r a t u r e p r o f i l e b u t a v e r y d i f f e r e n t m i c r o s t r u c t u r e . H e r e , a c o m p a r a t i v e l y l a r g e amount of g r a d i e n t v a r i -ance o r i g i n a t e s i n f l u c t u a t i o n s a t s c a l e s s m a l l e r t h a n 0.1 m. T h i s v a r i a n c e has a d i f f e r e n t s p a t i a l d i s t r i b u t i o n w i t h i n each p r o f i l e . Through t h e l a y e r , t h e r e i s a l s o a s i g n i f i c a n t mean g r a d i e n t and a number of m i n o r , h i g h wave number g r a d i e n t s p i k e s . Other l a y e r s i n f i g . 53 p r e s e n t l i t t l e g r a d i e n t v a r i a n c e and the f l u c t u a t i o n s t a k e m o s t l y t h e s i g n o f the l o c a l mean g r a d i e n t . I n f i g . 54, o t h e r l a y e r s 1 t o 3 m t h i c k a r e a l s o f o u n d . Two of them ( a t 45 and 51 m) a r e f a i r l y i s o t h e r m a l w h i l e t h e o t h e r s p r e -s e n t a mean g r a d i e n t . The g r a d i e n t s i g n a l c o n s i s t s m o s t l y o f s p i k e s w h i c h have t h e s i g n o f t h e mean g r a d i e n t . Near 49 m, a l a r g e g r a d i e n t s p i k e i s c o n s i d e r e d t o be t h e r e s u l t o f a s p u r i o u s d a t a p o i n t . The m i c r o s t r u c t u r e o f t h e I n t e r m e d i a t e Water o f Drop 10 th u s c o n s i s t s o f rounded t e m p e r a t u r e s t e p s (compared t o t h o s e o f Drops 7 and 8) w h i c h a r e accompanied by "one s i d e d " g r a d i e n t f l u c t u a t i o n s . Most o f t h e l a y e r s a r e n o t even a p p r o x i m a t e l y i s o t h e r m a l . D e t a i l s s m a l l e r t h a n 0.5 m i n t h e t e m p e r a t u r e p r o f i l e s a r e u s u a l l y n o t i d e n t i f i e d i n b o t h p r o f i l e s a t once. The l a y e r s t h e m s e l v e s a r e always found i n b o t h p r o f i l e s and i t i s c l e a r t h a t t h e y e x t e n d o v e r d i s t a n c e s l a r g e r t h a n about 20 m l a t e r a l l y . As was men t i o n e d i n C h a p t e r I V , STD p r o f i l e s i n d i c a t e t h a t t h i s s o r t o f s t r u c t u r e c o u l d have been found i n much of t h e I n n e r B a s i n ' s I n t e r m e d i a t e Water. However, Drop 10 i s t h e o n l y one i n w h i c h t h e probes worked b e s i d e s t h e o t h e r drops made a t s t a t i o n Howe 4 and i n t h e Outer B a s i n . Summary I n t h e I n t e r m e d i a t e Water, Drops 7, 8 and 9 p r e s e n t a s i m i -l a r f i n e and m i c r o s t r u c t u r e . C o m p a r a t i v e l y l a r g e t e m p e r a t u r e s t e p s a r e found i n a l l t h r e e p r o f i l e s between 45 and 55 m. The v e r t i c a l sequence o f t e m p e r a t u r e l a y e r s between t h e s e s t e p s i s s i m i l a r i n t h e t h r e e p r o f i l e s a l t h o u g h t h e t h i c k n e s s o f i n d i v i d u a l l a y e r s , i f t h e y a r e t h e same ones, v a r i e s by s e v e r a l m e t r e s . Drops 7, 8 and 9 a l s o have s i m i l a r v e r t i c a l t e m p e r a t u r e sequences i n t h e 15 t o 45 m range and s u g g e s t t h a t s t r u c t u r e s 1 t o 3 m t h i c k may re m a i n r e c o g n i z a b l e o v e r p e r i o d s o f a t l e a s t s e v e r a l h o u r s and o v e r d i s t a n c e s much l o n g e r t h a n t h e n o m i n a l 20 m w h i c h s e p a r a t e ' t h e two pr o b e s i n any g i v e n p r o f i l e . Most o f t h e g r a d i e n t v a r i a n c e found i n t h e I n t e r m e d i a t e Water of t h e I n n e r B a s i n i s a s s o c i a t e d w i t h t h e g r a d i e n t s p i k e s c o n -n e c t e d t o t h e l a r g e t e m p e r a t u r e s t e p s f o u n d between 45 and 55 m. Other minor p a t c h e s o f g r a d i e n t v a r i a n c e r e s u l t from s m a l l groups o f low a m p l i t u d e g r a d i e n t s p i k e s w h i c h o c c u r n e a r the minor t e m p e r a t u r e s t e p s . These patches are usually seen on both p r o f i l e s of a p a i r and seem to extend l a t e r a l l y further than the nominal 20 m probe separation. In the temperature p r o f i l e s , d e t a i l s as th i n as 0.2 m can be i d e n t i f i e d at once on both p r o f i l e s of a p a i r . The f i n e structure of Drop 10 d i f f e r s markedly from that of Drops 7, 8 and 9. I t presents numerous layers and several temperature maxima and minima. Most layers are not isothermal and the temperature steps which separate them are rounded compared to those of the preced-ing drops. Gradient variance a r i s e s mostly from "one sided" gradient f l u c t u a t i o n s , as i n the previous drops. D) Inner Basin Deep Water (February 1974). Three deta i l e d p r o f i l e s from the Deep Water are presented here. The f i r s t two, f i g . 55 and 56, show a microstructure patch found i n Drop 7 between 130 and 150 m. The other p r o f i l e shows a patch found i n Drop 8 near 105 m. The depth scale of the p r o f i l e s i s the same one which was used f o r Drop 10. Through f i g . 55 and 56, the temperature p r o f i l e s of both probes present an "S" shape. This i s also v i s i b l e i n the o v e r a l l pro-f i l e of Drop 7 with a magnified temperature scale ( f i g . 34). The d e t a i l s of each p r o f i l e of the p a i r d i f f e r s i g n i f i c a n t l y at scales smaller than 3m. For instance, i n p r o f i l e B the downwards temperature increase takes place i n a-graded fashion over 2.5 m. In p r o f i l e A, the same temperature increase takes place i n one single step where the g r a d i e n t peaks a t more t h a n 4.5 C /m. The g r a d i e n t v a r i a n c e a s s o c i -a t e d w i t h t h e s p i k e o f p r o f i l e A i s o f t h e same o r d e r o f magnitude as the v a r i a n c e a s s o c i a t e d w i t h t h e c o r r e s p o n d i n g p a t c h i n p r o f i l e B. Many o t h e r d i f f e r e n c e s a r e a l s o found i n the t h i c k n e s s o f f e a t u r e s t h a t can be i d e n t i f i e d on b o t h p r o f i l e s . F i g . 57 shows a m i c r o s t r u c t u r e p a t c h w h i c h i s found between 100 and 110 m i n Drop 8, w i t h i n a s l i g h t t e m p e r a t u r e minimum ( s e e t h e o v e r a l l p r o f i l e w i t h a m a g n i f i e d t e m p e r a t u r e s c a l e o f f i g . 3 5 ) . The te m p e r a t u r e d i f f e r e n c e s f o u n d h e r e a r e s m a l l compared t o what has been found i n o t h e r d r o p s (about 0.01 C° h e r e ) . The g r a d i e n t a l s o peaks a t c o m p a r a t i v e l y l ow v a l u e s ( t y p i c a l l y 1 C°/m). Much of t h e g r a d i e n t v a r i a n c e i s a s s o c i a t e d w i t h s c a l e s s m a l l e r t h a n 0.05 m and t h e g r a d i e n t peak v a l u e s a r e d i s t r i b u t e d about e q u a l l y between p o s i t i v e and n e g a t i v e v a l u e s . E x c e p t f o r a few p a t c h e s , t h e Deep Water o f Howe Sound p r e s e n t s v e r y l i t t l e g r a d i e n t v a r i a n c e . When t e m p e r a t u r e d i f f e r e n c e s a r e p r e s e n t , t he two pr o b e s g i v e p r o f i l e s t h a t d i f f e r s i g n i f i c a n t l y a t s c a l e s l o w e r t h a n 2 or 3m. I t i s i n t e r e s t i n g t o n o t i c e t h a t between 80 and 110 m, t h e w a t e r columns o f Drops 7 t o 10 have s i m i l a r tempera-t u r e p r o f i l e s b u t t h a t o n l y Drop 8 p r e s e n t s a l a r g e p a t c h o f g r a d i e n t v a r i a n c e . V.3 D i s c u s s i o n . a) Summary of m i c r o s t r u c t u r e d e s c r i p t i o n : I n t h e p r e c e d i n g s e c t i o n , s e v e r a l e x p r e s s i o n s have been used r e p e a t e d l y f o r d e s c r i b i n g f e a t u r e s o f t h e t e m p e r a t u r e f i n e and m i c r o s t r u c t u r e . Here, a l i s t i s p r e s e n t e d . As seen from s c a l e s o f 1 t o 5 m , segments o f t h e t e m p e r a t u r e p r o f i l e s were d e s c r i b e d i n terms o f the mean t e m p e r a t u r e g r a d i e n t a c r o s s them. Here, "mean" o r " l o c a l mean" i n d i c a t e s t h a t a v e r a g i n g i s made o v e r t h a t segment. Thus t h e l o c a l mean g r a d i e n t may be a s s o c i a t e d w i t h a temporary f e a t u r e o f t h e w a t e r column o r may have a s i g n d i f f e -r e n t from t h a t o f the " o v e r a l l mean g r a d i e n t " a v e r a g e d o v e r a l a r g e p o r t i o n o f the w a t e r column. •As seen from s c a l e s of 0.5 t o 2 m , t e m p e r a t u r e m i c r o s t r u c t u r e can be d e s c r i b e d r o u g h l y i n terms o f : "Temperature s t e p s " when a t e m p e r a t u r e change t a k e s p l a c e o v e r a v e r t i c a l d i s t a n c e s m a l l e r t h a n 0.5 m ( i . e . i n f i g . 45 and 5 4 ) . "Temperature ramps" when a t e m p e r a t u r e change t a k e s p l a c e o v e r a v e r t i -c a l d i s t a n c e o f 1 m o r more i n a g r a d u a l f a s h i o n ( i . e . f i g . 4 1 ) . " i r r e g u l a r t e m p e r a t u r e change" when a t e m p e r a t u r e change t a k i n g p l a c e o v e r v e r t i c a l d i s t a n c e s l a r g e r t h a n 1 m i s accompanied by l a r g e t e m p e r a t u r e f l u c t u a t i o n s a t s m a l l e r s c a l e s ( i . e . f i g . 2 2 ) . Much o f t h e t e m p e r a t u r e g r a d i e n t m i c r o s t r u c t u r e can be d e s c r i b e d i n terms o f : - S p i k e s and p u l s e s as a r e seen, f o r i n s t a n c e , i n f i g . 41. -"one s i d e d g r a d i e n t s i g n a l " when m i c r o s t r u c t u r e c o n s i s t s o f a p a t c h o f g r a d i e n t f l u c t u a t i o n s w h i c h peak m o s t l y w i t h one s i g n a s , f o r i n s t a n c e , i n f i g . 24. - " s y m m e t r i c a l g r a d i e n t f l u c t u a t i o n s " when the g r a d i e n t f l u c t u a t i o n s p r e s e n t peaks t a k i n g b o t h s i g n s w i t h about e q u a l f r e q u e n c y a s , f o r i n s t a n c e , i n f i g . 21. V.3.b) R e l a t i o n s h i p s between t e m p e r a t u r e and t e m p e r a t u r e g r a d i e n t m i c r o s t r u c t u r e : The g r a d i e n t s i g n a l d i s p l a y e d i n the f i g u r e s i s s i m p l y t h e d e r i v a t i v e o f t h e t e m p e r a t u r e s i g n a l . Beyond t h i s r e l a t i o n s h i p , o t h e r q u e s t i o n s may be a s k e d such as: what t y p e o f g r a d i e n t m i c r o s t r u c t u r e i s f o und t o accompany such and such a ty p e o f t e m p e r a t u r e m i c r o -s t r u c t u r e o r f i n e s t r u c t u r e ? G a r g e t t (1976) has a l s o sought suc h r e l a t i o n s h i p s and some o f h e r c o n c l u s i o n s a r e me n t i o n e d below. Here a r e some o b s e r v a t i o n s w h i c h came fr o m e x a m i n i n g t h i s d a t a s e t . When t h e l o c a l mean g r a d i e n t i s n e g a t i v e ( t e m p e r a t u r e d e c r e a -s i n g u p w a r d s ) , t e m p e r a t u r e s t e p s and g r a d i e n t s p i k e s a r e o f t e n f o u n d (see f i g . 48, 50, 5 1 ) . When t h e l o c a l mean g r a d i e n t i s p o s i t i v e , t h e r e i s o f t e n l i t t l e g r a d i e n t v a r i a n c e compared w i t h t h a t f o u n d i n n e i g h b o u r i n g r e g i o n s o f t h e w a t e r column. The p r o f i l e s l o o k smoother (see f i g . 50 near 46 m). "Symmetric" p a t c h e s of s m a l l s c a l e g r a d i e n t f l u c t u a t i o n show no c l e a r p r e f e r e n c e w i t h r e s p e c t t o the s i g n o f t h e t e m p e r a t u r e g r a d i e n t (see f o r i n s t a n c e f i g . 21 and 2 3 ) . There a r e i n s t a n c e s where t h i s t y p e of p a t c h i s f ound j u s t above o r u n d e r n e a t h a t e m p e r a t u r e change ( f i g . 21, 41, 45) w h i l e i n o t h e r c a s e s , t h e p a t c h c o n s t i t u t e s t h e t e m p e r a t u r e change t h r o u g h an " i r r e g u l a r " t y p e of t e m p e r a t u r e p r o -f i l e ( f i g . 42, 43, 5 6 ) . Temperature s t e p s a r e o f t e n a s s o c i a t e d w i t h s i n g l e g r a d i e n t s p i k e s o r a s m a l l group o f them. However, i t i s o b s e r v e d t h a t t h e t e m p e r a t u r e g r a d i e n t v a r i a n c e a s s o c i a t e d w i t h t e m p e r a t u r e s t e p s cannot be p r e d i c t e d on t h e b a s i s of t h e t e m p e r a t u r e d i f f e r e n c e a l o n e . There a r e i n s t a n c e s of w i d e , low a m p l i t u d e g r a d i e n t p u l s e s as w e l l as o f s p i k e s t h i n n e r t h a n what the p r o b e s can r e s o l v e and w i t h a m p l i t u d e s h i g h e r t h a n c o u l d be r e c o r d e d by t h e p r o b e s (see f i g . 45 and 5 1 ) . F o r a g i v e n t e m p e r a t u r e change, t h e t h i n n e r i s t h e g r a d i e n t p u l s e , the l a r g e r a r e i t s a m p l i t u d e and a s s o c i a t e d v a r i a n c e . The o b s e r v a t i o n s thus i n d i c a t e t h a t t h e s i z e o f a t e m p e r a t u r e change does n o t d e t e r m i n e the w i d t h o f t h e g r a d i e n t p u l s e s t h a t a r e a s s o c i a t e d w i t h i t . V.3.c) L a t e r a l e x t e n t of m i c r o s t r u c t u r e i n Howe Sound. - G i v e n two t e m p e r a t u r e p r o f i l e s o b t a i n e d s i m u l t a n e o u s l y by two p robes s e p a r a t e d by something l i k e 10 o r 20 m, what i s t h e s i z e of the s m a l l e s t s t r u c t u r e s w h i c h can be i d e n t i f i e d on b o t h p r o f i l e s a t once? T h i s d i s c u s s i o n b e a r s on t h e F e b r u a r y 1974 d a t a s i n c e o n l y t h e n were d o u b l e p r o f i l e s made. See c h a p t e r I I I f o r d i s c u s s i o n of t h e p r o b e s ' l a t e r a l s e p a r a t i o n . I n t h e upper 100 m o f the I n n e r B a s i n ( F e b r u a r y 1 974), d e t a i l e d p r o f i l e s ( f i g . 44 t o 54) show t h a t t h e p r o f i l e s d i f f e r m o s t l y a t s c a l e s s m a l l e r t h a n 0.1 t o 0.3 m. I n o t h e r words, m i n o r tempera-t u r e maxima o r minima t h i c k e r t h a n 0.1 t o 0.3 m can be i d e n t i f i e d on b o t h p r o f i l e s of p a i r s w i t h enough c o n s i s t e n c y t o c o n v i n c e one t h a t t h e y a r e p a r t of t h e same w a t e r " l e n s e s " o r l a y e r s . F e a t u r e s t h i n n e r t h a n 0.1 m d e f i n i t e l y d i f f e r i n p a i r s o f p r o f i l e s . A n o t h e r way t o l o o k a t t h i s i s t o s t a t e t h a t (by v i s u a l e x a m i n a t i o n ) i f t h e s e p r o f -i l e s were low - p a s s e d f i l t e r e d w i t h a c u t - o f f a t 0.3 m, p r o f i l e s o f a p a i r would l o o k a l m o s t i d e n t i c a l . Note however t h a t c r o s s - s p e c t r a l a n a l y s i s m i ght n o t agree w i t h t h i s r e s u l t because i d e n t i f i a b l e f e a -t u r e s o f t e n have d i f f e r e n t t h i c k n e s s o r s l i g h t l y d i f f e r e n t r e l a t i v e p o s i t i o n i n the w a t e r column; t h e r e l a t i v e d i s p l a c e m e n t s c o u l d be a l i m i t i n g f a c t o r i n e s t i m a t i n g s p e c t r a l c o h e r e n c e s . Near 50 m, Drops 7, 8 and 9 p r e s e n t t e m p e r a t u r e s t e p s where s i m i l a r i t y seems t o s t o p a t s c a l e s s m a l l e r t h a n 0.5 m. I n t h e Deep Water o f t h e I n n e r B a s i n , few m i c r o s t r u c t u r e f e a t u r e s a r e a v a i l a b l e f o r m a t c h i n g . F i g . 55 t o 57 show t h a t s c a l e s s m a l l e r t h a n 1 t o 3 m a r e u s u a l l y d i f f e r e n t i n two p r o f i l e s o f a p a i r . Throughout t h e Outer B a s i n ' s Drop 6, s i m i l a r i t y between t h e p r o f i l e s i s s m a l l a t s c a l e s s m a l l e r t h a n 1 o r 2 m i n most c a s e s ( f i g . 41 t o 4 3 ) . - G i v e n a t e m p e r a t u r e change w h i c h i s sampled by two n e i g h -b o u r i n g p r o b e s , i s the same tijpz. of m i c r o s t r u c t u r e o b s e r v e d by both? Throughout t h e Howe Sound o b s e r v a t i o n s , when one t e m p e r a t u r e p r o f i l e was s t e p p y , the o t h e r one u s u a l l y was a l s o . When one p r o f i l e p r e s e n t e d h i g h a m p l i t u d e g r a d i e n t s p i k e s , so d i d the o t h e r one. T h i s a p p l i e s a l s o f o r t e m p e r a t u r e "ramps". However, when a p a t c h o f " s y m m e t r i c a l g r a d i e n t f l u c t u a t i o n s " w i t h g r a d i e n t v a r i a n c e concen-t r a t e d a t s c a l e s s m a l l e r t h a n 0.05 m was found i n one p r o f i l e , t h e o t h e r p r o f i l e seldom p r e s e n t e d a p a t c h w i t h s i m i l a r e x t e n t . Many examples o f t h i s were f o u n d i n Drop 6 ( f i g . 41 t o 4 3 ) . I n Drop 8 ( f i g . 5 7 ) , a 10 m t h i c k p a t c h o f g r a d i e n t v a r i a n c e i s found by b o t h p r o b e s b u t t h e g r a d i e n t v a r i a n c e i s d i s t r i b u t e d d i f f e r e n t l y w i t h i n each p r o f i l e . These o b s e r v a t i o n s i n d i c a t e t h a t p a t c h e s o f t e m p e r a t u r e m i c r o s t r u c t u r e o f t h e " s y m m e t r i c a l " , s m a l l s c a l e t y p e do n o t e x t e n d l a t e r a l l y o v e r d i s t a n c e s as l a r g e as 20 m i n t h e Ou t e r B a s i n (and s e l -dom o c c u r i n the I n n e r B a s i n i n F e b r u a r y 1974). O t h e r i d e n t i f i e d t y p e s o f m i c r o s t r u c t u r e appear t o e x t e n d l a t e r a l l y o v e r d i s t a n c e s l a r g e r t h a n t h e 20 or so metre s w h i c h s e p a r a t e d the f r e e - f a l l i n g p r o b e s . V.3.d) T u r b u l e n t o r no t ? There a r e p a t c h e s o f t e m p e r a t u r e m i c r o s t r u c t u r e w h i c h , i n t u i -t i v e l y , have seemed t o be " t u r b u l e n t " t o p e o p l e who have s t u d i e d t h e d e t a i l e d p r o f i l e s . The one metre t h i c k p a t c h f ound i n Drop 6 ( f i g . 41) a t 58 m i s one example o f t h i s . There a r e a l s o o t h e r r e g i o n s o f t h e w a t e r column w h i c h , i n t u i t i v e l y s t i l l , seem n o t t o be t u r b u l e n t . The l o w e r s i d e o f a t e m p e r a t u r e maximum found i n Drop 9 ( f i g . 52) i s one such example. Y e t , between extreme c a s e s l i e s t he m a j o r i t y o f m i c r o -s t r u c t u r e f e a t u r e s . I s such an assessment v a l i d o r s h o u l d " i n t u i t i o n " be c o n s i d e r e d m i s l e a d i n g ? Can t e m p e r a t u r e m i c r o s t r u c t u r e a l o n e a l l o w one t o a s s e s s t h e t u r b u l e n t o r n o n - t u r b u l e n t n a t u r e o f a f l o w ? F o r t h e purpose o f t h i s d i s c u s s i o n , the meaning of t u r b u l e n c e i s r e s t r i c t e d t o random, s m a l l s c a l e , q u a s i - i s o t r o p i c v e l o c i t y f l u c t u -a t i o n s . When t h i s o c c u r s , v e r t i c a l exchanges o f f l u i d must t a k e p l a c e and the l o c a l d e n s i t y s t r a t i f i c a t i o n must be " t u r n e d o v e r " a t s m a l l s c a l e s a t l e a s t . One t h e n e x p e c t s an i n s t a n t a n e o u s p r o f i l e o f temper-a t u r e t o p r e s e n t a d i s o r d e r e d a s p e c t a t s m a l l s c a l e s and an i n s t a n t a n -eous p r o f i l e o f t h e v e r t i c a l g r a d i e n t s h o u l d p r e s e n t f l u c t u a t i o n s w h i c h show l i t t l e p r e f e r e n c e f o r one s i g n o r t h e o t h e r . T h u s , m i c r o -s t r u c t u r e d e s c r i b e d e a r l i e r as " i r r e g u l a r g r a d i e n t " and s m a l l s c a l e " s y m m e t r i c a l " g r a d i e n t f l u c t u a t i o n s a r e t h e most c o n s i s t e n t w i t h t u r b u l e n t s t i r r i n g . I r r e g u l a r t e m p e r a t u r e p r o f i l e s and " s y m m e t r i c a l " s m a l l s c a l e g r a d i e n t f l u c t u a t i o n s do n o t n e c e s s a r i l y mean t h a t t h e f l u i d w h i c h i s b e i n g sampled i s i n t u r b u l e n t m o t i o n . One can t h i n k o f c o u n t e r examples. Take t h e case o f a b r i e f t u r b u l e n t e p i s o d e i n v o l -v i n g w a t e r s t r a t i f i e d i n d e n s i t y and t e m p e r a t u r e . Once t h r e e -d i m e n s i o n a l t u r b u l e n c e s u b s i d e s , t h e p a r t i a l l y m ixed volume of w a t e r r e o r g a n i z e s i t s e l f a c c o r d i n g t o i t s new d e n s i t y s t r u c t u r e . Because h e a t and s a l t have d i f f u s e d a t d i f f e r e n t m o l e c u l a r r a t e s , t h e r e s u l t -i n g s t a b l e w a t e r column w i l l p r e s e n t an " i r r e g u l a r " t e m p e r a t u r e p r o f i l e w i t h s m a l l s c a l e t e m p e r a t u r e i n v e r s i o n s and g r a d i e n t f l u c t u a -t i o n s o f b o t h s i g n s . Y e t , i t i s no more t u r b u l e n t i n the s e m i -i s o t r o p i c s e n s e . M o l e c u l a r h e a t d i f f u s i o n a c t s towards d i s s i p a t i n g s m a l l s c a l e t e m p e r a t u r e g r a d i e n t v a r i a n c e . . The p r e s e n c e o f h i g h wave number g r a d i e n t v a r i a n c e i n m i c r o s t r u c t u r e i s t h u s t a k e n t o s u g g e s t t h a t r e c e n t " a c t i v i t y " has t a k e n p l a c e o r i s g o i n g on. E c k a r t (1948) has shown t h a t t e m p e r a t u r e g r a d i e n t v a r i a n c e r e s u l t s from t h e d e f o r m a t i o n o f t h e t e m p e r a t u r e f i e l d by t h e r a t e o f s t r a i n o f t h e f l u i d ' s m o t i o n . Due t o t h e r m a l d i f f u s i v i t y , an i n f i n i t e l y s h a r p t e m p e r a t u r e s t e p would t a k e 180 sec t o t h i c k e n t o 0.01 m i n w a t e r (Osborn and Cox, 1972). D i m e n s i o n a l c o n s i d e r a t i o n s i n v o l v i n g a c o n s t a n t r a t e o f s t r a i n and t h e t h e r m a l d i f f u s i v i t y o f w a t e r i n d i c a t e t h a t , i n an inhomogene-ous t e m p e r a t u r e f i e l d , t e m p e r a t u r e g r a d i e n t v a r i a n c e a t s c a l e s o f t h e o r d e r o f 0.01 m can be s u s t a i n e d by a r a t e o f s t r a i n o f (180 sec) ^ o r 0.005 (m sec "S m Thus, c o m p a r a t i v e l y weak s h e a r s a r e s u f f i c i e n t t o cause g r a d i e n t v a r i a n c e a t s c a l e s s m a l l e r t h a n t h o s e r e s o l v e d by t h e i n s t r u m e n t s , w i t h o u t r e c o u r s e t o t u r b u l e n t p r o c e s s e s . Osborn ( p e r s o n a l communication) has made o b s e r v a t i o n s o f b o t h t e m p e r a t u r e and v e l o c i t y m i c r o s t r u c t u r e . He has found t h a t p a t c h e s o f b o t h u s u a l l y o c c u r t o g e t h e r . I n s e v e r a l i n s t a n c e s , he has o b s e r v e d m i c r o s t r u c t u r e s h e a r v a r i a n c e where no o r l i t t l e t e m p e r a t u r e g r a d i e n t v a r i a n c e was f o u n d . T h i s o c c u r s where t e m p e r a t u r e i s homo-geneous and b r i n g s up one more p o i n t : p a t c h e s o f v e l o c i t y m i c r o -s t r u c t u r e (and e v e n t u a l l y t u r b u l e n t m o t i o n ) may go u n d e t e c t e d by t e m p e r a t u r e s e n s o r s when the t e m p e r a t u r e d i s t r i b u t i o n i s homogeneous. On the b a s i s of t h e p r e c e d i n g d i s c u s s i o n , a t t e m p t i n g t o a s s e s s t h e o c c u r r e n c e of t u r b u l e n c e w i t h t e m p e r a t u r e s e n s o r s i s r i s k y , a t b e s t . T u r b u l e n c e may go u n n o t i c e d o r e l s e m i c r o s t r u c t u r e p a t c h e s may be n o n - t u r b u l e n t ( i n t h e s e m i - i s o t r o p i c s e n s e ) . F e a t u r e s w h i c h a r e most c o n s i s t e n t w i t h t u r b u l e n c e a r e t h o s e w h i c h p r e s e n t " s y m m e t r i c a l " g r a d i e n t f l u c t u a t i o n s a t s m a l l s c a l e s w i t h a t e m p e r a t u r e p r o f i l e s u g g e s t i n g a l o c a l d e n s i t y o v e r t u r n . Such f e a t u r e s a r e f o u n d , f o r i n s t a n c e , i n f i g . 41 t o 43 and 57. They a r e c a l l e d h e r e " t u r b u l e n t - l i k e " . On t h e b a s i s of t h e p r e c e d i n g d i s c u s s i o n , t h e r e a r e a l s o f e a t u r e s w h i c h a r e c l e a r l y n o n - t u r b u l e n t . T h i s i s t h e c a s e of r e g i o n s of the w a t e r column w h i c h p r e s e n t a monotonous t e m p e r a t u r e p r o f i l e such as f i g . 52 (Drop 8 n e a r 60 m). I n t e m p e r a t u r e "ramps" such as t h o s e found i n f i g . 24 and f i g . 41 ( n e a r 59 m), t h e r e a r e v e r y s m a l l i n v e r s i o n s i n t h e mean t r e n d . ' I n v i e w o f t h e r e g u l a r s t r u c t u r e p r e -s e n t e d by t h e p r o f i l e s , t u r b u l e n t s t i r r i n g seems t o be an u n l i k e l y e x p l a n a t i o n ' ( a t l e a s t a t the t i m e when t h a t f e a t u r e was s a m p l e d ) . I n Drop 6 ( O u t e r B a s i n , 1 9 7 4 ) , most o f t h e g r a d i e n t v a r i a n c e i s a s s o c i a t e d w i t h a t u r b u l e n t - l i k e m i c r o s t r u c t u r e . The p a t c h e s have t h i c k n e s s e s o f one h a l f t o two m e t r e s and, as shown i n the p r e c e d i n g s u b - s e c t i o n , t h e y seem t o e x t e n d l a t e r a l l y f o r l e s s t h a n about 20 m. I n t h e I n t e r m e d i a t e Water of t h e I n n e r B a s i n (10 t o 100 m) most o f t h e g r a d i e n t v a r i a n c e i s a s s o c i a t e d w i t h m i c r o s t r u c t u r e f e a t u r e s w h i c h a r e n o t t u r b u l e n t - l i k e . They c o n s i s t of t e m p e r a t u r e s t e p s accom-p a n i e d by c l u s t e r s of "one s i d e d " g r a d i e n t m i c r o s t r u c t u r e and t h e s e v a r i a n c e p a t c h e s seem t o e x t e n d l a t e r a l l y f o r more t h a n about 20 m. I n t h e Deep Water of t h e I n n e r B a s i n , some f e a t u r e s a r e t u r b u l e n t -l i k e and o t h e r s a r e n o t b u t due t o t h e p a u c i t y of d a t a from t h i s r e g i o n , no c o n c l u s i o n can be drawn. I n t h e November 1973 p r o f i l e s (see f i g . 21 t o 2 4 ) , o c c u r r e n c e s of a l l t y p e s a r e f o u n d . The numer-ous t e m p e r a t u r e i n v e r s i o n s w h i c h a r e f ound o c c u r a t s c a l e s of i m o r l a r g e r and seem t o r e s u l t more from a d v e c t i v e p r o c e s s e s such as " i n t e r l e a v i n g " r a t h e r t h a n f r o m t u r b u l e n t o v e r t u r n . V.3.e) D o u b l y - d i f f u s i v e o r n o t ? D o u b l y - d i f f u s i v e c o n v e c t i o n has f a s c i n a t e d o c e a n o g r a p h e r s e v e r s i n c e the i d e a of i t was o u t l i n e d and t r i e d i n l a b o r a t o r y t a n k s . When the t e m p e r a t u r e and s a l i n i t y g r a d i e n t s p r o v i d e o p p o s i t e c o n t r i -b u t i o n s t o t h e d e n s i t y g r a d i e n t of a s t a b l e w a t e r column, t h e r e i s a p o s s i b i l i t y t h a t l o c a l d e n s i t y i n s t a b i l i t i e s d e v e l o p and grow because of t h e l a r g e d i f f e r e n c e between t h e m o l e c u l a r d i f f u s i o n r a t e s o f h e a t and s a l t . The r e a d e r i s r e f e r r e d t o T u r n e r (1973) f o r a d e t a i l e d d i s -c u s s i o n o f work c a r r i e d on t h i s t o p i c b e f o r e 1973 and t o Monin e t a l . (1974) f o r an o v e r v i e w o f work c a r r i e d on b e f o r e 1972. P r e s u m p t i o n o f d o u b l y - d i f f u s i v e c o n v e c t i o n i n t h e ocean i s u s u a l l y based on v e r t i c a l p r o f i l e s o f t e m p e r a t u r e and s a l i n i t y w h i c h p r e s e n t r e g u l a r l y spaced l a y e r s o f homogeneous p r o p e r t i e s s e p a r a t e d by sharp p r o p e r t y changes o f t e n c a l l e d i n t e r f a c e s , i n w a t e r columns where, t o b e g i n w i t h , the p r o p e r t y g r a d i e n t s p r e s e n t v a l u e s c o n s i s t e n t w i t h d o u b l y - d i f f u s i v e c o n v e c t i o n . I n the d a t a p r e s e n t e d h e r e , o n l y the t e m p e r a t u r e g r a d i e n t i s known w i t h some p r e c i s i o n . Over most of t h e w a t e r column, t e m p e r a t u r e i n c r e a s e s w i t h d e p t h . S i n c e t h e w a t e r column i s s t a b l e , s a l i n i t y must i n c r e a s e w i t h d e p t h a t l e a s t i n a compensating f a s h i o n . The o v e r a l l p r o p e r t y g r a d i e n t s a r e t h e n c o n s i s t e n t w i t h t h e development of a d o u b l y - d i f f u s i v e i n s t a b i l i t y o f t h e " d i f f u s i v e t y p e " ( s e e T u r n e r , 1973). However, t h e l a r g e and r e g u l a r s t e p s w h i c h have been o b s e r v e d e l s e w h e r e a r e n o t found i n t h e Howe Sound p r o f i l e s . What i s f o u n d i s t h a t d i f f e -r e n t t y p e s o f t e m p e r a t u r e m i c r o s t r u c t u r e t e n d t o be a s s o c i a t e d w i t h p o s i t i v e and n e g a t i v e v e r t i c a l t e m p e r a t u r e g r a d i e n t s . M o r e o v e r , t h e g r a d i e n t v a r i a n c e a s s o c i a t e d w i t h n e g a t i v e t e m p e r a t u r e g r a d i e n t s i s l a r g e r t h a n t h a t a s s o c i a t e d w i t h p o s i t i v e t e m p e r a t u r e g r a d i e n t s . G a r g e t t (1976) a l s o o b s e r v e d t h i s r e l a t i o n s h i p between the i n t e n s i t y o f g r a d i e n t v a r i a n c e and t h e f i n e s t r u c t u r e g r a d i e n t w h i l e Gregg and Cox (1972) a l s o o b s e r v e d t h e s t e p p y c h a r a c t e r o f m i c r o s t r u c t u r e when t e m p e r a t u r e l o c a l l y i n c r e a s e s downwards. These a u t h o r s a g r e e t h a t d o u b l y - d i f f u s i v e c o n v e c t i o n i s v e r y l i k e l y t o p l a y a r o l e i n s h a p i n g m i c r o s t r u c t u r e . Gregg and Cox (1972) d i s c u s s t h i s i n more d e t a i l and show t h a t S o r e t d i f f u s i o n c o u l d a l s o be r e l e v a n t . However, on t h e b a s i s o f t h e i r d a t a and on t h e s t a t e o f knowledge, t h e s e a u t h o r s c o u l d n o t come t o a c o n c l u s i o n about t h e i m p o r t a n c e o f d o u b l y -d i f f u s i v e p r o c e s s e s i n o c e a n i c e n v i r o n m e n t s . The same a p p l i e s h e r e . C h a p t e r V I C o n c l u s i o n Howe Sound's w a t e r i s shown t o p r e s e n t t h r e e w a t e r masses. The S u r f a c e L a y e r o c c u p i e s t h e upper 10 m and e v o l v e s under t h e i n f l u e n c e o f f r e s h w a t e r r u n o f f , t i d e s and m e t e o r o l o g i c a l e f f e c t s . The I n t e r m e d i a t e Water i s c h a r a c t e r i z e d by i t s exchanges w i t h t h e S t r a i t o f G e o r g i a . F l u s h i n g t i m e can be as s h o r t as a few weeks. The I n t e r m e d i a t e Water i s c o n s i d e r e d t o occupy t h e whole o f t h e Ou t e r B a s i n (below 10 m) and the d e p t h range o f 10 t o 100 m i n t h e I n n e r B a s i n . The Deep Water o c c u p i e s t h e I n n e r B a s i n o n l y , below 100 m. I t s t a y s t r a p p e d f o r p e r i o d s o f months t o y e a r s . Two t e m p e r a t u r e m i c r o s t r u c t u r e c r u i s e s w h i c h were made i n Howe Sound r e v e a l e d t y p e s o f m i c r o s t r u c t u r e w h i c h v a r i e d w i t h l o c a t i o n , d e pth and t e m p e r a t u r e f i n e s t r u c t u r e . I n t h e Ou t e r B a s i n , most of the v e r t i c a l t e m p e r a t u r e g r a d i e n t v a r i a n c e 9^ o c c u r s i n a s s o c i a t i o n w i t h t u r b u l e n t - l i k e m i c r o s t r u c t u r e p a t c h e s 0.5 t o 3 m t h i c k w h i c h seem t o e x t e n d l a t e r a l l y f o r l e s s t h a n 20 m. I n t h e I n n e r B a s i n , most of the g r a d i e n t v a r i a n c e i s a s s o c i a t e d w i t h m i c r o s t r u c t u r e f e a t u r e s w h i c h appear t o be n o n - t u r b u l e n t a t t h e ti m e o f s a m p l i n g . I n t h e I n n e r B a s i n ' s I n t e r m e d i a t e Water, t h e l a t e r a l e x t e n t o f t h e g r a d i e n t v a r i a n c e p a t c h e s as w e l l as t h a t o f i n d i v i d u a l f e a t u r e s as t h i n as 0.2 m, seems t o be l a r g e r t h a n 20 m l a t e r a l l y . I n t h e Deep Water, few m i c r o s t r u c t u r e f e a t u r e s a r e d e t e c t e d . When t h e y a r e , o n l y s c a l e s l a r g e r t h a n 1 o r 2 m seem t o e x t e n d f o r more t h a n about 20 m l a t e r a l l y . R e g i o n s o f the w a t e r column where t h e t e m p e r a t u r e g r a d i e n t ( a t s c a l e s o f 0.5 t o 2m) i s p o s i t i v e ( t e m p e r a t u r e d e c r e a s i n g downwards) p r e s e n t l e s s g r a d i e n t v a r i a n c e and smoother t e m p e r a t u r e p r o f i l e s . R e g i o n s where t h e t e m p e r a t u r e g r a d i e n t i s n e g a t i v e o f t e n p r e s e n t s t e p p y t e m p e r a t u r e p r o f i l e s and t h e g r a d i e n t peaks a t c o m p a r a t i v e l y h i g h v a l u e s . These comments a p p l y t o m i c r o s t r u c t u r e w h i c h was n o t t u r b u l e n t - l i k e . I n the November 1973 d a t a , m i c r o s t r u c t u r e p a t c h e s w h i c h c o u l d be d e s c r i b e d as t u r b u l e n t - l i k e o c c u r e q u a l l y w e l l w i t h i n r e g i o n s o f mean g r a d i e n t o f b o t h s i g n s . The r o l e o f t e m p e r a t u r e m i c r o s t r u c t u r e i s examined i n t h e l i g h t o f t h e Osborn-Cox model and of a n o t h e r model f o r m i x i n g w h i c h i s d e v e l o p e d i n t h i s t h e s i s . The Oxborn-Cox model i s a p p l i e d t o t h e l o w e r p a r t o f t h e I n n e r B a s i n ' s I n t e r m e d i a t e Water. I t s u g g e s t s t h a t v e r t i c a l t u r b u l e n t d i f f u s i o n p l a y s o n l y a m i n o r r o l e i n t h e I n t e r m e d i a t e Water near 75 m, compared t o l a t e r a l a d v e c t i v e exchanges between t h e I n n e r B a s i n and t h e o u t s i d e . The m i x i n g model d e v e l o p e d h e r e r e t a i n s as i m p o r t a n t p a r a m e t e r s the t e m p e r a t u r e v a r i a n c e w i t h i n t h e Deep Water, th e mean s q u a r e t e m p e r a t u r e g r a d i e n t , m o l e c u l a r h e a t d i f f u s i o n and a ti m e s c a l e f o r t h e m i x i n g o f t h e Deep Water. B o t t l e c a s t d a t a s u g g e s t a t h r e e month ti m e s c a l e f o r m i x i n g t h e Deep Water. Deep Water g r a d i e n t v a r i a n c e d a t a a r e s c a n t b u t th e y a r e of an o r d e r o f magnitude w h i c h i s c o m p a t i b l e w i t h t h a t p r e d i c t e d by t h e model f o r t h e t h r e e month t i m e s c a l e . The r e s u l t s s u g g e s t e d by t h e models a r e l i m i t e d by t h e a b i l i t y o f t h e pr o b e s t o r e s o l v e t h e f u l l s p e c t r u m o f t e m p e r a t u r e g r a d i e n t v a r i -ance and by t h e p o s s i b l e i n t e r m i t t e n c y o f m i c r o s t r u c t u r e p r o d u c i n g e v e n t s . R e f e r e n c e s BELL, W i l l i a m H. 1973. The Exchange o f Deep Water i n Howe Sound B a s i n . P a c i f i c M a r i n e S c i e n c e D i r e c t o r a t e R e p o r t 73-13, E n v i r o n m e n t Canada, V i c t o r i a , B.C. BELL, W i l l i a m H. 1975. The Howe Sound C u r r e n t M e t e r i n g Program, Volume I I I , P a r t I - D a t a R e p o r t , S t a t i o n HS-5. P a c i f i c M a r i n e S c i e n c e R e p o r t 75-7. I n s t i t u t e o f Ocean S c i e n c e , P a t r i c i a Bay, V i c t o r i a , B.C. BUCKLEY, J o s e p h R. 1977. C u r r e n t s , w i n d s and t i d e s i n Howe Sound. Ph.D. T h e s i s , U n i v e r s i t y o f B r i t i s h C o l u m b i a , V a n c o u v e r , B.C. pp. 228. Can a d i a n H y d r o g r a p h i c S e r v i c e . 1977. Ca n a d i a n T i d e and C u r r e n t T a b l e s , V o l . 5, J u a n de Fuca and S t r a i t o f G e o r g i a . C a n a d i a n H y d r o g r a p h i c S e r v i c e , M a r i n e S c i e n c e B r a n c h , Department o f t h e E n v i r o n m e n t , Ottawa, Canada. DAHL, F i n n - E . 1977. A Note on H o r i z o n t a l G r a d i e n t s i n F j o r d s . J o u r . P h y s . Oceanog. 7_(5): 753-758. DEFANT, A l b e r t . 1961. P h y s i c a l Oceanography, V o l . I I . Pergamon P r e s s . DRINKWATER, Kenneth F. 1973. The R o l e o f T i d a l M i x i n g i n R u p e r t and H o l b e r g I n l e t s . M. Sc. T h e s i s , U n i v e r s i t y o f B r i t i s h C o l u m b i a , V a n c o u v e r , B.C. pp. 58. ECKART, C a r l . 1948. An A n a l y s i s o f t h e S t i r r i n g and M i x i n g P r o c e s s e s i n I n c o m p r e s s i b l e F l u i d s . J o u r . Mar. Res. VI I , 3 : 2 6 5 - 2 7 5 . ELLIOTT, J.A. and N.S. OAKEY. 1975. H o r i z o n t a l c o h e r e n c e o f Temperature M i c r o s t r u c t u r e . J o u r . P h y s . Oceanog. 5_: 506-515. GARGETT, Ann. 1976. An I n v e s t i g a t i o n o f t h e O c c u r r e n c e o f O c e a n i c T u r b u l e n c e w i t h r e s p e c t t o F i n e s t r u c t u r e . J o u r . Phys. Oceanog. 6:139-156. GREGG, M.C. and C.S. COX.,1972. The V e r t i c a l M i c r o s t r u c t u r e o f Temperature and S a l i n i t y . Deep Sea Res. 19:355-376. GREGG, M.C, C.S. COX and P.W. HACKER. 1973. V e r t i c a l M i c r o s t r u c t u r e Measurements i n t h e C e n t r a l N o r t h P a c i f i c . J o u r . Phys. Oceanog.' _3:458-469. I n s t i t u t e o f Oceanography o f t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a . 1973. Da t a R e p o r t 34. B r i t i s h C o l u m b i a I n l e t s and P a c i f i c C r u i s e s 1972. U n i v e r s i t y o f B r i t i s h C o l u m b i a , V a n c o u v e r , B.C. I n s t i t u t e o f Oceanography of t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a . 1974. Data R e p o r t 35. B r i t i s h C o l u m b i a I n l e t C r u i s e s 1973. U n i v e r s i t y o f B r i t i s h C o l u m b i a , V a n c o u v e r , B.C. I n s t i t u t e o f Oceanography of the U n i v e r s i t y o f B r i t i s h C o l u m b i a . 1975. Da t a R e p o r t 37. B r i t i s h C o l u m b i a I n l e t C r u i s e s 1974. U n i v e r s i t y o f B r i t i s h C o l u m b i a , V a n c o u v e r , B.C. LUECK, R o l f G., Owen HERTZMAN and Thomas R. OSBORN. 1977. The S p e c t r a l Response o f T h e r m i s t o r s . Deep Sea Res. 24:951-970. MONIN, A.S. 1977. V a r i a b i l i t y o f the Oceans. John W i l e y and Sons. OSBORN, T.R. and C.S. COX. 1972. O c e a n i c F i n e S t r u c t u r e . Geophys. F l u i d Dyn. _3:321-345. OSBORN, T.R. 1977. The D e s i g n and P e r f o r m a n c e o f F r e e F a l l M i c r o s t r u c t u r e I n s t r u m e n t s a t the I n s t i t u t e o f Oceanography. U n p u b l i s h e d m a n u s c r i p t , I n s t i t u t e o f Oceanography, U n i v e r s i t y o f B r i t i s h C o l u m b i a , Vancouver, B.C. PICKARD, G.L. 1975. A n n u a l and Lo n g e r Term V a r i a t i o n s o f Deep Water P r o p -e r t i e s i n C o a s t a l Waters o f S o u t h e r n B r i t i s h C o l u m b i a . J o u r . F i s h . Res. B o a r d Canada 32:1561-1587. STOMMEL, H. and K.N. FEDOROV. 1967. S m a l l S c a l e S t r u c t u r e i n Temperature and S a l i n i t y n e a r Timor and Mindanao. T e l l u s 19(2):306-325. TURNER, J.S. 1973. Buoyancy E f f e c t s i n F l u i d s . Cambridge U n i v e r s i t y P r e s s , 367 pp. 75 Drop L o c a t i o n Date Hour S e p a r a t i o n S e p a r a t i o n Number a t l a u n c h a t r e c o v e r y ( 1 9 7 4 ) ±10% ±50% 3 R a m i l l i e s Channel 5 Feb. 09:25 15 m 10 m 4 " " " 11:00 7 m N/A 5 " " " 13:40 3 m 20 m 6 " " " 14:10 20 m N/A 7 S t a t i o n Howe 4 6 Feb. 09:10 20 m 25 m 8 " " " 10:10 3 m 12 m 9 " " " 11:15 10 m N/A 10 S t a t i o n Howe 4.7 " 12:55 20 m 1 m 11 " " " 14:00 3 m N/A T a b l e I L i s t o f t h e d o u b l e drops made i n t h e F e b r u a r y 1974 c r u i s e i n Howe Sound's b a s i n s , t o g e t h e r w i t h t h e s e p a r a t i o n o f t h e pr o b e s a t l a u n c h and a t r e c o v e r y . 76 Drop Number Date (1973) Time L o c a t i o n Mean Square G r a d i e n t 10 3 ( C ° / m ) 2 Depth I n t e r v a l (m) P-10 P - l l P-12 P-13 P-14 P-15 P-16 21 Nov. 22 Nov. 10:25 11:20 12:30 13:30 14:10 15:20 08:43 Howe 4 Howe 3.8 Howe 4 Howe 4 Howe 4 Howe 4 Howe 4.7 11.0 18.0 46.9 18.2 22.8 39.2 17.2 38 183 27 210 28 152 27 187 19 202 28 70 28 183 T a b l e I I Times and l o c a t i o n s a t w h i c h Drops P-10 t o P-16 were made d u r i n g t h e November 1973 c r u i s e i n Howe Sound. The v a l u e s o f t h e mean s q u a r e g r a d i e n t s and t h e d e p t h i n t e r v a l s o v e r w h i c h t h e y were o b s e r v e d a r e a l s o g i v e n . The mean t e m p e r a t u r e g r a d i e n t s o v e r t h e s e i n t e r v a l s was n o t c a l c u l a t e d because t h e p r o f i l e s p r e s e n t numerous major t e m p e r a t u r e i n v e r s i o n s . 77 Drop Number I n t e r m e d i a t e Water T h i c k n e s s (m) Temperature Mean Square Change G r a d i e n t (C°) (C°/m) 2 x 10 3 6-A 6- B 7- A 7- B 8- A 8- B 9- A 9-B 10-A 10-B 152 162 80 79 89 85 82 83 83 85 2.0 1.8 1.1 1.3 1.5 1.4 1.4 1.5 1.5 1.4 35. 18. 6.2 9.8 7.1 11.4 8.3 9.0 9.0 8.1 T a b l e I I I Temperature change and g r a d i e n t v a r i a n c e f o u n d i n t h e I n t e r m e d i a t e Water i n F e b r u a r y 1974. 78 79 Figure 2 Longitudinal section of Howe Sound and cross channel sections made at the s i l l ( ) and at Howe 4 ( ). 0 1 0 0 k 2 0 0 T(°C) 7 9 S ( % o ) 2 9 31 O u t e r E a s i n T ( °C) 7 9 S ( % o ) 2 9 31 I n n e r B a s i n Figure 3 Typical winter profiles of temperature and salinity in the Outer Basin and in the Inner Basin (February 1974) CO o 81 T e m p e r a t u r e ( °C) O O) oo n o o 82 O u t e r B a s i n H o w e 2 8*3 U cL E 6 _ 3 0 . 4 o °: 3o.o >* c 29.6 oo 29.4 S A L I N I T Y 1 0 8 6 3 0 . 4 4- 30 .0 4 29 .6 29 .4 1 9 7 2 1 9 7 3 74 I n n e r B a s i n H o w e 4 . 5 30.4 + oo 29.4 J ( J A , S O . N D . J . F M A M . J . J A , S O . N . D . J j ^ 3 0 . 0 10 8 6 1 9 7 2 1973 Figure 5 Comparison between the temperature and s a l i n i t y average values in the Intermediate Water of the Inner and Outer Basin. u o a E 0) a) 2 0 0 m / \ 2 0 0 m 1 0 0 m - t - H — — I — I — I — 1 — I — t N D ' J F 1972 i i I I I N D ' J F 1 0 0 m T E M P E R A T U R E ' ' ' ' • i i i i i i I I I i i i 1 9 7 3 N D ' J F 1974 t 9 + 8 Key t o Symbols: a 250 m A 2 2 5 m __200m o 175 m O 150m • 125 m — 100m 3 0 . 0 6 f 30 .021 b) 30 .04 + N ~ , "\ o o o o o A -S-• • • / 2 0 0 m o l O O m o / \ V S A L I N I T Y H—H N D ' J F H — h - H — I — I — I — I — I — I — I -+ 3 0 . 0 6 4-30.04 4- 30 .02 1 9 7 2 N D ' J F - J — I — I — i — i — i — i — i — t -1 9 7 3 N D ' J F - I — i — i — I — i -1974 F i g u r e 6 a) and b) 84 O O O CD lO CM CM 1- euu6!S O CM —h-CM — e o o < ©C5<i0 E •090 o e <3aQ O <J8i CM 1 > CD |<D /•O o VCJ /•OO / OQ T3 > o Q c O) >} 01 -4- -4-( |/|UJ)-0'Q CD a z 0> Q Z CM u. -> Q Z CM t -T3 C 0) 3 60 •H fe SURFACE LAYER 1 | F i gure 7 L o n g i t u d i n a l s e c t i o n of Howe Sound showing what i s meant by Deep Water and Intermediate Water. CO F i g u r e 8 87 F i g u r e 9 F i g u r e 10 H* 00 C >-f ft) o E J", NOVEMBER 25 26 27 28 29 30 31 1 2 3 A 5 6 7 8 9 10 11 12 13 14 15 8 J • I0i 0 M -10J 2 0 re ft N 10 0 10_J 600 300-I 0 V iV -i r~ 11?, J2f."i29.^c§.iy_r?_§i1 J^-Q M J ° c ) U 1 .if 1^ N-S Current at 150M (cm/sec) Prediction of Tidal Excursions (M) wr 'i [-9 0 O •8 r»10 n 3 • 0 Ul -10 n Wind Record at Squamish (M/sec) Squamish River Discharge (M7sec) V o N •10 3 o « I L10 s 600 -300 £ n 0 CO ^3 COATING F i g u r e 12 91 DROP P-16 (HOWE 4.7, EAST SIDE) DROP P-]0 DROP P-12 DROP P-13 DROP P-14 DROP P-15 (HOWE 4) DROP P - l l (HOWE 3.8) .SILL Fi gure 1 3 Location of the temperature m i c r o s t r u c t u r e p r o f i l e s made during the November 1973 c r u i s e i n Howe Sound. F i g u r e 14 O v e r a l l p r o f i l e o f Drop P-10 F i g u r e ,15 O v e r a l l p r o f i l e o f Drop P - l l 94 F i g u r e 16 O v e r a l l p r o f i l e o f Drop P-12 F i g u r e 17 O v e r a l l p r o f i l e o f Drop P-13 F i g u r e 18 O v e r a l l p r o f i l e o f Drop P-14 F i g u r e 20 O v e r a l l p r o f i l e o f Drop P-16 i r 8.4 8.6 TEMPERATUFE (°C) i r + + + + + + + + + + I L 8,8 2.0 0.0 •2.( Gradient (C /m) F i g u r e 21 D e t a i l e d p r o f i l e from drop P-12, F i g u r e 22 D e t a i l e d p r o f i l e f rom drop P-12. F i g u r e 23 D e t a i l e d p r o f i l e from drop P-13, 102 W 1 1 1 TEMPERATURE ( C) 1 • 0 - 1 - 2 GRADIENT (C°/m) F i g u r e 24 D e t a i l e d p r o f i l e from drop P-13. 103 Figure 25 STD l o n g c h a n n e l s e c t i o n made on November 13,1973 i n Howe Sound's b o t h b a s i n s . 104 STD c r o s s c h a n n e l at s t a t i o n Howe 4 F i g u r e 26 s e c t i o n made on November 22,1973 ( I n n e r B a s i n ) . Q O O O O CM o o /—\ m o o tu •> oo i 5 o 00 v—' I 2 s o O F i g u r e 27 STD c r o s s c h a n n e l s e c t i o n made on No-vember 22,1973 a t s t a t i o n Howe 4.7 ( I n n e r B a s i n ) . 106 F i g u r e 28 L o c a t i o n o f t h e t e m p e r a t u r e m i c r o s t r u c t u r e p r o f i l e s made d u r i n g t h e F e b r u a r y 1974 c r u i s e i n Howe Sound. T E M P E R A T U R E C O R M S . GRADIENT lc°/m) M E A N G R A D I E N T ( c ' / m ) 110 F i g u r e 32 O v e r a l l p r o f i l e o f Drop 9 Figure 33 Overall profile of Drop 10 112 TEMPERATURE R # M - S > VERTICAL Figure 34 Deep p a r t o f Drop 7 w i t h an expanded t e m p e r a t u r e s c a l e . 113 TEMPERATURE C ° c ) 7.5 7.7 7.9 ! 8.1 i R.M.S. VERTICAL GRADIENT (C°/m) 8.3 1.0 J ! J : I I l _ 200 F i g u r e 35 Deep p a r t o f Drop 8 w i t h an expanded t e m p e r a t u r e s c a l e . 114 Figure 36 Deep p a r t o f Drop 9 w i t h an expanded t e m p e r a t u r e s c a l e . 115 F i g u r e 37 Deep p a r t of Drop 10 w i t h an expanded t e m p e r a t u r e s c a l e . 116 Temperature ( C) 100 Depth (m) 150 J 200 250 F i g u r e 38 Comparison between t e m p e r a t u r e p r o f i l e s t a k e n two weeks b e f o r e and d u r i n g t h e F e b r u a r y 1974 m i c r o s t r u c t u r e c r u i s e . On t h e l e f t , p r o f i l e s f rom the O u t e r B a s i n : S t a t i o n Howe 3, J a n u a r y 22, 1974. R a m i l l e s C h a n n e l , F e b r u a r y 5, 1974. On t h e r i g h t , p r o f i l e s from t h e I n n e r B a s i n : S t a t i o n Howe 4.5, J a n u a r y 23, 1974. S t a t i o n Howe 4.5, F e b r u a r y 6, 1974. F i g u r e 39 STD l o n g c h a n n e l s e c t i o n made i n Howe Sound's I n n e r B a s i n on F e b r u a r y 6,1974. Figure 40 STD cross channel section made at st a t i o n Howe 4 on February 6, 1974. 119 I C '•H •a l r ~ v — — w i „ 0 0 i n o Figure 41 Detailed profile from Drop 6 Figure 42 Detailed profile from Drop 6. to o 121 F i g u r e 44 D e t a i l e d p r o f i l e from Drop 7 123 F i g u r e 45 D e t a i l e d p r o f i l e from Drop 7 F i g u r e 46 D e t a i l e d p r o f i l e from Drop 7 125 F i g u r e 47 D e t a i l e d p r o f i l e from Drop 8 126 F i g u r e 48 D e t a i l e d p r o f i l e f rom Drop 8 127 128 F i g u r e 50 D e t a i l e d p r o f i l e from Drop 9 129 F i g u r e 51 D e t a i l e d p r o f i l e f rom Drop 9 130 Figure 52 Detailed p r o f i l e from Drop 1 0 131 ^ m 4ruJ L o 132 F i g u r e 54 D e t a i l e d p r o f i l e from Drop 10 133 F i g u r e 55 D e t a i l e d p r o f i l e from the Deep Water of Drop 7 F i g u r e 56 t a i l e d p r o f i l e from the Deep Water of Drop 7 135 . i 1 --— E o u o F i g u r e 57 D e t a i l e d p r o f i l e from the Deep Water of Drop 8

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Temperature microstructure in Howe Sound Bilodeau, Laurent Ernest 1979

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