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Some oceanographic features of northern Chilean waters in July, 1962 Inostroza Villagra, Hector M. 1966

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SOME OCEANOGRAPHIC FEATURES OF. NORTHERN "CHILEAN WATERS IN JULY, 1962 by HECTOR M.^OSTROZACVILLAGRA 1 CK. E n g i n e e r , U n i v e r s i t y of C o n c e p c i o n , C h i l e , 1957 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF -MASTER OF SCIENCE i n t h e INSTITUTE OF OCEANOGRAPHY and DEPARTMENT OF PHYSICS We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF B R I T I S H COLUMBIA A P R I L , I 9 6 6 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r re ference and s tudy . I f u r t h e r agree that pe rmiss ion f o r e x t e n s i v e copy ing of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s . It i s understood that copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l ga in s h a l l not be a l lowed wi thout my w r i t t e n permiss ion I n s t i t u t e of O c e a n o g r a p h y and Phys i c s Department of The U n i v e r s i t y o f B r i t i s h Columbia Vancouver 8, Canada March 19 6 6 Date ABSTRACT A d e s c r i p t i o n i s p r e s e n t e d of some of the o c e a n o g r a p h i c f e a t u r e s of the n o r t h e r n C h i l e a n w a t e r s as i n d i c a t e d by a s t u d y of t h e d i s t r i b u t i o n of p r o p e r t i e s and of d i r e c t c u r r e n t m e a surements d u r i n g t h e M a r c h i l e I I E x p e d i t i o n , 1962• A-n a r r o w band of c o l d , low s a l i n i t y w a t e r of low o x y g e n c o n t e n t c l o s e t o t h e c o a s t ; an o x y g e n minimum l a y e r f r o m 50 t o 4^-00 m and t he permanence of t h e P e r u - C h i l e u n d e r c u r r e n t a r e t h e o u t s t a n d i n g f e a t u r e s of t h e a r e a . The p r o c e s s of u p w e l l i n g i s s u g g e s t e d as t h e main c a u s e of t h e d i s t r i b u t i o n of p r o p e r t i e s n e a r t h e c o a s t . However t h i s p r o c e s s of u p w e l l i n g was p r o b a b l y i n a q u i e s c e n t s t a t e d u r i n g t h e M a r c h i l e I I E x p e d i t i o n , b e i n g much l e s s i n t e n s e t h a n d u r i n g o t h e r e x p e d i t i o n s i n t h e same a r e a , and t h a n i n o t h e r s i m i l a r u p w e l l i n g r e g i o n s of t h e w o r l d . TABLE OF CONTENTS Page ABSTRACT i i LIST OF FIGURES v ACKNOWLEDGEMENTS v i i i INTRODUCTION I P r e v i o u s work 2 Methods 3 EXPEDITION PROGRAMME .., k PHYSICAL FEATURES OF AREA 6 C o a s t a l g e o g r a p h y and b o t t o m t o p o g r a p h y 6 M e t e o r o l o g y , 7 RESULTS 9 C u r r e n t s 9 O b s e r v e d d i s t r i b u t i o n of t e m p e r a t u r e s a l i n i t y and o x y g e n l i j . T e m p e r a t u r e .., l i j . S a l i n i t y 17 Oxygen . 19 S t a b i I i t y 2 0 D i s t r i b u t i o n of p r o p e r t i e s f r o m a d i f f e r e n t p o i n t of v i e w 2 1 T e m p e r a t u r e 2 2 Sa I i n i t y ., 2 3 Oxygen 2 3 Summary of p r o p e r t y d i s t r i b u t i o n s 2 J 4 . DISCUSSION , , 2 5 The w a t e r masses , 2 5 i v TABLE OF CONTENTS ( C o n t d . ) Page U p w e l l i n g - .' , - ............ 26 D i s t r i b u t i o n of p r o p e r t i e s an-d c u r r e n t s ,. 30 SUMMARY AND CONCLUSIONS i • 33 REFERENCES .. ; 35 APPENDIX 36 V L I S T OF FIGURES Page g. I : S t a t i o n C h a r t M a r c h i l e II E x p e d i t i o n i n J u l y 1962 - 58 g. 2: I n s e t t o S t a t i o n C h a r t 58 g. 3: M a i n f e a t u r e s of t h e b o t t o m t o p o g r a p h y 39 g. If.: Winds d u r i n g W i l l i a m S c o r e s b y E x p e d i t i o n i n 1931 • - ij.0 g. 5* Winds d u r i n g M a r c h i l e II E x p e d i t i o n I4.I g. 6: Dynamic t o p o g r a p h y of the s u r f a c e of t h e s e a w i t h r e s p e c t t o t h e 1000 db s u r f a c e ... \\Z g. 7: Dynamic t o p o g r a p h y a t the d e p t h of 50 m .... I4.3 g. 8: B y n a m i c t o p o g r a p h y a t t h e d e p t h of 100 m ... lu^ g. 9s Dynamic t o p o g r a p h y a t t h e d e p t h o f 250 m ..., hfi Dynamic t o p o g r a p h y a t t h e d e p t h of J+00 m ... lj.6 C u r r e n t s o f f A r i c a i i 7 C u r r e n t s o f f P t e . P a t a c h e J4.8 P e r u - C h i l e U n d e r c u r r e n t i|-9 Net of s t a t i o n s f o r g e o s t r o p h i c t r a n s p o r t .. 5^ G e o s t r o p h i c t r a n s p o r t i n S v e r d r u p s .......... 5 ' D i s t r i b u t i o n i n s u r f a c e t e m p e r a t u r e 52 D i s t r i b u t i o n of t e m p e r a t u r e i n P r o f i l e I4. . . . 53 D i s t r i b u t i o n of t e m p e r a t u r e i n P r o f i l e 3 . . . 53 D i s t r i b u t i o n of t e m p e r a t u r e i n P r o f i l e 5 • • • 5^f D i s t r i b u t i o n of. t e m p e r a t u r e a t the d e p t h of 100 m > 55 g. 21: D i s t r i b u t i o n of t e m p e r a t u r e a t t h e d e p t h of 250 m 56 g. 22: D i s t r i b u t i o n of t e m p e r a t u r e a t t h e d e p t h of lf.00 m • 57 10 12 g. 13 g. il+ 15 16 g. 17 g. 18 19 20 L I S T OF FIGURES ( C o n t d . ) Page F i g . 2 3 : D i s t r i b u t i o n of s u r f a c e s a l i n i t y ' 58 F i g . 2I4.: D i s t r i b u t i o n of s a l i n i t y a t t h e d e p t h of 50 m • 59 F i g . 25: D i s t r i b u t i o n of s a l i n i t y a t t h e d e p t h of 100 m 60 F i g . 26: D i s t r i b u t i o n of s a . l i n i t y a t the d e p t h of 250 m 61 F i g . 27: D i s t r i b u t i o n of s a l i n i t y a t t h e d e p t h of 14,00 m ..• 62 F i g . 28: D i s t r i b u t i o n of s a l i n i t y i n P r o f i l e I 63 F i g . 29: D i s t r i b u t i o n of s a l i n i t y i n P r o f i l e 5 63 F i g . 30: D i s t r i b u t i o n of s a l i n i t y i n P r o f i l e 3 &h F i g . 3 1 : D i s t r i b u t i o n of o x y g e n c o n t e n t a t t h e s u r f a c e 65 F i g . 32: D i s t r i b u t i o n of o x y g e n c o n t e n t i n P r o f i l e I . 66 F i g . 33: D i s t r i b u t i o n of o x y g e n c o n t e n t i n P r o f i l e 5» 66 F i g . 3lj.: D i s t r i b u t i o n of o x y g e n c o n t e n t a t t h e d e p t h of 50 m 67 F i g . 3-5: D i s t r i b u t i o n of o x y g e n c o n t e n t i n P r o f i l e 3» 68 F i g . 36: D i s t r i b u t i o n of o x y g e n c o n t e n t a t the d e p t h of 100 m 69 F i g . 37: S t a b i l i t y i n the u p p e r 50 m l a y e r 70 F i g . 38: S t a b i l i t y i n the u p p e r 100 m l a y e r .. 71 F i g . 39: D e p t h s of m i x e d l a y e r 72 F i g . I4.O: E n v e l o p e s of i s o t h e r m s • 73 F i g . I4J : E n v e l o p e s of i s o h a l i n e s 73 F i g . i | 2 : The w a t e r masses 7l\. F i g . ij - 3 : T h r e e - d i m e n s i o n a l d i a g r a m of t h e w a t e r masses a. Water masses i n t h e u p p e r i+OO m 75 b. A n t a r c t i c i n t e r m e d i a t e w a t e r 75 - - • v i i L I S T OF FIGURES ( C o n t d . ) . . Page F i g . D i s t r i b u t i o n of t e m p e r a t u r e i n P r o f i l e 6 . . . . 76 F i g . 2 D i s t r i b u t i o n of s a l i n i t y i n P r o f i l e 6 . . . . . . . 76 F i g . J4.6: D i s t r i b u t i o n of o x y g e n c o n t e n t i n P r o f i l e 6 . 77 ACKNOWLEDGEMENTS The a u t h o r w i s h e s to th a n k D r . G. L. P i c k a r d , D i r e c t o r of t h e I n s t i t u t e of O c e a n o g r a p h y of the U n i v e r s i t y of B r i t i s h C o l u m b i a , f o r h i s c o n s t a n t a d v i c e and g u i d a n c e i n t h e c o u r s e of t h i s s t u d y , as w e l l as f o r h i s m a t e r i a l s u p p o r t t o f i n i s h h i s s t u d i e s i n C a n a d a ; t o D r . H. L. B a r r a l e s and J o s e S t u a r d o f o r t h e i r v a l u a b l e h e l p ; t o L i s a n d r o C h u e c a s f o r h i s c o - o p e r a t i o n i n g a t h e r i n g t h e d a t a and t o h i s w i f e f o r h e r k i n d d e d i c a t i o n . •INTRODUCTION The M a r c h i l e II E x p e d i t i o n as i t s name i m p l i e s , was t h e s e c o n d of a s e r i e s aimed a t g e t t i n g a p r e l i m i n a r y o c e a n o g r a p h i c v i e w of t h e o c e a n o f f C h i l e . In f a c t i n t h e summer of I 9 6 0 t h e M a r c h i l e I E x p e d i t i o n was a c c o m p l i s h e d , e x t e n d i n g f r o m 29° 57'S t o 1 0 ° 161S l a t i t u d e w i t h 15 o c e a n o g r a p h i c p r o f i l e s c o v e r i n g most of t h e C h i l e a n m a i n l a n d c o a s t . T h r e e C h i l e a n o r g a n i z a t i o n s s p o n s o r e d and a c c o m p l i s h e d t h e e x p e d i t i o n : t h e Navy, t h e H u n t i n g and F i s h e r i e s D e p a r t m e n t of the M i n i s t r y of A g r i c u l t u r e , w i t h German a s s i s t a n c e , and t h e U n i v e r s i t y of C o n c e p c i o n . The p r i m a r y p u r p o s e of t h i s e x p e d i t i o n was to f i l l t h e gap l e f t by o t h e r e x p e d i t i o n s i n t h e a r e a , e m p h a s i z i n g t h e o c e a n o g r a p h y and c u r r e n t m e a s u r e m e n t s . S a m p l e s of p h y t o - and z o o p l a n k t o n were a l s o t a k e n and b e n t h i c s t u d i e s were u n d e r t a k e n c l o s e t o t h e c o a s t . The M a r c h i l e II e x p e d i t i o n a r e a i n 1962 e x t e n d e d f r o m 18° 30'S t o 35° S. ( F i g . I ) . From 18° 20'S t o 20° 50'S most of t h e work p l a n n e d was c o m p l e t e d . In a d d i t i o n , f o r b a t h y m e t r i c r e a s o n s t h e v e s s e l had t o go t o San F e l i x and San A m b r o s i o I s l a n d s , g i v i n g an o p p o r t u n i t y t o make a l i n e of t e n more open s e a deep s t a t i o n s . From San F e l i x and San A m b r o s i o t o J u a n F e r n a n d e z I s l a n d b a t h y t h e r m o g r a p h s t a t i o n s were made c o v e r i n g most of t h e d i s t a n c e b e t ween t h e s e i s l a n d s . The o c e a n o g r a p h y c o n s i s t e d of s e r i a l 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 o x y g e n m e a s u r e m e n t s , c o m b i n e d w i t h b a t h y t h e r m o g r a -p h i c o b s e r v a t i o n s . The o x y g e n was t i t r a t e d on b o a r d and t h e s a l i n i t y i n t h e l a b o r a t o r y of t h e U n i v e r s i t y of C o n c e p c i o n by th e O x n e r t e c h n i q u e . The c u r r e n t s were measured u s i n g p a r a c h u t e d r o g u e s t r a c k e d by r a d a r . P r e v i o u s work The most c o m p l e t e a c c o u n t of the s c i e n t i f i c e x p l o r a t i o n of t h e s o u t h e r n and n o r t h e r n p a r t of t h i s a r e a was g i v e n by G u n t h e r (1936). T h i s work i s c o n s i d e r e d a c l a s s i c o n e, b e c a u s e i t i s t h e f i r s t s y s t e m a t i c s u r v e y e x t e n d i n g f r o m t h e E a s t e r n E q u a t o r i a l P a c i f i c (2° S l a t i t u d e ) t o t h e S o u t h P a c i f i c (1+8° S l a t i t u d e ) . T h i s work has an e x t e n s i v e d i s c u s s i o n of many a s p e c t s c o n c e r n e d w i t h t h e P e r u C u r r e n t S y s t e m , p a r t i c u l a r l y t h e c o a s t a l r e g i o n . The work was done from t h e " W i l l i a m S c o r e s b y " o f t h e D i s c o v e r y C o m m i t t e e i n E n g l a n d and i t s m a i n p u r p o s e was t o s u r v e y t h e P e r u C u r r e n t S y s t e m i n i t s r e l a t i o n to t h e m a r i n e b i o l o g i c a l e n v i r o n m e n t and i n i t s r e l a t i o n u l t i m a t e l y t o t h e r e s o u r c e s of t h e a r e a a f f e c t i n g the human p o p u l a t i o n c o n c e r n e d . In t h e C h i l e a n C o a s t s i x o c e a n o g r a p h i c s e c t i o n s were d o n e , f r o m 35° S t o 18° 30'S l a t i t u d e . T h e s e s e c t i o n s c o n s i s t e d of s e r i a l t e m p e r a t u r e , s a l i n i t y , o x y g e n and p h o s p h a t e m e a s u r e m e n t s c o m b i n e d w i t h p h y t o - and z o o p l a n k t o n s t u d i e s and a l s o w i t h m e a s u r e m e n t s of the d r i f t of the s h i p . From 1931 u n t i l i960 l i t t l e o c e a n o g r a p h i c work was done o f f t h e C h i l e a n c o a s t . However i n i960 t h r e e i m p o r t a n t e x p e d i t i o n s were a c c o m p l i s h e d : The M a r c h i l e I e x p e d i t i o n i n F e b r u a r y - M a r c h i960 c o v e r i n g t h e c e n t r a l and s o u t h e r n w a t e r s w i t h o b s e r v a t i o n s of t h e d i s t r i b u t i o n of t e m p e r a t u r e , s a l i n i t y , o x y g e n and b i o l o g i c a l s t u d i e s i n 15 s e c t i o n s of a p p r o x i m a t e l y 100 m i l e s l e n g t h . The C h i p e r e x p e d i t i o n i n M a r c h - A p r i l i960 w i t h s i x o c e a n o g r a p h i c p r o f i l e s i n C h i l e a n w a t e r s . The S t e p I E x p e d i t i o n w h i c h c o v e r e d a v e r y e x t e n s i v e a r e a i n t h e e a s t e r n p a r t of the S u b t r o p i c a l and T r o p i c a l P a c i f i c O c e a n . M e t h o d s The methods used i n the M a r c h i l e II e x p e d i t i o n were t h e u s u a l ones i n t h i s s o r t of work and c o n s i s t e d i n s e r i a l s a m p l i n g of t he w a t e r b e i n g s u r v e y e d f o r t e m p e r a t u r e , s a l i n i t y and o x y g e n measuremen t s . The t e m p e r a t u r e s were m e a s u r e d w i t h deep sea r e v e r s i n g t h e r m o m e t e r s , c o r r e c t e d on b o a r d . The a c c u r a c y of t h e s e m e a s u r e m e n t s i s e s t i m a t e d t o be o f the o r d e r of + 0 . 0 2°C. The s a l i n i t y was m e a s u r e d on s h o r e i n t h e L a b o r a t o r y o f the U n i v e r s i t y of C o n c e p c i o n u s i n g the t i t r a t i o n method and f o l l o w i n g t h e O x n e r t e c h n i q u e , w i t h an e s t i m a t e d a c c u r a c y o f + 0 . 0 2°/oo. The o x y g e n was t i t r a t e d on b o a r d u s i n g the W i n k l e r method, t o an e s t i m a t e d a c c u r a c y of + 0 .05 m l / l . k EXPEDITION PROGRAMME The c r u i s e p l a n of the e x p e d i t i o n i s shown i n F i g . I . The o c e a n o g r a p h y c o n s i s t e d of 62 s t a t i o n s d i s t r i b u t e d i n s i x p r o f i l e s as shown i n t h i s f i g u r e . B e f o r e t h e p r o f i l e I was s t a r t e d , on J u l y 10, 1962, t h e p a r a c h u t e d r o g u e m e a s u r e m e n t s were made i n t h e a r e a i n d i c a t e d by s q u a r e No. I . The o c e a n o g r a p h y s t a r t e d 2 days l a t e r , on J u l y 12, c o m b i n e d w i t h b i o l o g i c a l and b e n t h o n i c o b s e r v a t i o n s . The b e n t h o n i c o b s e r v a t i o n s were done c l o s e t o t h e c o a s t . F o l l o w i n g t h i s , c u r r e n t m e asurements were made i n p r o f i l e s I and 5« I t w a s t h o u g h t t h a t t h e b e s t c o n v e n i e n t d e p t h s f o d e t e c t s u b s u r f a c e c u r r e n t s w o u l d be 10, 100, 250 and 600m. T h e r e f o r e t h e d r o g u e s were s e n t t o t h e s e d e p t h s , w i t h a p r e v i o u s c h e c k o f t h e o x y g e n minimum l a y e r f o r w h i c h a few s t a t i o n s were done i n p r o f i l e I ( s t a t i o n s A, B and C) and s t a t i o n s D and E i n p r o f i I e 5• The p r o f i l e 5 was f i n i s h e d on J u l y 26, a f t e r w h i c h t h e l o n g p r o f i l e 6 was s t a r t e d . T h i s was d e s i g n e d m a i n l y t o o b t a i n an i d e a o f the o c e a n i c c o n d i t i o n s , t a k i n g a d v a n t a g e of t h e f a c t t h a t t h e Navy had to do some b a t h y m e t r i c work i n San F e l i x and San A m b r o s i o I s l a n d s ( i n c o n n e c t i o n w i t h t h e c o l l i s i o n o f a f r e i g h t e r w i t h t h e r o c k s o f t h e b o t t o m n e a r t h e m ) . The m a i n o c e a n o g r a p h i c s u r v e y c o m p r i s e d 5' o c e a n o g r a p h i c s t a t i o n s ahd',88 b a t h y t h e r m o g r a p h i c o n e s . The d e s c r i p t i on w i l l d a t a ( F i g . I and F i g . 2 ) . 5 be b a s e d a l m o s t e n t i r e l y on t h i s 6 PHYSICAL FEATURES OF AREA C o a s t a l g e o g r a p h y and b o t t o m t o p o g r a p h y The m a i n f e a t u r e s o f t h e b o t t o m t o p o g r a p h y a r e shown i n F i g . 3» T h e r e a r e f o u r b a s i n s , t h r e e of w h i c h a r e l o c a t e d c l o s e t o t h e c o a s t . The b a s i n No. I i s d e e p e r t h a n 5*000m r e a c h i n g t o a maximum of 5»^-95m« The b a s i n No. 2 i s more t h a n 6,000m, btk23m b e i n g t h e d e e p e s t . The b a s i n No. 3 i s the d e e p e s t o f a l l , r e a c h i n g 7f8i|i+m a s a maximum. The b a s i n No. lj. r e a c h e s 6,366m as a maximum. The c o n t i n e n t a l s h e l f as shown by t h e 200m i s o b a t h i s v e r y n a r r o w and a v e r a g e s f r o m 5 t o 10 m i l e s i n w i d t h , d i s a p p e a r i n g i n some p l a c e s . In l e s s t h a n 30 m i l e s f r o m the c o a s t t h e d e p t h s i n c r e a s e t o more t h a n 3»000m« The r e s t of th e a r e a i s of a u n i f o r m d e p t h of ab o u t l|.,000m. The c o n t i n e n t a l s h e l f i s a l i t t l e w i d e r s o u t h of I q u i q u e , r e a c h i n g a maximum f r o m l a n d of a b o u t 18 m i l e s i n P u n t a L a b o s . The l a n d t o t h e e a s t of t h e a r e a i s a d e s e r t . A f e a t u r e o f t h e t o p o g r a p h y i s the c o a s t a l r a n g e , w h i c h h e r e i s r a t h e r low compared t o t h e s o u t h e r n p a r t of t h e c o u n t r y . A t 1,600m M e j i l l o n e s H i l l t o t h e s o u t h of P i s a g u a i s t h e h i g h e s t p o i n t . The a v e r a g e d i s t a n c e f r o m t h e c o a s t t o t h e Los Andes Range i s of t h e o r d e r of 80 t o 90 m i l e s . I t I s i n t e r e s t i n g t o n o t e t h a t t h e h i g h e s t m o u n t a i n i n the Los Andes Range i n C h i l e i s t h e A c o n c a g u a H i l l ( s h a r e d w i t h A r g e n t i n a ) w i t h a h e i g h t of 6,956m, w h i c h i s c e r t a i n l y l e s s t h a n the maximum d e p t h of 7>8^+m j u s t m e n t i o n e d . T h e r e f o r e t h i s p a r t of the c o u n t r y i s a n a r r o w band of l a n d b e t w e e n two m o u n t a i n r a n g e s , t h a t made someone s a y : " t h e C h i l e a n s have t o g r a b t h e L o s Andes n o t t o f a l l down i n t o t h e s e a " . The e x t e n s i o n of b a s i n s No. 2 and No. 3 t o w a r d s the n o r t h t o t h e P e r u C o a s t has been c a l l e d t h e P e r u - C h i l e T r e n c h , and i t i s c e r t a i n l y c o n s i d e r e d one of the i m p o r t a n t f e a t u r e s of t h e S o u t h A m e r i c a n s e a b o t t o m t o p o g r a p h y . M e t e o r o I o g y P r e v i o u s w o r k e r s have d e s c r i b e d t he w i n d s y s t e m i n t h e a r e a . The most d e t a i l e d s t u d i e s were t h o s e of G u n t h e r (I93&) a f t e r t h e " W i l l i a m S c o r e s b y " c r u i s e i n 1931. G u n t h e r s t u d i e d t h e w i n d d i s t r i b u t i o n f o r e v e r y two d e g r e e s of l a t i t u d e f r o m J+7° S fo 2° S i n the a r e a c o v e r e d by t h e c r u i s e . He a l s o gave an a c c o u n t of the w i n d s n e a r t h e c o a s t , t a k i n g the d a t a of t h e C h i l e a n M e t e o r o I o g i c a I O f f i c e f o r d i f f e r e n t p o i n t s on the c o a s t . He was a b l e t o g e t a good p i c t u r e of t h e w i n d s i n t h e r e g i o n . S u m m a r i z i n g , G u n t h e r ' s r e s u l t s a b o u t t h e w i n d s i t i s p o s s i b l e t o s a y t h a t t h e r e a r e two r e g i m e s i n the a r e a s u r v e y e d . One of them i s t h e open o c e a n r e g i m e where t h e w i n d s a r e m a i n l y t h o s e c o r r e s p o n d i n g to the S - E t r a d e s . The s e c o n d i s t h e c o a s t a l r e g i m e where t h e s e S - E t r a d e s a r e d e v i a t e d t o s o u t h e r l y and b l o w a l m o s t p a r a l l e l t o the c o a s t ( F i g . If.). The c o a s t a l w i n d s i n a d d i t i o n , s u f f e r d i u r n a l v a r i a t i o n s due to the p r e s e n c e of t h e l a n d , and o f t e n show e a s t e r l y o r w e s t e r l y c o m p o n e n t s , w h i c h g r e a t l y i n f l u e n c e t h e c u r r e n t s i n s h o r e . G u n t h e r a l s o n o t i c e d some s e a s o n a l v a r i a t i o n s i n b o t h d i r e c t i o n and m a g n i t u d e of t h e w i n d s , e s p e c i a l l y on t h e c o a s t a l r e g i o n . F u r t h e r w o r k e r s have e m p h a s i z e d and c o m p l e t e d the G u n t h e r a n a l y s i s and t h e work of B j e r k n e s , of the T r o p i c a l i n t e r a m e r i c a n Tuna Cornm i s s i o n } i s one o f the most c o m p l e t e f o r the E a s t e r n T r o p i c a l P a c i f i c and N o r t h e r n C h i l e . The w i n d o b s e r v e d d u r i n g t h e M a r c h i l e II E x p e d i t i o n i s i n d i c a t e d i n F i g . 5 & u s i n g t h e B e a u f o r t s c a l e . 'From t h i s F i g . 5 i t i s s e e n t h a t the w i n d s a r e v a r i a b l e and n o t s o s t r o n g as u s u a l , f e a t u r i n g c h i e f l y a s o u t h e r l y component of t h e w i n d . RESULTS C u r r e n t s From t h e v e r y i n t e r e s t i n g t r i p t h a t J u a n F e r n a n d e z made i n t h e s e c o n d h a l f of the S i x t e e n t h C e n t u r y ( E n c y c I o p e d i a B r i t a n n i c a ) , t h e q u e s t i o n of t h e s u r f a c e c u r r e n t s i n t h i s p a r t of the P a c i f i c has been d i s c u s s e d v e r y much. E s s e n t i a l l y J u a n F e r n a n d e z g o i n g f r o m L i m a t o V a l d i v i a d e c i d e d t o s a i l i n t h e open s e a . T h e r e f o r e he t r a v e l l e d s o u t h i n t h e open o c e a n and s u r p r i s i n g l y enough f o r him and h i s c r e w , he was a b l e t o r e a c h V a l d i v i a i n a p p r o x i m a t e l y h a l f t h e t i m e t h a t t h e v e s s e l s commonly took when s a i l i n g c l o s e r i n s h o r e . L a t e r w o r k e r s i n c l u d i n g H umboldt and many o t h e r s b e f o r e I 9 3 I h a v e d i s c u s s e d e x t e n s i v e l y the p r o b l e m of t h e s u r f a c e c u r r e n t s i n t h i s r e g i o n . The most c o m p l e t e a c c o u n t of t h e c u r r e n t s t o 193' was g i v e n by G u n t h e r ( 1936) . G u n t h e r o b s e r v e d the c u r r e n t s t h r o u g h the d r i f t of the s h i p s i m u l t a n e o u s l y t a k i n g c a r e f u l w i n d o b s e r v a t i ons . As a r e s u l t of h i s work and t h a t of o t h e r s , t h e p a t t e r n of t h e s u r f a c e c i r c u l a t i o n i n t h i s p a r t of the o c e a n became c l e a r e r . The c o n s p i c u o u s f e a t u r e i s t h e r e l a t i v e l y s t r o n g c u r r e n t n e a r t h e c o a s t f l o w i n g t o t h e n o r t h w i t h a weaker c u r r e n t o f f s h o r e a l s o t o t h e n o r t h b u t d e v i a t i n g t o w a r d t h e west a p p r o a c h i n g t h e P e r u - C h i l e B o r d e r . ( T h i s was c e r t a i n l y what made J u a n F e r n a n d e z t r i p t o the S o u t h much f a s t e r ) . . . . . . | 0 The S t e p I e x p e d i t i o n has shown t h a t t h e c u r r e n t s a l o n g C h i l e and P e r u a r e e s s e n t i a l l y d i f f e r e n t c u r r e n t s and t h a t t h e r e i s a s e p a r a t i o n b e t w e e n them. ( W o o s t e r , I960) The work done i n the M a r c h i l e II E x p e d i t i o n was l i m i t e d t o an a r e a of 100 x 135 m i l e s ( t h e m a i n p a r t ) and was e s s e n t i a l l y a d e t a i l e d o c e a n o g r a p h i c s u r v e y w i t h d i r e c t c u r r e n t m e a s u r e m e n t s i n p r o f i l e s I and 5« B e f o r e d e s c r i b i n g t h e c u r r e n t s as f o u n d w i t h p a r a c h u t e d r o g u e s , I w i l l d e s c r i b e t h e g e o s t r o p h i c c u r r e n t s c a l c u l a t e d , t a k i n g as r e f e r e n c e the 1,000 db s u r f a c e . T h i s has been t a k e n as a r e f e r e n c e s u r f a c e b e c a u s e i t has been f o u n d t h a t t h e • d i s t r i b u t i o n of p r o p e r t i e s a t t h e 1,000m d e p t h a r e h o r i z o n t a l l y s t r a t i f i e d , s u g g e s t i n g m i n i m a I , m o t i o n . I t s h o u l d be m e n t i o n e d t h a t t h e d y n a m i c h e i g h t c a l c u l a t i o n s were done u s i n g t h e t h e r m o s t e r i c a n o m a l y , s i n c e t h e d e n s i t y i s a l m o s t e n t i r e l y d e t e r m i n e d by t e m p e r a t u r e i n t h i s r e g i o n . The d y n a m i c t o p o g r a p h y of t h e s e a s u r f a c e w i t h r e f e r e n c e t o the 1,000 db s u r f a c e ( F i g . 6) i l l u s t r a t e s t h a t t h e r e a r e f o u r c e n t e r s where the s t r e a m l i n e s show an e d d y - l i k e c i r c u l a t i o n . One of t h e s e e d d i e s ( n e a r s t a t i o n 15) i s of a r a t h e r l a r g e h o r i z o n t a l e x t e n t and r e l a t i v e t o t h e o t h e r s t he v e l o c i t y a p p e a r s to be l a r g e r . A l m o s t the same p a t t e r n t o t h a t a t t h e s u r f a c e i s r e p r o d u c e d a t 50 m ( F i g . 7) where a g a i n a t s t a t i o n 15 the c u r r e n t s a r e s t r o n g e r . A t 100 m the c u r r e n t s a r e s i m i l a r t o t h o s e a t t h e s u r f a c e i n the o f f s h o r e r e g i o n . In t h e i n s h o r e r e g i o n a t t h e s u r f a c e and 50 rn t h e r e i s a c o u n t e r c u r r e n t > g o i ng t o t h e souith ( F i g . 8 ) . At 250 m ( F i g . 9) and lj.00 m ( F i g . 10) the o f f s h o r e c u r r e n t s a r e r e p e a t e d b u t a r e l e s s s t r o n g t h a n i n t h e u p p e r l a y e r s . A t t h e s e d e p t h s the u n d e r c u r r e n t g o i n g s o u t h i s s t i l l p r e s e n t a t d i s t a n c e s of l e s s t h a n 25 m i l e s from t h e c o a s t . The d i r e c t c u r r e n t m e a s u r e m e n t s show an a g r e e m e n t w i t h t h e g e o s t r o p h i c ones i n t h e s e c t i o n o f f A r ' i c a ( F i g . 1,1) a t 10 , 100 and 250 m. In t h e s e c t i o n o f f P u n t a P a t a c h e t h e r e a p p e a r s to be a g r e e m e n t between g e o s t r o p h i c c u r r e n t and d i r e c t m e a s u r e m e n t s a t 10 and 250 m. A t 100 and 1+00 m t h i s a g r e e m e n t i s n o t so c l e a r . However i t i s i n t e r e s t i n g to n o t e t h a t a t 250 m t h e p a r a c h u t e d r o g u e s seem t o d i v e r g e , b e c a u s e one of the d r o g u e s went to t h e s o u t h and t h e o t h e r t o the n o r t h . T h e r e f o r e t h i s w o u l d a l s o show t h e p o s s i b i l i t y of an a g r e e m e n t w i t h t h e g e o s t r o p h i c c u r r e n t s i n t h i s a r e a ( F i g . 12). The f l o w t o w a r d s t h e s o u t h of t h e u n d e r c u r r e n t was f u r t h e r e v i d e n c e d by t h e f i n d i n g of one of t h e d r o g u e s ( a t 250 m d e p t h ) 75 m i l e s t o t h e s o u t h , I J days a f t e r t he M a r c h i l e II m e a surements were done ( F i g . 13)• The d y n a m i c t o p o g r a p h y w i t h r e f e r e n c e t o t h e 500 db s u r f a c e has a l s o been c a l c u l a t e d f o r 10, 50, '00, 250 and lj.00 m. T h e s e c h a r t s do not show s u c h a good a g r e e m e n t b e t w e e n t h e d i r e c t m e a surements and the g e o s t r o p h i c c u r r e n t s . In f a c t , a t 10 m t h e g e o s t r o p h i c c u r r e n t s ( r e l a t i v e to 500 db) o f f A r i c a go i n t h e o p p o s i t e d i r e c t i o n t o t h e d i r e c t o n e s . The same t h i n g h appens a t 250 m. In t h e s e c t i o n o f f P u n t a P a t a c h e t h e a g r e e m e n t i s more v a g u e . I t i s t h e r e f o r e c o n s i d e r e d t h a t t h e r e a r e s i g n i f i c a n t c u r r e n t s b e l o w 500 db. As a c o n c l u s i o n , t h e c u r r e n t s i n t h i s a r e a f o l l o w a -r a t h e r c o m p l i c a t e d p a t t e r n . However t h e P e r u - C h i l e U n d e r c u r r e n t ( W o o s t e r and G i l m a r t i n , I96>l); w h i c h B r a n d h o r s t c a l l s t h e G u n t h e r c u r r e n t (I959)» i s a l w a y s p r e s e n t . I t i s a l s o p o s s i b l e t o s t a t e t h a t t h e o f f s h o r e c u r r e n t s a p p e a r t o be d i f f e r e n t f r o m t h e i n s h o r e o n e s . However the p o s s i b i l i t y t h a t t h i s c u r r e n t p a t t e r n as a w h o l e i s a p e r m a n e n t one, s t i l l r e m a i n s t o be s e e n , i n s p i t e o f t h e f a c t t h a t the P e r u - C h i l e U n d e r c u r r e n t i s t h e r e . F i n a l l y t h e a g r e e m e n t between g e o s t r o p h i c and r e a l c u r r e n t s s u g g e s t s t h a t t h e f l o w i n t h i s a r e a i s m a i n l y g e o s t r o p h i c . As t h i s i s so t h e g e o s t r o p h i c volume t r a n s p o r t of t h e u p p e r 1,000 m was c a l c u l a t e d f o l l o w i n g t h e t e c h n i q u e g i v e n by A. J a k h e l I n (I936) . The n e t of s t a t i o n s i s shown i n F i g . Ilj., and t h e t r a n s p o r t i t s e l f has been c a l c u l a t e d d i r e c t l y u s i n g f o r m u l a (12) of A. J a k h e l I n (1936), and t h e t h e r m o s t e r i c anomaly t a k e n f r o m the T - S d i a g r a m s f o r each s t a t i o n i n v o l v e d f o r t h e d y n a m i c h e i g h t s . The d i f f e r e n t d ynamic h e i g h t s h a v e been e x p r e s s e d i n d y n amic cm f o l l o w i n g Montgomery and W o o s f e r {\95k)» The t r a n s p o r t between two n e i g h b o r s t a t i o n s has been c a l c u l a t e d i n t h i s way, and t h e n the n e x t p a i r , u n t i l e v e r y p r o f i l e f r o m I t o 5 was c o m p l e t e d . In a d d i t i o n , two m e r i d i o n a l p r o f i l e s have been a l s o c a l c u l a t e d and t h e y a r e shown i n F i g . 1 I 4 . . A f t e r each p r o f i l e was c a l c u l a t e d , t h e t r a n s p o r t p e r p e n d i c u l a r t o t h e l i n e of s t a t i o n s was a v e r a g e d f o r each p r o f i I e . A f t e r c o m p l e t i n g t h e f i v e n o r t h - s o u t h p r o f i l e s and t h e two e a s t - w e s t ones a t h r e e d i m e n s i o n a l d i a g r a m has been p r e p a r e d s h o w i n g t h e o v e r a l l volume g e o s t r o p h i c t r a n s p o r t ( F i g . I 5 ) » As a summary I.7 S v e r d r u p ( I S v e r d r u p = I m i l l i o n c u b i c m e t r e s p e r s e c o n d ) f l o w t o w a r d s t h e n o r t h and 2.2 S v e r d r u p t o w a r d the w e s t . These r e s u l t s a l s o w o u l d show a s m a l l v e r t i c a l upwards m o t i o n of t h e o r d e r of 3 m/month i n t h e a r e a as a w h o l e . A s t u d y of the i n f l u e n c e of i n t e r n a l waves on the c u r r e n t s of t h i s a r e a was a l s o done, f o l l o w i n g t h e t e c h n i q u e g i v e n by M. R a t t r a y (1959)* The r e s u l t s of t h e s e s t u d i e s were n e g a t i v e . In o t h e r words i t i s n o t p o s s i b l e t o d e t e c t any s i g n i f i c a n t i n f l u e n c e of i n t e r n a l waves, o r c u r r e n t s , a c c o r d i n g t o the d a t a a n a l y s e d . - - - • \k O b s e r v e d d i s t r i b u t i o n of t e m p e r a t u r e , s a l i n i t y and o x y g e n The t e m p e r a t u r e and s a l i n i t y have been p l o t t e d and v e r i f i e d i n t h e u s u a l way i n t h e T - S d i a g r a m . F i v e p r o f i l e s of t e m p e r a t u r e and s a l i n i t y h a v e been p r e p a r e d c o r r e s p o n d i n g t o t h e o c e a n o g r a p h i c p r o f i l e s shown i n F i g . I . In a d d i t i o n to t h i s t h e p r o f i l e s f o r s e c t i o n 6 have a l s o been p r e p a r e d . F o r t h i s p u r p o s e the v a l u e s of t e m p e r a t u r e o r s a l i n i t y t h a t f i t t he T - S c u r v e s have been u s e d . Those p o i n t s n o t f i t t i n g t h e c u r v e s have been d i s r e g a r d e d as u n r e I i ab I e . The o x y g e n has been p l o t t e d a g a i n s t t e m p e r a t u r e i n the T - S d i a g r a m s and the p r o f i l e s h ave been p r e p a r e d i n a s i m i l a r way t o t h o s e of t e m p e r a t u r e and s a l i n i t y . When t h e v e r t i c a l p r o f i l e s had been p r e p a r e d , h o r i z o n t a l s e c t i o n s of t h e s e t h r e e p r o p e r t i e s were p r e p a r e d , f o r t h e s u r f a c e s a t 0, 50, 100, 250 and i+00 m d e p t h . The f e a t u r e s f o u n d a r e d i s c u s s e d s e p a r a t e l y f o r e a c h p r o p e r t y . Tempera t u r e I t was d e c i d e d not t o r e p r o d u c e a l l t h e s e c t i o n s i n t h i s a c c o u n t , b u t some of the t y p i c a l ones s h o w i n g most c l e a r l y the o c e a n o g r a p h i c f e a t u r e s . The t e m p e r a t u r e p r o f i l e s have been of o c e a n o g r a p h i c and b a t h y t h e r m o g r a p h i c a r e a n a l y s e d i n the f o l l o w i n g p a g e s . p r e p a r e d f r o m d a t a s t a t i o n s , and t h e y • - • 15 The f i r s t f e a t u r e o b s e r v e d i s a band of c o l d w a t e r a t th e s u r f a c e ( F i g . 16), c l o s e t o t h e c o a s t ( a b o u t 6 m i l e s ) of i r r e g u l a r and v a r i a b l e w i d t h , w h i c h shows a minimum a t P u n t a M a d r i d . The I6°C i s o t h e r m r u n s p a r a l l e l t o the c o a s t and c l o s e t o i t , w h i l e t h e I7°C i s o t h e r m i s i r r e g u l a r and s e p a r a t e s t h e c o l d w a t e r c l o s e t o s h o r e f r o m the warmer w a t e r o f f s h o r e , where a maximum of 17•81°C ( s t a t i o n 9) w a s r e c o r d e d a t a b o u t "JO m i l e s f r o m t h e c o a s t . A p p r o x i m a t e l y \\.0% of t h e a r e a has a t e m p e r a t u r e b e l o w I7°C. In g e n e r a l , t h e r e i s a c l e a r l y d e f i n e d t h e r m o c l i n e b u t t h e t e m p e r a t u r e p r o f i l e s show t h a t t h e r e i s a r a t h e r n a r r o w band of l e s s t h a n 10 m i l e s w i d t h f r o m t h e c o a s t where the t h e r m o c l i n e i s not s o d i s t i n c t ( F i g . |6). P r o f i l e !(. ( F i g . 17) shows t h a t t h e t h e r m o c l i n e becomes w e l l e s t a b l i s h e d a t a d i s t a n c e of 60 m i l e s f r o m t h e c o a s t . P r o f i l e 3 ( F i g . 18) shows t h a t t h e r e i s a s m a l l t h e r m o c l i n e n e a r t h e c o a s t (10-20 m i l e s ) , t h e n i t i s i n t e r r u p t e d a p p e a r i n g a g a i n a t a b o u t JO m i l e s . P r o f i l e 5 ( F i g . 19) shows a l e s s d i s t i n c t t h e r m o c l i n e a t a b o u t 10 m i l e s f r o m t h e c o a s t and e x t e n d i n g o f f s h o r e . P r o f i l e s I ( n o t r e p r o d u c e d ) , 3 a n d k- ( F i g . 18 and 17) show a s h a r p t h e r m o c l i n e o f f t h e c o a s t a t a b o u t 5° m d e p t h . T h i s s h a r p t h e r m o c l i n e shows a maximum d e p t h of a b o u t 70 m i n p r o f i l e 3 ( F i g . 18) a t a l i t t l e more t h a n 100 m i l e s f r o m t h e c o a s t . , , - 16 The minimum d e p t h of t h e t h e r m o c l i n e i s i n p r o f i l e I a t a b o u t 20 - 30 m a t 27 m i l e s f r o m t h e c o a s t . A l l t h e p r o f i l e s show an uneven d i s t r i b u t i o n of t e m p e r a t u r e f r o m t he s u r f a c e t o a l i t t l e more t h a n lj.00 - 500 m « B e l o w t h i s d e p t h t he w a t e r becomes h o r i z o n t a l l y s t r a t i f i e d w i t h s m a l l e r t e m p e r a t u r e g r a d i e n t s , d e c r e a s i n g t o w a r d s g r e a t e r d e p t h s . T h e r e f o r e most of t h e v a r i a t i o n s i n t e m p e r a t u r e a r e r e c o r d e d i n t h e u p p e r 500 m » H o r i z o n t a l d i s t r i b u t i o n s of t e m p e r a t u r e show t h a t a t 10 m t h e r e i s e s s e n t i a l l y the same d i s t r i b u t i o n as a t the s u r f a c e . The same i s t r u e a t 20 m. The 50 m s e c t i o n shows a v e r y d i s t i n c t maximum t e m p e r a t u r e r e g i o n c o v e r i n g the o u t s i d e a r e a w i t h v a l u e s as h i g h '.; as I7°C, s i m i l a r t o t h o s e a t t h e s u r f a c e . At 100 m ( F i g . 20) the s e c t i o n shows t h a t the maximum of t e m p e r a t u r e i s s t i l l p r e s e n t but i s now a t a b o u t 30 m i l e s f r o m t h e c o a s t and r u n n i n g somewhat p a r a l l e l t o i 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 a t 250 m ( F i g . 21) shows a r a t h e r u n i f o r m t e m p e r a t u r e o v e r the w h o l e a r e a w i t h a s m a l l minimum t e m p e r a t u r e r e g i o n i n the s o u t h and a s m a l l maximum i n the n o r t h . At ij,00 m ( F i g . 22) t h e r e i s s t i l l a maximum of t e m p e r a t u r e p r e s e n t c l o s e s t to the c o a s t i n the n o r t h and r e a c h i n g t h e o f f s h o r e b o r d e r i n the s o u t h . 17 S a l i n i t y The maximum s a l i n i t y o b s e r v e d i n the s u r f a c e was 3 5 « 2 I ° / 0 0 i n p r o f i l e 3 ( s t a t i o n 3 0 ) . The minimum of ^l\.,6^°/oo was f o u n d n e a r t h e c o a s t i n p r o f i l e 1+ ( s t a t i o n 1+0). Two d i s t i n c t r e g i o n s a r e o b s e r v e d i n the s u r f a c e ( F i g . 2 3 ) ; the a r e a i s d i v i d e d a p p r o x i m a t e l y i n h a l f by the i s o h a l i n e 3l4-.90/°o» w h i c h s e p a r a t e s the c o a s t a l a r e a of l o w e r s a l i n i t y , f r o m t h e more o c e a n i c one of h i g h e r s a l i n i t y . The low s a l i n i t y c o a s t a l a r e a a p p e a r s t o s p r e a d o f f s h o r e i n p r o f i l e 1+, where St r e a c h e s a w i d t h of a b o u t 60 m i l e s ; i t e x t e n d s a l o n g t h e c o a s t i n s e c t i o n s I , 2 and 3» T h i s c o n f i g u r a t i o n s u g g e s t s t h a t t h e c e n t e r of h i g h s a l i n i t y i s i n the c e n t r a l p a r t of the r e g i o n and i t a c t s as a s o u r c e of h i g h s a l i n i t y w a t e r c oming f r o m t h e open o c e a n . T h i s i s a f e a t u r e a l r e a d y n o t i c e d by W o o s t e r ( I960) . T h e r e f o r e c o r r e s p o n d i n g t o t h e low t e m p e r a t u r e band n e a r t h e s h o r e and h i g h e r t e m p e r a t u r e s o f f s h o r e , a r e low s a l i n i t i e s i n s h o r e and h i g h e r ones o f f s h o r e . The d i s t r i b u t i o n of s a l i n i t y a t 5° m ( F i g . 2ij.) i s i n t e r e s t i n g . I t r e v e a l s a r e g i o n of minimum { < *>}±.!j0/oo) s e p a r a t i n g two maxima. One of the maxima i s c l o s e t o t h e c o a s t and i t s w i d t h i s a b o u t 1+5 m i l e s ; i t s v a l u e v a r i e s f r o m 3i|..7 0/o° t o 3l4-.8°/oo i n the s o u t h , but c l o s e to t h e c o a s t i t r e m a i n s a l m o s t c o n s t a n t a t 3 i| . .8 0/°o. A t 100 m ( F i g . 25) a v e r y c l e a r maximum of 3^-«9°/°° i s n o t i c e d a l o n g t h e c o a s t s p r e a d i n g f r o m 5 m i l e s t o a b o u t I4.5 m i l e s f r o m i t . The minimum r e a c h e s l e s s t h a n 3 I J . . 6 0 / 0 0 i n p r o f i l e 3 o f f the c o a s t . At 250 m,-(Fig. 26) the s a l i n i t y i s r a t h e r u n i f o r m w i t h a v a l u e of 3^-«8°/oo. At 1|00 m ( F i g . 27) t h e s a l i n i t y i s a g a i n a l m o s t u n i f o r m , and o v e r most o f t h e a r e a has a v a l u e of 3^-«7°/o°» The d i f f e r e n t h o r i z o n t a l s e c t i o n s show a c o a s t a l r e g i o n where s a l i n i t y i s r a t h e r u n i f o r m l y d i s t r i b u t e d i n a c o a s t a l band of a b o u t 10 m i l e s w i d t h . A t o n g u e of minimum s a l i n i t y ( F i g . 28) i s o b s e r v e d i n the o u t e r p a r t , w i t h v a l u e s as low as 3k-»h°/oo and l e s s ( > 3l4-.3°/oo) • The d e p t h of t h e c o r e of t h i s t o n g u e a p p e a r s t o be 50 m t o 70 m » T h i s t o n g u e i s v e r y s m a l l i n the b o r d e r of p r o f i l e I , b u t as i t goes s o u t h i t becomes more e x t e n d e d and d e e p e r u n t i I p r o f i l e 5 ( F i g * 29) where i t c o v e r s t h e e n t i r e e x t e n t f r o m t h e c o a s t and t o a d i s t a n c e o f 100 m i l e s . T h e r e e x i s t s i n t h e e n t i r e a r e a a maximum s a l i n i t y r e g i o n r e a c h i n g t h e v a l u e 3^-'9°/°° and g r e a t e r ( <35.0) c o v e r i n g most of i t ( F i g . 30) • T h i s maximum a p p e a r s t o be s e p a r a t e d by t h e 3^-»8°/°o i s o h a l i n e and i t s c o r e a p p r o a c h e s t h e c o a s t i n p r o f i l e s 2, 3 and 5* I t ' s a l s o n o t i c e a b l e t h a t t h e p r e s e n c e of t h i s maximum i s e v i d e n t more i n the c o a s t a l r e g i o n where i t i n f l u e n c e s t h e s a l i n i t y d i s t r i b u t i o n t o d e p t h s g r e a t e r t h a n 500 m. The p r e s e n c e of a minimum s a l i n i t y l a y e r b e l o w 500 m d e p t h i s a l s o n o t i c e a b l e . In p r o f i l e I ( F i g . 28) t h i s minimum i s shown t o be d e l i n e a t e d by. t h e i s o h a l i n e 3h*&°/00 (500 m t o 1,600 m d e p t h ) . In s e c t i o n 2 v a l u e s of 3i+»50/0 0 and l o w e r f o r m t h e s a l i n i t y minimum a t a b o u t 700 m. In s e c t i o n 3 ( F i g . 30) t h e minimum i s a t 800 m and i s of a g r e a t e r e x t e n t ' . At s t a t i o n 1|. and 5 t h i s l a y e r becomes d e e p e r and a l s o t h i c k e r . Oxygen Most of t h e s u r f a c e i s c o v e r e d by a l a y e r of more t h a n 5 m l / l i n o x y g e n c o n t e n t ( F i g . 31), b u t n e a r t h e c o a s t i n a l l s e c t i o n s t h e v a l u e of the o x y g e n c o n t e n t was l o w e r t h a n o f f s h o r e . T h i s band of low o x y g e n i s a b o u t 20 m i l e s w i d e i n p r o f i l e I , ( F i g . 32) and e x t e n d s u n i f o r m l y t o w a r d s t h e s o u t h w i t h a w i d t h of l e s s t h a n 10 m i l e s ( i n some c a s e s l e s s t h a n 5 m i l e s ) . In p r o f i l e s I and 5 ( F i g . 32 and 3$) t h i s low o x y g e n r e a c h e s v a l u e s l o w e r t h a n 1+.0 m l / l . A t 50 m ( F i g . 34) the low o x y g e n v a l u e s a r e n o t i c e a b l e n e a r the c o a s t where a v e r y e x t e n d e d a r e a to more t h a n 50 m i l e s i n p r o f i l e I t o 5 ( F i g . 32 and 33) w i t h v a l u e s as low as 0.25 m l / l i s p r e s e n t . A t t h i s d e p t h a maximum of o x y g e n Is p r e s e n t i n p r o f i l e 3 ( F i g . 35) i n t h e o u t e r edge of t h e a r e a . A t 100 m ( F i g . 36) t h e very low v a l u e of 0.25 m l / l has e x t e n d e d to most of the a r e a . However i n p r o f i l e 3 ( F i g . 35) a maximum of 2 m l / l i s o b s e r v e d a t 70 m i l e s f r o m the c o a s t . A t 250 rn the o x y g e n d i s t r i b u t i o n i s u n i f o r m and i t s v a l u e I e s s t h a n 0.25 m l / l . A t ij.00 m the d i s t r i b u t i o n i s the same as t h a t a t 250 m, bu t a s m a l l maximum of 0.5 m l / l i s p r e s e n t i n a l l s e c t i o n s , b e i n g g r e a t e r i n p r o f i l e 5 a n d a l m o s t d i s a p p e a r i n g i n p r o f i l e I ( F i g . $2 and 3 3 ) . The d i f f e r e n t p r o f i l e s show c l e a r l y t h a t t h e r e a r e t h r e e r e g i o n s as f a r as o x y g e n d i s t r i b u t i o n i s c o n c e r n e d . The f i r s t r e g i o n i s a c t u a l l y a l a y e r of a v e r y s t e e p o x y g e n g r a d i e n t . In p r o f i l e I ( F i g . 32) f r o m 20 t o 80 m the o x y g e n has f a l l e n t o v a l u e s of l e s s t h a n 0.25 m l / l . T h i s l a y e r becomes d e e p e r g o i n g s o u t h . In p r o f i l e 5 ( F i g . 33) the d e p t h r e a c h e s 60 m. B e l o w t h e w e l l o x y g e n a t e d s u r f a c e l a y e r comes a t h i c k l a y e r of p o o r l y o x y g e n a t e d w a t e r , b e c o m i n g a l m o s t c o m p l e t e l y d e p l e t e d i n a number of s t a t i o n s (0 .06 - 0.07 m l / l ) . T h i s l a y e r r e a c h e s 600 m and more c l o s e t o t h e c o a s t i n p r o f i l e I . The t h i c k n e s s of t h i s l a y e r d i m i n i s h e s g r a d u a l l y g o i n g t o t h e s o u t h , where i n p r o f i l e 5> i t r e a c h e s d e p t h s of ij-00 m. Under i+OO m t h e r e e x i s t s t h e t h i r d l a y e r where the o x y g e n a g a i n i n c r e a s e s . S e c o n d a r y m a x i m a i n o x y g e n a r e o b s e r v e d i n p r o f i l e s .3 and I4. a t a b o u t 1,600 m. S t a b i I i t y In a d d i t i o n t o the c h a r a c t e r i s t i c s a l r e a d y d i s c u s s e d , t h e s t a b i l i t y a t 50 m d e p t h i n the u p p e r l a y e r and t h a t a t 100 m has been c a l c u l a t e d and c h a r t e d ( F i g . 37 and 3 8 ) . 21 T h e r e i s g r e a t e r s t a b i l i t y i n t h e c o a s t a l a r e a ( a b o u t 25 m i l e s w i d e ) , and i n t h e a r e a as a w h o l e t he s t a b i l i t y a t 50 m i s h i g h e r t h a n t h a t a t 100 m. The maximum s t a b i l i t y was o b s e r v e d n e a r t h e c o a s t a t s t a t i o n 39 a n c i the minimum s t a b i l i t y was o b s e r v e d a t s t a t i o n 30 where t h e r e was i n s t a b i l i t y a t t h e 50 m l e v e l . The m i x e d l a y e r has a l s o been c h a r t e d ( F i g . 39) • Some of t h e c h a r a c t e r i s t i c s a r e : ( a ) .no m i x e d l a y e r n e a r the c o a s t j ( b ) a r e g i o n of a b o u t I4.O m i l e s w i d t h where the m i x e d l a y e r i s 20 m d e e p . In t h e r e s t of the a r e a t h e c o n v e c t i o n l a y e r i s d e e p e r w i t h i t s maximum v a l u e a t s t a t i o n 30* As a c o n c l u s i o n i t c a n be s t a t e d t h a t the c o n v e c t i o n l a y e r i s w e l l d e v e l o p e d o f f s h o r e and i l l - d e f i n e d o r a b s e n t n e a r s h o r e . D i s t r i b u t i o n of p r o p e r t i e s f r o m a d i f f e r e n t p o i n t of v i e w To g e t a mean p i c t u r e of t h e d i s t r i b u t i o n of p r o p e r t i e s i n t h i s a r e a , a d i f f e r e n t way of r e p r e s e n t a t i o n has been a t t e m p t e d and i s now d i s c u s s e d . The c o n d i t i o n s f r o m s o u t h t o n o r t h do not show any m a j o r c h a n g e , o r i n o t h e r words t h e r e a r e no s t r i k i n g d i f f e r e n c e s i n t e m p e r a t u r e , s a l i n i t y or oxygen c o n t e n t i n a h o r i z o n t a l p l a n e , b e c a u s e i n g e n e r a l t h e d i s t r i b u t i o n of p r o p e r t i e s s u g g e s t s a c e r t a i n u n i f o r m i t y of the a r e a as a w h o l e . In t h e s e c i r c u m s t a n c e s i t was t h o u g h t t h a t by t a k i n g t h e f i v e s e c t i o n s a l t o g e t h e r a mean p a t t e r n w o u l d be f o u n d , g i v i n g some i d e a of t h e g e n e r a l f e a t u r e s of t h e a r e a . To do t h i s , t h e f i v e s e c t i o n s of t e m p e r a t u r e , s a l i n i t y and o x y g e n were r e p r e s e n t e d t o g e t h e r i n one s i n g l e s h e e t f o r e a ch p r o p e r t y . A c o m p l e x of i s o l i n e s r e s u l t e d , b u t f r o m t h i s c o m p l e x a s i m p l i f i e d d i a g r a m has been o b t a i n e d f o r t h e d i s t r i b u t i o n of each p r o p e r t y . These a r e d i s c u s s e d s e p a r a t e l y Tempera t u r e In F i g . 1+0 t h e e n v e l o p e of d i f f e r e n t i s o t h e r m s has been drawn f r o m I3°C down t o 3 ° C . A few f e a t u r e s i m m e d i a t e l y become a p p a r e n t . In t h e f i r s t p l a c e t h e I3°C i s o t h e r m e n v e l o p e shows t h e r e g i o n where the t e m p e r a t u r e i s I3°C i n the a r e a as a w h o l e , and i t i s p o s s i b l e t o s e e t h a t t h i s r e g i o n r i s e s s l i g h t l y t o w a r d t h e c o a s t , s u g g e s t i n g t h a t t h e v e r t i c a l m o t i o n o f the w a t e r i s not l a r g e , but i n s t e a d t h e m o t i o n must be p r e d o m i n a n t l y h o r i z o n t a l . The 1 2 ° , 1 1 ° , I0°C r e g i o n s s u g g e s t t h a t t h e r e i s a c o n v e r g e n c e i n s t e a d of t h e d i v e r g e n c e c h a r a c t e r i s t i c of u p w e l l i n g . A n o t h e r f e a t u r e t h a t comes i n t o s i g h t i s t h e u n i f o r m i t y of t e m p e r a t u r e b e t w e e n 6 0 0 m and 9 0 0 m s u g g e s t i n g t h a t t h e b e s t r e f e r e n c e f o r g e o s t r o p h i c c o m p u t a t i o n s s h o u l d be a t a b o u t 8 0 0 m. In t h e c a l c u l a t i o n s a l r e a d y p r e s e n t e d t h e 1,000 db s u r f a c e was t.aken f o r g e o s t r o p h i c c a l c u l a t i o n s t o compare the r e s u l t s w i t h o t h e r s i n same a r e a ( W y ' r t k i , 1 9 6 3 ) . S a I i n 1 t y The s a l i n i t y e n v e l o p e s show a v e r y c l e a r p i c t u r e of t h e d i s t r i b u t i o n of t h e w a t e r masses i n the a r e a as a w h o l e . In t h e f i r s t p l a c e t h e p r e s e n c e of t h e S u b - A n t a r c t i c W a t e r l y i n g c l o s e to t h e s u r f a c e i s e v i d e n t i n F i g . 1+1. Below th:is.:water t h e S u b t r o p i c a l w a t e r i s p r e s e n t and t h e c o r e o f t h i s w a t e r w i t h a maximum s a l i n i t y i s e v i d e n t a t d e p t h s of 60 t o 200 m c l o s e t o t h e c o a s t . The minimum s a l i n i t y l a y e r f r o m 500 t o 1,100 m i s a l s o e v i d e n t i n F i g . 1+1 . P o s s i b l y t h e most i n t e r e s t i n g p o i n t i n t h i s r e p r e s e n t a t i o n i s t h a t t h e p r e s e n c e of t h e w a t e r masses " i n s i t u " i s i mmed i a t e l y e v i d e n t . Oxygen T h e r e a r e t h r e e r e g i o n s i n d i c a t e d by t h e e n v e l o p e s . The u p p e r l a y e r i s a r e g i o n of h i g h o x y g e n c o n t e n t and i t i s a l i t t l e d e e p e r o f f s h o r e where i t s d e p t h i s 80 m i n c o n t r a s t t o t h a t i n s h o r e of 1+0 m. The m i d d l e l a y e r i s a r e g i o n w i t h a v e r y low o x y g e n c o n t e n t and i t e x t e n d s f r o m 1+0 m t o 5OO-6OO m. The l o w e r l a y e r shows an i n c r e a s i n g o x y g e n c o n t e n t s h o w i n g e v e n t u a l l y a maximum of o x y g e n a t d e p t h s a l i t t l e l o w e r t h a n the A n t a r c t i c I n t e r m e d i a t e W a t e r . - . • 2k These r e s u l t s a r e i n a g r e e m e n t w i t h what has been a l r e a d y d e s c r i b e d , b u t have the a d v a n t a g e of s h o w i n g the o x y g e n d i s t r i b u t i o n " i n s i t u " of the a r e a as a w h o l e , w h i c h m i g h t be of i n t e r e s t f o r b i o l o g i s t s o r o t h e r s p e c i a l i s t s . Summary of p r o p e r t y d i s t r i b u t i o n s A c c o r d i n g t o what t he p r e s e n t d a t a shows, t h i s a r e a c a n be c o n s i d e r e d t o be composed of t h r e e l a y e r s : t h e f i r s t o n e , a s u r f a c e l a y e r , f r o m t h e s u r f a c e t o 50 - 80 m has a band of c o l d w a t e r of low s a l i n i t y and o x y g e n c o n t e n t of 10 m i l e s w i d t h , a l o n g the c o a s t , and w i t h a h i g h e r t e m p e r a t u r e , s a l i n i t y and o x y g e n o f f s h o r e , where a minimum s a l i n i t y i s p r e s e n t a t d e p t h s of 50 - 70 m. The t h e r m o c l i n e i s p r e s e n t i n t h i s l a y . e r , b u t i n -the c o a s t a l p a r t i s l e s s d i s t i n c t . The s e c o n d l a y e r has a c o r e of h i g h s a l i n i t y and a s s o c i a t e d w i t h i t a maximum of t e m p e r a t u r e and a minimum of o x y g e n c o n t e n t , r e a c h i n g d e p l e t i o n v a l u e s . I t l i e s f r o m 50 - 80 m t o more t h a n I4.OO m. The t h i r d l a y e r has a minimum of s a l i n i t y and e v e n t u a l l y a maximum of o x y g e n , b e i n g t h e r m a l l y s t r a t i f i e d . I t e x t e n d s f r o m 14.00 m t o more t h a n 2,000 m. DISCUSSION 25 The w a t e r masses The w a t e r masses i n the a r e a have been i d e n t i f i e d a c c o r d i n g t o t h e a c c e p t e d S v e r d r u p c l a s s i f i c a t i o n i\$l\2). In t h e a r e a c o v e r e d by t h e e x p e d i t i o n t h r e e v e r y d i s t i n c t w a t e r masses were o b s e r v e d ( F i g . 1+2). Near t h e s u r f a c e t h e r e i s a c l e a r minimum s a l i n i t y l a y e r wedge e x t e n d i n g f r o m t h e s o u t h t o w a r d s t h e n o r t h and a l m o s t d i s a p p e a r i n g i n p r o f i l e I , w i t h v a l u e s of 3i}..50/oo and l e s s ( > 3i+»4°/oo), whose e v o l u t i o n i s shown v e r y c l e a r l y i n t h e s a l i n i t y s e c t i o n s ( F i g . 1+3). T h i s minimum s a l i n i t y w a t e r i s v e r y c l o s e t o t h e s u r f a c e i n most of t h e p r o f i l e s and c o r r e s p o n d s t o S u b - A n t a r c t i c w a t e r . At t he s u r f a c e i n p r o f i l e I , and i n t h e o f f s h o r e r e g i o n s of p r o f i l e s 2 and 5» t h e r e i s a 2 o n e of h i g h s a l i n i t y r e a c h i n g v a l u e s of 35.20°'/oo and h i g h e r ( 3l|..30O/oo) ( F i g . 1+3). As shown b e f o r e i n the s a l i n i t y d i s t r i b u t i o n a t t h e s u r f a c e ( F i g . 23), t h e o r i g i n of t h i s w a t e r i s s u b t r o p i c a l . A c c o r d i n g to what has been f o u n d t h i s s u b t r o p i c a l w a t e r l i e s i n most s t a t i o n s n e a r the s u r f a c e , b u t a l s o a p p e a r s a t d e p t h s of 100 t o 300 m where t h e s a l i n i t y has been f o u n d t o be a maximum ( F i g . lj.3) . T h i s maximum s a l i n i t y a t t r i b u t e d t o s u b t r o p i c a l w a t e r a d v a n c e s t o w a r d s t h e s o u t h w i t h the P e r u - C h i l e U n d e r c u r r e n t and m i x e s g r a d u a l l y w i t h S u b - A n t a r c t i c o v e r l y i n g w a t e r . The t h i r d w a t e r mass p r e s e n t i n t h e a r e a i s t h e A n t a r c t i c I n t e r m e d i a t e w a t e r a t d e p t h s v a r y i n g f r o m 600 t o 1,000 m b e i n g d e e p e r i n p r o f i l e 5 ( F i g . 29) . T h i s i s p r e s e n t i n a l l t h e p r o f i l e s and r e a l l y i s an o u t s t a n d i n g f e a t u r e of t h i s a r e a . T h i s l a y e r of minimum s a l i n i t y i s e v e n t u a l l y a s s o c i a t e d w i t h a maximum o x y g e n l a y e r as i n p r o f i l e s lj. and 5 ( F i g * 36). Upwe M i n g So f a r , t h e o b s e r v e d d i s t r i b u t i o n s of p r o p e r t i e s have been d e s c r i b e d . In t h e f o l l o w i n g pages an a t t e m p t t o g i v e a p o s s i b l e e x p l a n a t i o n of the f a c t s w i l l be p r e s e n t e d . In t h e f i r s t p l a c e one c a n wonder why the band of c o l d w a t e r ©f r e l a t i v e l y l o w e r §aiinity and low o x y g e n i s p r e s e n t / a l o n g t h e c o a s t i n t h e u p p e r l a y e r . In t h e l i t e r a t u r e t h i s has been a t t r i b u t e d t o u p w e l l i n g of t h e s u b s u r f a c e w a t e r s . P o s s i b l y the c l e a r e s t e x a m p l e s of t h i s a r e g i v e n i n two s e c t i o n s o f f the C h i l e a n c o a s t (Gun toner, 1.9363) apd two s e c t i o n s o f f S o u t h West A f r i c a ( H a r t and C u r r i e , 1950) i n 193' and 1950 r e s p e c t i v e l y . By c o i n c i d e n c e b o t h e x p e d i t i o n s were c a r r i e d o u t f r o m the same s h i p , the " W i l l i a m S c o r e s b y " , A l t h o u g h i t i s p r o b a b l e t h a t u p w e l l i n g of s u b s u r f a c e w a t e r i s t h e p r i m e c a u s e of the c o l d low s a l i n i t y band a l o n g the c o a s t , o t h e r p o s s i b l e c a u s e s may be c o n s i d e r e d . One o t h e r p o s s i b l e c a u s e i s e v a p o r a t i o n . E v a p o r a t i o n of the s u r f a c e w a f e r s w i l l p r o d u c e a c o o l i n g e f f e c t and t h e r e f o r e l o w e r t e m p e r a t u r e s , b u t a t the same t i m e t h i s w i l l p r o d u c e a h i g h e r s a l i n i t y , w h i c h has not been o b s e r v e d n e a r the c o a s t . The b a t h y t h e r m o g r a p h i c d a t a shows t h a t t h e r e i s a n a r r o w band ( l e s s t h a n 10 m i l e s w i d e ) n e a r t h e c o a s t where the a i r t e m p e r a t u r e i s h i g h e r t h a n t h a t a t t h e s u r f a c e of t h e s e a . As the r e l a t i v e h u m i d i t y i n t h i s band i s of the o r d e r of 75% t h e r e i s a p o s s i b i l i t y t h a t some c o n d e n s a t i o n was t a k i n g p l a c e . In a d d i t i o n t h e a v e r a g e a i r - s e a t e m p e r a t u r e d i f f e r e n c e was 2.5 C° ( a i r t e m p e r a t u r e h i g h e r t h a n s e a s u r f a c e t e m p e r a t u r e ) . I f some c o n d e n s a t i o n were t a k i n g p l a c e t h i s w o u l d e x p l a i n t h e low s a l i n i t y n e a r t h e c o a s t , b u t i t w i l l n o t e x p l a i n the l o w e r t e m p e r a t u r e o b s e r v e d . I f some e v a p o r a t i o n were t a k i n g p l a c e o f f s h o r e , t h i s would e x p l a i n t he h i g h e r s a l i n i t y , b u t n o t t h e h i g h e r t e m p e r a t u r e . In o t h e r w o r d s , the p r o c e s s e s of e v a p o r a t i o n and c o n d e n s a t i o n m i g h t i n f l u e n c e t h e s a l i n i t y d i s t r i b u t i o n more t h a n the t e m p e r a t u r e d i s t r i b u t i o n . A n o t h e r c a u s e of low s a l i n i t y and low t e m p e r a t u r e n e a r t h e c o a s t s c o u l d be t h e r i v e r r u n o f f of c o l d w a t e r , as i n B r i t i s h C o l u m b i a c o a s t i n the N o r t h P a c i f i c , but t h e a r e a b e i n g d e s c r i b e d i s a d e s e r t and t h e r e f o r e t h i s w i l l n o t be a c a u s e . T h e r e f o r e the p r e s e n c e of c o l d w a t e r i n t h e c o a s t a l r e g i o n must be due t o a number of f a c t o r s i n w h i c h t h e most d e c i s i v e one must be t h e u p l i f t of c o l d w a t e r f r o m b e l o w , o r i n o t h e r w o r d s , t h e u p w e l l i n g . I f t h i s e x p l a n a t i o n i s c o r r e c t , one f u r t h e r s t e p w o u l d be t o compare i n some way the u p w e l i i n g i n the c o a s t d u r i n g t h e s u r v e y , w i t h t h e same p r o c e s s i n t h e same a r e a d u r i n g o t h e r e x p e d i t i o n s o r t h e same p r o c e s s i n o t h e r a r e a s . The f i r s t c o m p a r i s o n , w i t h what G u n t h e r f o u n d i n 193' , has been made w i t h t h r e e s e c t i o n s , t h o s e o f f C a l d e r a , A n t o f a g a s t a and A r i c a . To g e t an i d e a of what t h e c o n d i t i o n s w e r e , a d e t a i l e d a n a l y s i s of a l l f i v e s e c t i o n s of M a r c h i l e II E x p e d i t i o n has been done t a k i n g i n t o a c c o u n t the r i s i n g of i s o t h e r m s and i s o h a l i n e s t o w a r d t he c o a s t . The upward s l o p e of i s o t h e r m s and i s o h a l i n e s t o w a r d s t h e c o a s t f r o m o f f s h o r e w a t e r has been talke.n. • as an i n d e x . In t h i s way i t has been f o u n d , f o r i n s t a n c e , t h a t i n p r o f i l e I f r o m a b o u t "JO m i l e s o u t t o t h e c o a s t , t h e i s o t h e r m s r o s e 37 m i n t h e u p p e r l a y e r , and the i s o h a l i n e s r o s e 1+9 m. In a s i m i l a r way the f i v e p r o f i l e s have been e x a m i n e d and the r e s u l t s c a n be e x p r e s s e d as an a v e r a g e s l o p e of 0 .5 m / m i l e . I f t h i s i n d e x i s t a k e n as a c o m p a r a t i v e m e a s u r e , i n the G u n t h e r s e c t i o n s o f f C a l d e r a , A n t o f a g a s t a and A r i c a , t h e r e s u l t s w o u l d be: i n C a l d e r a t h e u p p e r l a y e r o f 100 m was r i s i n g a t a r a t e of 2.5 m / m i l e , o f f A n t o f a g a s t a a t I .3 m / m i l e and o f f A r i c a a t 1.1+ m / m i l e . These r e s u l t s w o u l d show t h a t t h e u p w e l i i n g d u r i n g M a r c h i l e II e x p e d i t i o n was l e s s i n t e n s e t h a n i n I93'» p o s s i b l y b e c a u s e t h e w i n d s were a l s o l e s s i n t e n s e d u r i n g M a r c h i l e I I . 29 In A r i c a t h e c o m p a r i s o n w o u l d show t h a t the u p w e l l i n g w o u l d be a l m o s t t h r e e t i m e s the one i n I9&2 f o r the u p p e r l a y e r . G u n t h e r has shown w i t h t e m p e r a t u r e and s a l i n i t y s e c t i o n s , t o g e t h e r w i t h o t h e r p r o p e r t i e s s u c h as o x y g e n and p h o s p h a t e s , t h e p r e s e n c e of u p w e l l i n g i n the t h r e e m e n t i o n e d s e c t i o n s o f f t h e C h i l e a n c o a s t . A l t h o u g h some of h i s c o n c l u s i o n s do n o t a g r e e w i t h o c e a n o g r a p h i c p r i n c i p l e s ( s i n k i n g of newly mtfcxed w a t e r a t C a l d e r a ) ( G u n t h e r , 1 9 3 ' ) , the p a t t e r n of u p w e l l i n g he d e s c r i b e s i s q u i t e c l e a r . To make s u r e t h a t t h e i n d e x shows s o m e t h i n g p o s i t i v e , t h e c o m p a r i s o n has been made w i t h two s e c t i o n s o f f S o u t h West A f r i c a t a k e n f r o m t h e " W i l l i a m S c o r e s b y " . T h e s e s e c t i o n s a r e t h e Orange R i v e r and S y l v i a H i ! I i o n e s . In the Orange R i v e r s e c t i o n t h e i n d e x was 0 . 7 m/mile i n t h e u p p e r 100 m l a y e r and i n S y l v i a H i l l 1.2 m / m i l e , s u g g e s t i n g t h a t i n t h i s a r e a t h e u p w e l l i n g was more i n t e n s e t h a n t h a t o b s e r v e d d u r i n g M a r c h i l e I I . A^ore e x a m p l e s come f r o m the A f r i c a n c o a s t m e n t i o n e d and t h e s e a r e c o n c e r n e d w i t h t h e f a c t t h a t i n S o u t h West A f r i c a i n the s e c t i o n s m e n t i o n e d t h e r e was no m i x i n g l a y e r p r e s e n t , and a l s o t h a t t h e u p w e l l i n g i n v o l v e d g r e a t e r d e p t h s , r e a c h i n g 2i|.0 m. In o t h e r w o r d s , t a k i n g t h i s i n t o a c c o u n t , t h e i n d e x i n Orange R i v e r w o u l d be I m / m i l e , and I . 3 m / m i l e i n S y l v i a H i l l . A n o t h e r i m p o r t a n t r e a s o n s h o w i n g the d i f f e r e n c e s b e t w e e n the two r e g i o n s i s t h a t o f f S o u t h West A f r i c a t h e s l o p e of , v . -.. - v ; - . , . 30 i s o t h e r m s and i s o h a l i n e s i n t h e u p p e r l a y e r was a l w a y s p o s i t i v e , b u t was n o t so o f f C h i l e where t h e r e were some f l u c t u a t i o n s of the i s o l i n e s i n t h e i r way up. In o t h e r words t h e i s o l i n e s ( t e m p e r a t u r e and s a l i n i t y ) r o s e s t e a d i l y f r o m o f f s h o r e t o the c o a s t f o r S o u t h West A f r i c a , where H a r t and C u r r i e ( 1 9 ^ 0 ) have shown w i t h d y n a m i c a r g u m e n t s t h a t t h e u p w e l i i n g was a t i t s maximum i n the s e c t i o n s a l r e a d y m e n t i o n e d , e s p e c i a l l y i n t h e Orange R i v e r o n e . I t s h o u l d a l s o be m e n t i o n e d t h a t i n the m i d d l e l a y e r d u r i n g M a r c h i l e I I , i . e . t h a t b e t w e e n 100 and i+OO - 500 m, t h e I s o t h e r m s t r e n d e d down as an a v e r a g e , b u t the i s o h a l i n e s t r e n d e d down i n t h e t h r e e n o r t h e r l y p r o f i l e s and up i n t h e two s o u t h e r l y o n e s . T h i s w o u l d s u g g e s t t h a t t h e r e i s d i v e r g e n c e of t h e u p p e r l a y e r s i n the t h r e e n o r t h e r l y p r o f i l e s and c o n v e r g e n c e i n t h e m i d d l e l a y e r , and t h a t i n t h e s o u t h e r l y two p r o f i l e s t h e r e i s d i v e r g e n c e i n b o t h u p p e r and l o w e r l a y e r s , w h i c h w o u l d have t o be t a k e n as a c o m p a r a t i v e l y h i g h e r u p w e l i i n g i n t h e two s o u t h e r l y t h a n i n t h e t h r e e n o r t h e r l y o n e s . D i s t r i b u t i o n of p r o p e r t i e s and c u r r e n t s In t h e m i d d l e l a y e r , t h e p r e s e n c e of a maximum s a l i n i t y c o r e w i t h maximum t e m p e r a t u r e and minimum o x y g e n , whose e v o l u t i o n c a n be t r a c e d f r o m N o r t h t o S o u t h i n the f i v e s e c t i o n s , c o u l d be a s s o c i a t e d w i t h the c u r r e n t s p r e s e n t i n t h e a r e a . I t has been shown i n the c u r r e n t d e s c r i p t i o n t h a t t h e s e a r e m a i n l y g e o s t r o p h i c on t h e a v e r a g e , and t h a t t h e u n d e r c u r r e n t to t h e s o u t h i s a l s o a g e o s t r o p h i c c o m p e n s a t i o n c u r r e n t . Now t h e s e c u r r e n t s c o m i n g f r o m t h e N o r t h t o t h e r e g i o n s t u d i e d b r i n g t h e p r o p e r t i e s b e l o n g i n g t o t h e i r o r i g i n ; i . e . s u b t r o p i c a l . In o t h e r w o r d s , i t i s t o be e x p e c t e d t h a t t h i s c o r e of h i g h s a l i n i t y and t e m p e r a t u r e and minimum o x y g e n i s due t o the p r e s e n c e o f S u b t r o p i c a l w a t e r b r o u g h t t o the a r e a by t h e P e r u - C h i l e U n d e r c u r r e n t . T h i s w o u l d e x p l a i n t h e d i s t r i b u t i o n o f p r o p e r t i e s f o u n d i n the m i d d l e l a y e r . Now f o r the l o w e r l a y e r f r o m i^OO - 500 m down t o 2,000 m and more, t h e p r e s e n c e of a minimum s a l i n i t y l a y e r a t d e p t h s between 800 - 1,000 m i s c o n s i s t e n t w i t h t h e g e n e r a l c l a s s i f i c a t i o n of w a t e r masses g i v e n by S v e r d r u p . In o t h e r w o r d s , t h e p r e s e n c e of the s a l i n i t y minimum l a y e r i s q u i t e r i g h t and i t i s where i t b e l o n g s t o o r where i s e x p e c t e d t o be, w i t h the a d d i t i o n a l f a c t t h a t i t s m i x t u r e i n the 135 m i l e s of l e n g t h c o v e r e d by t h e e x p e d i t i o n c o u l d be c e r t a i n l y t r a c e d . I t s h o u l d a l s o be m e n t i o n e d t h a t the p r e s e n c e of maxima i n t e m p e r a t u r e and s a l i n i t y and t h e minimum o x y g e n i n the m i d d l e l a y e r i s a l s o p r e s e n t i n p r o f i l e 6 ( F i g . [4,5 and s u g g e s t i n g t h a t the P e r u - C h i l e U n d e r c u r r e n t m i g h t r e a c h a d i s t a n c e of I4.OO m i l e s f r o m t h e c o a s t , as i t i s e v i d e n c e d i n F i g . iuj., F i g . ij . 5 , F i g . J4.6 a t s t a t i o n 59. . - - ... 32 The d e e p e r w a t e r s i n the a r e a were t r a c e d i n s t a t i o n s 10 and II of M a r c h i l e II and i t was f o u n d t h a t t h e s a l i n i t y r e m a i n s a l m o s t c o n s t a n t a t 3^-*67°/oo - 3I4..69 °/oo and t h e t e m p e r a t u r e a t l . 8 2 ° C . SUMMARY AND CONCLUSIONS 35 S u m m a r i z i n g t h e mai n f e a t u r e s c h a r a c t e r i z i n g t h e o c e a n o g r a p h y of t h i s r e g i o n , w h i c h have r e s u l t e d f r o m t h e a n a l y s i s of t h e d a t a of t h e M a r c h i l e II E x p e d i t i o n : 1. - The p r e s e n c e i n t h e a r e a of an up p e r l a y e r of 50 ~ 80 m t h i c k n e s s of c o l d w a t e r w i t h low s a l i n i t y and low o x y g e n c o n t e n t n e a r the c o a s t of t h e o r d e r of 5 m i l e s w i d t h . The p r e s e n c e of t h i s n a r r o w band i s due m a i n l y t o the u p w e l i i n g , a l t h o u g h some o t h e r p r o c e s s e s as e v a p o r a t i o n o r c o n d e n s a t i o n may a l s o c o n t r i b u t e . The p r o c e s s of u p w e l i i n g as f o u n d w o u l d s u g g e s t t h a t i t was i n a q u i e s c e n t s t a g e d u r i n g t h e p e r i o d of t h e M a r c h i l e II Exped i t i o n . 2 . - The p r e s e n c e of a m i d d l e l a y e r f r o m 50 ** 500 m d e p t h , w i t h a c o r e of h i g h s a l i n i t y , of r e l a t i v e l y h i g h t e m p e r a t u r e and low o x y g e n , a s s o c i a t e d m a i n l y w i t h t h e P e r u - C h i l e U n d e r c u r r e n t , has been f o u n d c l o s e t o the c o a s t , a l t h o u g h t h e p o s s i b i l i t y o f an e x t e n s i o n of t h i s U n d e r c u r r e n t t o w a r d the open s e a s h o u l d be k e p t i n m i n d . 3 . - A d e e p e r l a y e r b e l o w 500 m c o n t a i n i n g a s a l i n i t y minimum l a y e r t o d e p t h s of 600 - 1,000 m a s s o c i a t e d e v e n t u a l l y w i t h a maximum o x y g e n c o n t e n t . 1+.- E v i d e n c e f r o m deep s t a t i o n s shows the u n i f o r m v a l u 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 ,82°C and 31+.69 0 / 0 0 r e s p e c t i v e ! The p r e s e n c e of t h r e e w e l l d i f f e r e n t i a t e d w a t e r m a s s e s : S u b a n t a r c t i c Water m a i n l y i n t h e u p p e r l a y e r ; S u b t r o p i c a l Water i n t h e o f f s h o r e and n o r t h e r n p a r t of t h e a r e a and a s s o c i a t e d w i t h t h e P e r u - C h i l e U n d e r c u r r e n t ; and the A n t a r c t i c I n t e r m e d i a t e W a t e r c o n t a i n e d i n t h e s a l i n i t y minimum l a y e r d e s c r i b e d i n c o n c l u s i o n 3» The c u r r e n t s i n t h e a r e a a r e m a i n l y g e o s t r o p h i c and th e g e o s t r o p h i c voJume t r a n s p o r t t o w a r d t h e N o r t h i s 1.7 S v e r d r u p and t h a t t o w a r d t h e West i s 2.2 S v e r d r u p . 35 REFERENCES B j e r k n e s , J . , I96I: " E l N i n o S t u d y b a s e d on a n a l y s i s of o c e a n s u r f a c e t e m p e r a t u r e s 1935-57". i n t e r a m e r i c a n T r o p i c a l Tuna C o m m i s s i o n , V o l . V, No. 3 . La J 0 i l a , Ca I i f o r n i a . B r a n d h o r s t , W., 1959: " R e l a t i o n s h i p b e t w e e n t h e Hake F i s h e r y and a S o u t h e r n l y R e t u r n F l o w b e l o w t h e P e r u ' C u r r e n t o f f t h e C h i l e a n C o a s t " . . N a t u r e , V o l . 183, pp. 1832-3, L o n d o n . E n c y c l o p e d i a B r i t a n n i c a , 1910: C a m b r i d g e U n i v e r s i t y P r e s s , E l e v e n t h E d i t i o n , V o l . . 1 0 , p. 279. G u n t h e r , E. R.,. 1936: " A r e p o r t on o c e a n o g r a p h i ca I i n v e s t i g a t -i o n s i n t h e P e r u C o a s t a l C u r r e n t " . D i s c o v e r y R e p o r t s , V o l . 13, pp. I O 7 - 2 7 6 , C a m b r i d g e U n i v e r s i t y P r e s s . H a r t , T. J . , and R. I . C u r r i e , 196O: "The B e n g u e l a C u r r e n t " . . D i s c o v e r y R e p o r t s , V o l . 3'« PP« 123-298, C a m b r i d g e Uni v e r s i t y P r e s s . J a k h e l I n , A., 1936: "The w a t e r t r a n s p o r t of g r a d i e n t c u r r e n t s ' ! . G e o f y s i s k e Pub I i k a s j o n e r V o l . XI No. I I . Montogomery, R. B., and W. S. W o o s t e r , 195I+: "Thermos t e r i c Anomaly and the a n a l y s i s of s e r i a l o c e a n o g r a p h i c d a t a " . D e e p - S e a R e s . , 2, pp. 6 3 - 7 O . R a t t r a y , J r . , M., I95O: "On t h e C o a s t a l G e n e r a t i o n of I n t e r n a l . T i d e s " . T e l l u s . N o . I , i 9 6 0 . S v e r d r u p , H. U., M. W. J o h n s o n , and R. H. F l e m i n g , 19^2: "The Oc e a n s , f h e i r . P h y s i c s , C h e m i s t r y .and G e n e r a l B i o l o g y " . P r e n t i c e H a l l I n c . E n g l e w o o d C l i f f s , N. J . W o o s t e r , W. S., and M. G i l m a r t i n , 1961: "The P e r u - C h i l e U n d e r c u r r e n t " . J o u r n a l o f M a r i n e R e s e a r c h , V o l . 19, No. 3 , November 15, 1961, pp. 97-122. W o o s t e r , W. S., I 9 6 O : " P r e l i m i n a r y R e p o r t S t e p I E x p e d i t i o n " . . P a r t I , P h y s i c a l and C h e m i c a l D a t a . S c r i p p s I n s t i t u t i o n of O c e a n o g r a p h y R e f e r e n c e 61-9, J a n u a r y 16, I 96 I . W y r t k i , K., I963: "The H o r i z o n t a l and V e r t i c a l F i e l d of . M o t i o n i n . t h e P e r u C u r r e n t " . B u l l . S c r i p p s I n s t i t u t i o n of O c e a n o g r a p h y . 8, 3 '3~346. APPEND I X 36 I t h i n k t h a t t h e p r e s e n t s t u d y of some f e a t u r e s of the n o r t h e r n C h i l e a n w a t e r s , t h r o u g h t h e a n a l y s i s of t h e M a r c h i l e II E x p e d i t i o n d a t a , s u g g e s t s t h a t t h e r e a r e a few i m p r o v e m e n t s to be i n t r o d u c e d i n f u t u r e s t u d i e s i n t h e same a r e a . In t h e f i r s t p l a c e t h e d i r e c t c u r r e n t m e a s u r e m e n t s , u s i n g p a r a c h u t e d r o g u e s , s h o u l d be e x t e n d e d t o t h o s e a r e a s i n w h i c h t h e e d d i e s were f o u n d . T h i s w i l l g i v e a b e t t e r u n d e r s t a n d i n g of t h e c o m p l i c a t e d c u r r e n t p a t t e r n i n t h i s a r e a and i t w i l l a l s o g i v e an i d e a of how permanent t h e d e s c r i b e d f e a t u r e s a r e . I s u g g e s t t o do t h e s e m e a surements m a i n l y i n P r o f i l e 2, where t h e l a r g e eddy was f o u n d . I s u g g e s t a l s o i m p r o v i n g t h e c r u i s e p l a n , so as t o g e t i n t e r m e d i a t e v a l u e s of t h e p r o p e r t i e s , t o make the i n t e r p o l a t i more r e I i a b I e . As u p w e l i i n g i s an o u t s t a n d i n g f e a t u r e ^ t o i n c l u d e n u t r i e n t s i n the o b s e r v a t i o n s w o u l d c e r t a i n l y g i v e a much b e t t e r i d e a of i t s i n t e n s i t y and e x t e n t , e s p e c i a l l y i n t h e coas t a I r e g i o n . As t h e r e a r e some i n d i c a t i o n s t h a t t h e p r e s e n c e of i n t e r n a l waves m i g h t i n f l u e n c e t h e c u r r e n t s n e a r t h e c o a s t , i t w o u l d be v e r y i n t e r e s t i n g to r e p e a t s y s t e m a t i c a l l y one or two of t h e p r o f i l e s ( P r o f i l e 2, f o r e x a m p l e ) and s e e i f th i s i s s o . 37 A w e l l d e s i g n e d a n c h o r e d buoy i n t h i s a r e a w o u l d a l s o g i v e a v e r y v a l u a b l e i n f o r m a t i o n , as f a r as p e r i o d i c a l and o t h e r p r o p e r t i e s are c o n c e r n e d . A f u r t h e r i m p rovement i n p a r a c h u t e d r o g u e m easurements wou l d i n c l u d e t h e use of s i m p l e r a d i o t r a n s m i t t e r s a t t a c h e d t o the d r o g u e s t o p e r m i t t h e i r d e t e c t i o n from s i m p l e s t a t i o n s on l a n d . The wind o b s e r v a t i o n s c o u l d a l s o be i m p r o v e d , b e c a u s e t h e s u r f a c e c u r r e n t s a r e so l a r g e l y d e p e n d e n t on the w i n d . T h e r e i s no d o u b t t h a t t h i s a r e a i s v e r y i n t e r e s t i n g f o r b i o l o g i s t s , due t o t h e f e a t u r e s a l r e a d y d e s c r i b e d . Now do t h e s e f e a t u r e s o c c u r i n o t h e r s e a s o n s of the y e a r and i n what e x t e n t ? The answer c o u l d be o b t a i n e d o n l y w i t h a w e l l d e s i g n e d p l a n of o b s e r v a t i o n s . P o s s i b l y the i n f o r m a t i o n o b t a i n e d f r o m an a n c h o r e d buoy w o u l d be of f u n d a m e n t a l i m p o r t a n c e . 38 2 4 ' 2 6 " 74« 7?" P R O F I L E 1 J O P R O F I L E 2 .11 P R O F I L E 3 . 3 0 P R O F I L E 4 .31 P R O F I L E 5 .51 . 5 2 . 5 3 . 5 4 FIO 2 B ATHYT HER MOOR APHIC STATIONS y__ <i . 5 9 <? . 6 0 .61 S A N F E L I X I.* 6 . 2 S A N A M B R O S I O I 7 0 ' W E3 - 4 A R I C A N ' l . . . . . 2 0 IP M A D R I D - 2 1 P P I C H A L O l . . . 41 " j l Q U I Q U E trz P P A T A O H E l 2 0 ° 2 2 * ) A N T O F A -G A S T A ! 2 4 * 26° F I G . I S T A T I O N C H A R T M A R C H I L E II E X P E D I T I O N IN J U L Y 1 9 6 2 . ( I N S E T ' F I G . 2 . ) 39 14-0 8 0° 70° 80° 70° a 2C \] S Arte a If 1 ffogas-4|[; to o 20 o 3C August and September $t i May, June and July 1 1 I J v i p o . o 30 80° 70° eo° 70° FIG.4. WINDS DURING WILLIAM SCORESBY EXPEDITION IN 1931. F IG . 5 . WINDS DURING M A R C H I L E II E X P E D I T I O N . 1+2 F I G . 6 . D Y N A M I C T O P O G R A P H Y O F T H E S U R F A C E O F T H E S E A W I T H R E S P E C T T O T H E I O O O d b . S U R F A C E . ( A n o m a l i e s in D y n a m i c M e t e r s . ) F I G 8 D Y N A M I C T O P O G R A P H Y A T T H E O C P T H O F 1 0 0 m I l O O O A l F I C II C U R R E N T S O F F A R I C A • I O n , O . J K n o l l , 1 0 0 m , 0 S K n o t , , 2 S 0 « , 0 . 4 K n o t . n u t . cwmitim err M n » m ' io«,»iifc*ti no* », OJIMN. k9 I9«-20»-2I. F I G . 14 . N E T O F S T A T I O N S F O R G E O S T R O P H I C T R A N S P O R T 51 N O R T H E R N PRO F I L E * — H O O O d b S O U T H E R N P R O F I L E F l S. 15. G E O S T R O P H I C T R A N S P O R T IN S V E R O R U R 52 7 2 « 7 1 * 7 0 * F I G . 16. D I S T R I B U T I O N O F S U R F A C E T E M P E R A T U R E IN * C 53 F I G 17 Dlttribution of Tompuraturo ( * C ) in P r o f l l t 4 , I 8 ' I 9 o f J u l y , 1 9 6 2 100 9 0 SO 70 6 0 SO 4 0 30 20 10 0 M i l t i F i e IS . D i s t r i b u t i o n of T o m p o r a t u r o CC) In P ro t l l o 3 , 16-18 J u l y , 1962. 5k F I S . 19. D l a t r l b v t l o n o f T t m p a r o t a r t <"C) In P r o f i l a 8 , 8 6 - 2 6 Ju ly , I M 2 . 55 F I G . 2 0 . D I S T R I B U T I O N OF T E M P E R A T U R E C C l . A T T H E O E P T H O F 100m. 56 57 58 59 72« 60 F I G . 2 5 D I S T R I B U T I O N O F S A LI NI T Y (%«) A T T H E D E P T H O F l O O m I * •  61 F I G ? 6 D I S T R I B U T I O N O F S A L I N l T Y <%.) A T T H E O E P T H O F 2 5 0 m 63 9 0 SO TO 6 0 50 4 0 30 2 0 10 0 fcUloo F i o 2 8 D i s t r i b u t i o n o l S a l i n i t y O J in Pro tin l , 1 2 - 1 4 J u l y , 1962 . 100 9 0 SO 7 0 6 0 3 0 4 0 SO 2 0 10 O M l l o t F 1 0 . 2 9 . D i s t r i b u t i o n o l Salinity ( X J In P r o l i l t 5 , 2 5 - 2 6 J o l y , 1962 Sk F I O 3 0 O l a t r l b a t l o n of Salinity (%J kl P r o t i l t 3 , 16-18 J u l y , 1962. 65 F I G . 31 . D I S T R I B U T I O N O F O X Y G E N C O N T E N T ( m l / l ) A T T H E S U R F A C E . 66 8. S3. Ol itr l ftgi loa e l Oaigtn Oaattat (rnlrQ la Pro l i l t S, U - M Mf, 67 F I G . 34 . D I S T R I B U T I O N O F O X Y G E N C O N T E N T ( m l / l ) , A T T H E D E P T H OF 9 0 m . 68 fiese D l i t r laa l lon o» Oi»«.n C o n K n l (ml/l) In P r o t l l t 8, 18-18 J a i l , 1982. F I G . 3 6 . D I S T R I B U T I O N OF O X Y G E N C O N T E N T (ml/l), AT T H E D E P T H O F 1 0 0 m . 70 71 72 72* 7}» 70» r I 0 . 3 9 . D E P T H S O P M I X E O L A Y E R ( m ) . 73 F I G . 4 2 . T H E W A T E R M A S S E S 75 76 F I S 4 4 O U t r l B n t l o r i o l T t m p t r o l o r * C O I" P r a l l l t 6 , 2 6 - 2 9 J u l y , 1962 800 480 4 0 0 380 300 290 200 ISO 100 SO O " l i t « •10 . 4B. • t . t r l i a t i M of AM * " re f l la 6, M * M i»tt, W t . 77 no. 4 8 . O l i t r l o a l l o n o f <>••«•• C o o H a f In P r o f Ho 6, 28-i» J o l t , 1*81. 

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