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Lunar tides in the E-region Kennelly-Heaviside layer Niblock, Peter A. 1952

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ns > /?; NJT Lar LUNAR T I D E S IN THE E-REGION / KENNELLY-HEAVISIDE LAYER PETER A. NIBLOCK A THESIS SUBMITTED IN PARTIAL FULFILMENT OP THE REQUIREMENTS FOE THE DEGREE ©F MASTER OF APPLIED SCIENCE i n the Department of E l e c t r i c a l E n g i n e e r i a g We accept t h i s t h e s i s as conforming to the standard r e q u i r e d from candidates f o r the degree of MASTER OF APPLIED SCIENCE THE UNIVERSITY. OF BRITISH COLUMBIA A p r i l , 1952 ABSTRACT A number of Investigators have conducted research on the earth's atmosphere. Among them have been Laplace, Lord Kelvin and Simpson, who were interested, primarily, i n pressure variations i n the atmosphere; Pekeris and Q-. I. Taylor, who were Interested i n the mechanism of atmospheric resonances; and Balfour-Stewart, Chapman, and Appleton and We eke a, who were interested In upper-atmosphere researoh. However, a l l these investigators had one Idea In common; they sought to establish the presence of lunar and solar effects upon the earth 1s atmosphere. Even after the work which has been done on lunar tides i n the E-region of the Kennelly-Heavlslde layer by Appleton and Weekea and other investigators, there are s t i l l questions which remain unanswered on this subject. A description i s given of an investigation performed at The University of B r i t i s h Columbia to determine the magni-tude of a lunar tide i n the S-reglon of the Kennelly-Heavlslde layer. Details are Included of design considerations f o r a pulse-type communications receiver to operate i n the 0*5 to 30 mc/s. band. The main differences between the unit discussed and a standard communications receiver l i e i n the band-pass, or selectivity characteristics and i n the receiver recovery time after shock excitation by very strong radio frequency fields . I II Also included are details of the transmitting units, the antenna, and the calibration display unit used i n the Investigation, Analysis of the data gathered during the investiga-tion shoved that there was no tide i n the Kennelly-Heavislde layer Region-E of the magnitude or phase of that found by Appleton and Weekes i n 1939. An analysis of the data gathered for the lunar tides Investigations produces strong evidence of daytime D-layer ionization between heights of 50 and 85 kilometers. This evi-dence i s discussed and fi e l d s for future researoh are suggested. Comparisons are made between the results of Chapman's analysis of the lunar pressure oscillations at ground level and the accumulated data from the ionospheric lunar tide inves-tigation of Appleton and Weekes and those from this investiga-tion. The data derived from these widely differing sources are shown to be completely compatible. TABLE OF CONTENTS Page ABSTRACT I I INTRODUCTION 1 I I THE EXPERIMENTAL EQUIPMENT 5 l a The Ionospheric Receiver 5 l b C i r c u i t Analysis f o r Ionsopheric Receiver .. 8* 2. The Ionospheric Pulse Transmitter 17 3. t h e Antenna 19 K. The Timing and Presentation Units 22 I I I OBERVATIONS 2k IV RESULTS OF THE INVESTIGATION 26 V DISCUSSION 31 VI CONCLUSIONS 35 ACKNOWLEDGEMENTS 37 LITERATURE CITED 38" BIBLIOGRAPHY kl APPENDIX Table I E-layer Height Mi-Table I I Deviations from Solar Control Curve . 45 Table I I I Deviations from Solar Control Curve arranged by lunar time 46 LIST OP ILLUSTRATIONS Pftge Figure l a - Ionosphere Building and Mast The University of B r i t i s h Columbia 6 l b - Ionospheric Sounding Equipment . 6 l c - Block diagram of the Ionospheric Sounding Unit 7 2 - Representation of a Loaded, Double-tuned, Mutually-coupled I. P. Transformer 10 3 - Automatic Gain Control C i r c u i t i n I. P. Amplifier-stage of the Receiver • .- 10 4 - Receiver Gating C i r c u i t 14 5 - Stepped Attenuator Control f o r Pulse Communications-receiver .. .. 14 5& - Ionospheric Pulse-type Communications Receiver .. l6 6 - Ionospheric Transmitter . 18 7 - The Crossed-delta Antenna . 18* 8 - Propagation at V e r t i c a l Incidence 21 9 - The Marker Generator Unit 21 10 - D-layer Echoes showing siz e r e l a t i v e to E-echo es 28 11 - E-layer Echoes on 200 km. Presentation ..... 28 12 - Map showing Lunar Atmospheric Pressure O s c i l l a t i o n s at Various Observatories. (Extracted from the Proceedings Royal Society . of London A, v o l . 151, p. 110 J 777777777777 34 GRAPHS Number Solar Control Graph f o r 14 days ending J u l y 28, 1951 I Solar Control Graph f o r 14 days ending August 11, 1951 I I Number Running Averages f o r 14 days ending J u l y 28, 1951 . I l l Running Averages f o r 14 days ending August 11, 1951 IV E - l a y e r Height f o r August 11^ 1951, showing noon-hour r e t a r d a t i o n V I INTRODUCTION From the middle of the nineteenth century, a great deal of i n t e r e s t has been displayed by various investigators i n the behaviour of the atmosphere. In the f i r s t atmospheric investigations, barometric pressure data were analyzed f o r solar, d i u r n a l and semi-diurnal components, and l a t e r f o r lunar components. Next, a c o r r e l a -t i o n was sought between the barometric o s c i l l a t i o n s and v a r i a -tions i n the earth's magnetic f i e l d . This changed the place f o r i n v e s t i g a t i o n from ground l e v e l to the upper atmosphere. Having started to investigate the upper atmosphere by magnetic means, i t was quite l o g i c a l that investigators should continue by using radio sounding methods. Towards the close of the nineteenth century, S i r William Thomson^, a f t e r an i n v e s t i g a t i o n of the d a l l y pressure variations i n the atmosphere, suggested that the semi-diurnal t i d e which Laplace had a t t r i b u t e d to thermal e f f e c t s was, i n 1. 2 reality, due to gravitational causes. Lord Kelvin( 2), subse-quently, suggested that an atmospheric resonance with a period of 12 hours would account for the gravitational force, which has a diurnal period, producing pressure variations with a semi-diurnal period. In 1918, Simpson(j), examining the data then av a i l -able, found a solar barometric pressure o s c i l l a t i o n and gave the magnitude of this tide as p z = 0 . 3 5 7 5 / n 3 e Snn (*Lt r /S+°) where p » atmospheric pressure i n mm. of mercury 0 = co-latitude 0 s longitude t = local time Laplace^), i n one of his many experiments, tried unsuccessfully to find a lunar barometric pressure oscillation. It was not u n t i l 1935 that this tide was measured. In that year, Chapman^) described a lunar semi-diurnal pressure osc i l l a t i o n with an amplitude l / l 6 that of the solar wave and with a phase of 7 0 0 . This he found from an analysis of the barometric records from many observatories around the world. It was essential that a very large volume of data be analysed to segregate such a small component from the large number of other variations present i n the observatories 1 records. 3. In 1929, G. I* T a y l o r ^ found evidence of a free atmospheric resonance with a period of 1 0 | hours i n data which was gathered during the Krakatau eruption of I883 and during the explosion of the Great Siberian Meteor. However, a resonance with a period such as this i s totally unsuited to adaption to the theory that the barometric oscillations are due to an atmospheric resonance, for to produce the required amplification of the tides, such a resonance would require a free period of 12 hours minutes. As a solution to this apparent contradiction, Pekeris has proposed that a special temperature distribution must exist i n the upper atmosphere whioh w i l l sustain two different periods of free oscillation. The salient point of this d i s t r i -bution i s that there i s a discontinuity i n the temperature distribution i n the upper atmosphere and, as a result of this, a free os c i l l a t i o n of lD^ and another of 12 hours may exist simultaneously i n the atmosphere. A l l the investigators cited were concerned, primarily, with atmospheric oscillations and variations at ground level. However, these oscillations have been shown to exist i n the upper atmosphere also. In 187*5, Balfour-Stewart(g) stipulated that the quiet-day magnetic variations were due to horizontal convective motions of the upper atmosphere across the earth's magnetic f i e l d * these motions being due to atmospheric o s c i l l a -tions. 4. The r a t i o of the lunar to solar component of the magnetic v a r i a t i o n has been shown to vary from 10 at sunspot maximum to 7»5 a<& sun spot minimum, whereas the v a r i a t i o n i n the r a t i o of the lunar to s o l a r component of the pressure o s c i l l a t i o n has an average value of about l 6 f o r the whole world, with values as high as 28 being recorded i n southern England. The difference between these two parameters and t h e i r v a r i a t i o n with geographic l o c a t i o n has given r i s e to the b e l i e f that the currents causing the solar magnetic v a r i a -t i o n and those causing the lunar magnetic v a r i a t i o n do not flow at the same a l t i t u d e . I t i s further thought that the r e l a t i v e pressure o s c i l l a t i o n s vary with a l t i t u d e ^ . In view of the v a r i a t i o n experienced i n the r a t i o of the s o l a r to lunar barometric t i d a l component i n d i f f e r e n t parts of the world, i t was proposed to perform an experiment s i m i l a r to that performed by Appleton and Weexes( 1 0) to ascer-t a i n i f the var i a t i o n s noted i n barometric o s c i l l a t i o n s were to be found i n the ionospheric o s c i l l a t i o n s . 5 I I THE EXPERIMENTAL EQUIPMENT The equipment used In t h i s i n v e s t i g a t i o n was patterned a f t e r that used by B r e i t and Tuve In t h e i r pulse retardation method of ionospheric height measurement^!). The equipment i s divided into four sections f o r t h i s d escription! the communications-type radio receiver designed s p e c i f i c a l l y f o r pulse-reception; the ionospheric pulse-trans-mitter, the crossed-delta-antenna, and the timing and presenta-t i o n u n i t on which data were displayed and i n which the timing markers necessary f o r height c a l i b r a t i o n were generated. The equipment i s shown i n block form i n Figure l c . A 75 kc/s. quartz c r y s t a l - c l o c k i n the timing u n i t i s used to t r i g g e r b l o c k i n g - o s c i l l a t o r s which produce height c a l i b r a -tion-markers on the display cathode-ray tube. In addition to t h i s function, the b l o c k i n g - o s c i l l a t o r s generate the pulses which are fed as t r i g g e r s to the "scale of four 1* counter u n i t . The "scale of four" then generates the time base d e f l e c t i o n voltages f o r the cathode ray tube display, the transmitter trigger-pulse and the receiver gating-pulses. l a . The Ionospheric Receiver A suitable receiver f o r accurate ionospheric measure-ments must have c e r t a i n q u a l i t i e s which are not common to standard communication units. These q u a l i t i e s are: P i g . l a Ionosphere B u i l d i n g and mast The U n i v e r s i t y of B r i t i s h Columbia P i g . l b Ionospheric Sounding Equipment P ft ni (ft S c f l J . f i OF . rout. COUNTER. U a J ft 75 kc/s. C t O C K "1 /'50xc/s HeiG.nr rimmed 3 T BoarHP CMH60£ fOLLOVttrX MooutmoR T. p. >»r 4lc^a Sac. .HtCKTSuppij l a w vo/fogfisufp / j R&GUUfftD tf/d// VOirRGE SUPPLY Jkv. 1 — a ->• > and Pefkcfion/lmp/i/kf Otlfptft So*v 0 0 PULS£TYP£ ConnuMwioNs Sating Control &(ock diagram of the Tonosphenc Sounding Unit g Ca) adequate signal to noise ratio for the detection of weak r.f. pulse packages (hereafter called pulses), (b) adequate bandwidth to reproduce the received pulse without undue distortion, (c) a rapid recovery time after complete overload (this should not be greater than 5° micro-seconds), (d) a calibrated attenuation system for comparing the relative amplitude of different echoes. The general procedure used i n designing such a receiver i s outlined i n the following sections. lb. Circuit Analysis for Ionospheric Receiver The necessary bandwidth for the I. F, amplifiers may be obtained by using stagger tuning methods, by using low Q coupled circuits at low frequency, or by using higher Q high frequency circuits. The second method was adopted because of the ease with which such circu i t s could be aligned. The minimum bandwidth for pulse-receivers i s dictated by the length of the transmitted pulse. A 5° micro-second radio f r e -quency pulse was chosen for transmission after striking a compromise between the dictates of adequate.echo resolution power i n the display equipment and gain-bandwidth-factor and slgnal-to-noise ratio considerations i n the receiver. From the Inverse pulse length expression for a 50 micro-second pulse, the minimum permissible receiver bandwidth i s 20 kc/s. This bandwidth could be increased for improved 5. echo r e s o l u t i o n and reduced rece iver time delay , but f o r maxi-mum rece iver operating s igna l - to -no i se r a t i o , the bandwidth should be such that the durat ion of received noise impulses and rece ived s i g n a l impulses are the same. Because t h i s equip-ment was designed to operate on frequencies occupied s imul ta-neously by other commercial rad io equipment not of a true pulse nature, ( i . e. , commercial continuous-wave and r a d i o -phone s tat ions) the minimum bandwidth compatible wi th pulse r e s o l u t i o n should be used, as interference from these s ta t ions has proven, i n previous experiments, to be a major problem. The value of K, the coupl ing c o e f f i c i e n t i n a c r i t i c a l l y - c o u p l e d doubled-tuned c i r c u i t f o r a given band-width and where "Q" primary i s equal to "Q" secondary i s ( i g ) ; K . * where K c t*= c o e f f i c i e n t of coupl ing at c r i t i c a l coupl ing M = A c t u a l output ^ /2 cyc les o f f resonance Output voltage at resonance N - number of stages assumed a l l a l i k e f 0 = resonant frequency The value of Qp and Q s to produce c r i t i c a l coupl ing i n a double tuned coupled c i r c u i t i s I Where K c i s as defined above and Qp and Q,s are the q u a l i t y f a c t o r s of the primary and secondary windings of the t r a n s -former. 10. PRESENTATION OF k LORDED, DOU»l£ TUNED, riUTUFILLI COUPLED I. F. a.ri eeas 25 i ^ / c / -flUTOrlRTlC GrWTcOHTR0L CIRCUIT IN I F . fltlPUFIER STAGE OF THE R£.CEIVLfZ o-2S n l l * ': When Qp and Q 8 are equal , and t h i s Is so i n the ease which i s p r e s e n t l y of i n t e r e s t , then Consider now the secondary c i r c u i t of t h i s t r a n s f o r -mer. The Q, o f t h i s c i r c u i t must be adjusted to a s p e c i f i c value which i s dependent on the c o u p l i n g of the two c o i l s of the transformer. I n general , the Q, of the transformer second-a r y i s i n i t i a l l y very h i g h , but i t may be reduced by s e r i e s o r p a r a l l e l - r e s i s t a n c e l o a d i n g . Because of i t s s i m p l i c i t y , the p a r a l l e l - r e s i s t a n c e l o a d i n g method was used. The s i z e of the p a r a l l e l l o a d i n g - r e s i s t a n c e may be d e r i v e d as f o l l o w s ! I n an a n t i - r e s o n a n t c i r c u i t (see P i g . 2) where ? s = the impedance l o o k i n g i n t o the two t e r m i n a l n e t -works before R^ i s added to the c i r c u i t . ft1 = the unload q u a l i t y - f a c t o r of the inductance L f l i s as p r e v i o u s l y def ined. When t h i s c i r c u i t i s shunted by the r e s i s t a n c e R^, the modified value of Z Q becomes 7 = (**){*<.) _ Q'uLsJe'i. The c o n d i t i o n that Q s - i - m ^ s t a l s o be s a t i s f i e d , that is? *C Q'IO LS -+- RU 12, whence, a f t e r s i m p l i f i c a t i o n , - 1 — — — — . . S*sS I F o r l a r g e values of Q, 1, to -^From these expressions, I t was determined that three stages of intermediate frequency a m p l i f i c a t i o n , u s i n g 6BA6 miniature remote-cutoff pentodes preceded hy a mixer and two stages of R, F . a m p l i f i c a t i o n , should produce an output of l i v o l t s w i t h 4 m i c r o - v o l t i n p u t . The R. F . t u r r e t i n the r e c e i v e r i s a standard assembly manufactured by the Canadian Marconi Company. The use of t h i s u n i t d i c t a t e d that the I. F. should be 575 k c / s . The recovery-time of a r e c e i v e r designed f o r pulse s e r v i c e must be very short. To ensure t h i s , R. C. c o u p l i n g networks were placed i n the g r i d - c i r c u i t s of the R. F . and I. F . a m p l i f i e r s (see F i g . 3 ) . These c i r c u i t s overload v e r y e a s i l y , but t h e i r time constant i s 10 micro-seconds and thus^ they recover very r a p i d l y a f t e r the passage of a l a r g e p u l s e . T h e i r p r i n c i p l e of operation i s that during the p e r i o d of a l a r g e p u l s e , the c o n t r o l - g r i d o f the stage i s d r i v e n i n t o the current r e g i o n . This current develops a b i a s a c r o s s Rg, reduc-i n g the tube gm to such an extent that more s e r i o u s o v e r l o a d i n g does not occur i n the higher l e v e l stages. I n t h i s i n v e s t i g a t i o n , i t was necessary to introduce i d e n t i f i c a t i o n markers i n t o the d i s p l a y and to provide f o r b l a n k i n g the r e c e i v e r during the p e r i o d s when the markers were being d i s p l a y e d to prevent masking o f these markers by < s i g n a l s coming through the r e c e i v e r . The b l a n k i n g pulse i s Introduced i n t o the s u p p r e s s o r - g r i d s o f the f i r s t and second I . F. a m p l i f i e r s (see F i g . 4). To accommodate the very l a r g e range of s i g n a l s experienced i n i o n o s p h e r i c i n v e s t i g a t i o n s , a stepped attenuator was b u i l t i n t o the r e c e i v e r . T h i s i s a modified form of R. F . and I . F. g a i n c o n t r o l , g i v i n g 1 2 0 d b f s of a t t e n u a t i o n I n 6 db steps (see F i g . 5)» The b a s i c design procedure f o r t h i s com-ponent was as f o l l o w s ! From the t r a n s f e r c h a r a c t e r i s t i c curves f o r the tube used i n the c o n t r o l l e d c i r c u i t , the value of the g r i d b i a s voltage E e c was determined f o r where m == number of i d e n t i c a l stages being c o n t r o l l e d . n i 1 , 2 , 3, 4, 5, e t c . *• the attenuator s e t t i n g gm s tube transconductance f o r a t t e n u a t o r s e t t i n g n gmo tube transconductance f o r attenuator s e t t i n g 0 From an a n a l y s i s of the C i r c u i t of F i g . 5, i t i s apparent that R^ f o r attenuator s e t t i n g n i s GATING, R J L S E S rt?on SCALE OF FOUR UN IT R EC E I V ER GiRTllHG ClRCU IT. .1 1 a-ot = +/OSY. /~7&. 5. 1 -'-SUIT*-=L o-o/ @n fiiC STEPPED ^TTENuBron. CONTROL 4 FOR. PULSE COMMUNICATIONS— . /?S ^ "^g £g /^O 15. where s t o t a l a t t e n u a t o r c o n t r o l r e s i s t a n c e f o r step n R = chosen value of voltage dropping r e s i s t o r E y.,. s b i a s supply voltage (regulated) I = cathode, current f o r one stage w i t h E k n v o l t s g r i d b i a s a p p l i e d to that stage. From a p l o t of t h i s f u n c t i o n , the incremental values of r e s i s t a n c e necessary per attenuator step can be determined. The o r i g i n a l CSR^A t u r r e t used I n the r e c e i v e r d i d not cover the frequencies between 5°0 k c / s . and 1|?00 k c / s . However, a set of c o i l s was provided f o r frequencies between 80 and 200 k c / s . These were removed and those f o r the 500 to 1500 k c / s . range were designed and s u b s t i t u t e d . The design procedure was to e s t a b l i s h the c o r r e c t tuning range r a t i o f o r the L . F . o s c i l l a t o r by the c a l c u l a t i o n of a s u i t a b l e s i z e f o r the o s c i l l a t o r padding condenser, and then to choose an inductance to make the L . F . o s c i l l a t o r operate between the c o r r e c t frequencies. F i n a l l y , the R. F . a m p l i f i e r a n t i - r e s o n a n t c i r c u i t s parameters were c a l c u l a t e d to provide two-point t r a c k i n g w i t h i n the r e q u i r e d frequency range. Tests on t h i s r e c e i v e r have shown that the e s s e n t i a l c h a r a c t e r i s t i c s are as f o l l o w s ; (a) bandwidth 21 k c / s . at 3 db down, (b) r e c e i v e r recovery time a f t e r decay of t r a n s m i t t e r pulse i s such that pulses r e f l e c t e d f r o m a n i o n i z e d l a y e r a t 30 km. w i l l not be attenuated, F i g . 5a Ionospheric Pulse-type Communications Receiver (c) the r e c e i v e r s e n s i t i v i t y Is b e t t e r than 1 m i c r o - v o l t at a l l frequencies f o r a 6 db signal-to<*noise r a t i o , (d) the r e c e i v e r does not d r i f t more than 2 k c / s . from a c o l d s t a r t and t h i s d r i f t occurs during the f i r s t 15 minutes of r e c e i v e r o p e r a t i o n , a f t e r which there i s no f u r t h e r a p p r e c i a b l e d r i f t , (e) the tuning range of 200 k c / s . to 30 mc/s. r e q u i r e s that the r e c e i v e r be tuned through i t s intermediate frequency of 575 k c / s . T h i s may be done without i n s t a b i l i t y a t the I . P. channel frequency. To o b t a i n the d e s i r e d degree of s t a b i l i t y at the 1. P. frequency, a d d i t i o n a l L , C. decoupling networks had to be i n c l u d e d i n the cathode c i r c u i t of the R. P. and I . P. a m p l i -f i e r s and a d d i t i o n a l H. T. decoupling had to be used i n a l l stages. I n a d d i t i o n , a n t i - r e s o n a n t t r a p s had to be I n s e r t e d i n the R. P. a m p l i f i e r and mixer c i r c u i t s to smooth out a, l a r g e i n c r e a s e i n r e c e i v e r g a i n which occurred a t the I . P. channel frequency. 2. The Ionospheric Pulse Transmitter The t r a n s m i t t e r ( F i g . 6) used i n the i n v e s t i g a t i o n was designed by the s t a f f of the Radio Physics Laboratory of the Defence Research Board, Department of N a t i o n a l Defence, and was modified by the author w h i l e he was employed there. The t r a n s m i t t e r now produces 5 ° micro-second R. P. p u l s e s w i t h a r e p e t i t i o n r a t e which i s v a r i a b l e to 200 pulses per second. The f i n a l a m p l i f i e r , which i s an a p e r i o d i c p u s h - p u l l F i g . 6 Ionospheric Transmitter £ , 7 . THE C R O S S E D - D E L T W / 2 - / O O O -TL. rJorJ-Z NbUCTiVE ; i r 19, C l a s s - B - l i n e a r u n i t , develops a peak pulsed power of 15 kw. and i s d r i v e n by a 3 kw. v a r i a b l e frequency p u s h - p u l l C o l p l t t s o s c i l l a t o r . The tuning range of t h i s t r a n s m i t t e r was i n a d e -quate f o r the needs of the i n v e s t i g a t i o n and i t was, t h e r e f o r e , modified to cover the c o r r e c t frequencies . The modified f i n a l a m p l i f i e r operates w i t h a designed p l a t e - t o - p l a t e l o a d of 600 ohms, which i s s u i t a b l y matched by the r a d i a t i o n r e s i s t a n c e of the v e r t i c a l t r a n s m i t t i n g antenna* The t r i g g e r pulse from the "scale of f o u r " a m p l i f i e r i s f e d to a t h y r a t r o n gate on a s y n t h e t i c delay l i n e . The discharge of t h i s l i n e actuates a b o o t s t r a p c a t h o d e - f o l l o w e r ^ and t h i s screen-rmodulates the 3 kw, 3E29 pulsed o s c i l l a t o r . T h i s o s c i l l a t o r , as mentioned before, d r i v e s the p u s h - p u l l 715B*s i n the a p e r i o d i c C l a s s - B - l l n e a r f i n a l a m p l i f i e r . 3* The Antenna Antennas w i t h strong v e r t i c a l d i r e c t i v i t y are d e s i r -able f o r v e r t i c a l incidence i o n o s p h e r i c sounding. Power r a d i a t e d by an antenna at o b l i q u e incidence may l e a d to e r r o -neous r e s u l t s , i f i t i s r e f l e c t e d back to the r e c e i v e r from the ionosphere, or from surrounding l a n d masses. I n the f i r s t case, ionosphere height readings w i l l be produced which d i f f e r from the v e r t i c a l height of the i o n o s p h e r i c l a y e r by a f a c t o r which approaches the cosecant of the angle of r a d i a t i o n (see F i g . 7). I n "ft16 second case, l a n d masses may produce unwanted echoes having many of the e s s e n t i a l c h a r a c t e r i s t i c s of i o n o s -p h e r i c echoes. 20. The s i t u a t i o n i s f u r t h e r complicated because i o n o s -p h e r i c sounding g e n e r a l l y r e q u i r e s readings to be made over a l a r g e band of frequencies. T h i s means that a s u i t a b l e antenna, i n a d d i t i o n to having good v e r t i c a l d i r e c t i v i t y , must be a p e r i o d i c . These requirements r e s t r i c t the choice of antenna to those of the t r a v e l l i n g wave group. Mr. J . W. Gox^ij.j, now of Defence Research Board, Department of N a t i o n a l Defence, Ottawa, has done extensive work on t h i s subject and has c o n t r i b u t e d to the development of an antenna which i s p a r t i c u l a r l y w e l l s u i t e d to Ionospheric sounding. I t i s the v e r t i c a l del ta-antenna. E l e c t r i c a l l y , i t i s equivalent to a v e r t i c a l rhombic w i t h the lower h a l f o f the rhombic being c o n t r i b u t e d by the g r o u n d - r e f l e c t e d image of the antenna. The low frequency c u t - o f f o f the antenna i s a f u n c -t i o n of the area enclosed by the d e l t a and i s lower f o r d e l t a s o f g r e a t e r a r e a . The antenna used during the experiment has a height of 85 f e e t and a base l e n g t h of 180 f e e t . This has proved to be a s a t i s f a c t o r y r a d i a t o r f o r frequencies as low as 600 k c / s , although the l o a d presented to the f i n a l a m p l i -f i e r s at t h i s frequency has a l a r g e r e a c t i v e component. The r e c e i v i n g antenna i s i d e n t i c a l to the t r a n s m i t t i n g one and i s erected a x i a l l y w i t h i t , but w i t h the planes of the two antenna mutually at r i g h t angles. t < i e i ° ! '«i • tk — N O R M A L "0- flng/e o p r aciioHon F i g . 9 The Marker Generator U n i t 22. The major lobe of r a d i a t i o n of the antenna Is v e r -t i c a l and there are minor lobes between 0° and 60° which a r e a f u n c t i o n of the frequency. The low angle lobes a r e small and are not of great Importance. 4 . The Timing and P r e s e n t a t i o n U n i t s The free space propagation v e l o c i t y of r a d i o f r e -quency electro-magnetic o s c i l l a t i o n s i s 3 x 10 m/s. This Is equivalent to one ki lometer every 3-1/3 micro-seconds. However, i n i o n o s p h e r i c sounding, the energy must pass to the r e f l e c t i n g l a y e r and r e t u r n to the t r a n s m i t t e r (see P i g . 7). Thus, f o r a l a y e r height of A kms., the time r e q u i r e d f o r a pulse to t r a v e l from the t r a n s m i t t e r to the l a y e r and back to the r e c e i v e r would be T a 2(3*1/3) A m i c r o -seconds. I f one-kilometer c a l i b r a t i o n markers were r e q u i r e d , these would have to be 6-2/3 micro-seconds a p a r t . I n the equipment, the markers are generated by a 75 k c / s , c r y s t a l o s c i l l a t o r whose second harmonic i s used to produce the markers. B l o c k i n g o s c i l l a t o r s generate d i s t i n c t i v e 10, 50, and 200 km. markers. These markers, together w i t h the output Of the i o n o s p h e r i c r e c e i v e r , a r e d i s p l a y e d on a cathode-ray tube. The marker generator u n i t and d i s p l a y u n i t a r e shown i n Figure 8. 23* The d i s p l a y i s such that i t i s p o s s i b l e to read l a y e r heights to h a l f a k i l o m e t e r and to check the time p o s i -t i o n of the transmitted pulse to the same accuracy. Thus, the l a y e r height may be determined as a d i f f e r e n c e between two time readings which minimizes a l l constant value height e r r o r s . A reading v/as taken on a f i r s t and m u l t i p l e r e f l e c t i o n and the heights were found to be 120 kms. and 24-1 kms. These readings were taken under f a r from i d e a l c o n d i t i o n s , since at the time the check was made, the echoes were weak and l o c a l radio noise was high. T h i s would account f o r the 1 km. height discrepancy between the s i n g l e and m u l t i p l e echo. 24. I l l OBSERVATIONS Measurements were taken every 15 minutes between 0800 and 1600 hours, l o c a l standard time, f o r a 30-day p e r i o d . The l a y e r heights were measured to an accuracy of 0.5 km. a t a constant frequency of 2 mc/s. During the p e r i o d In which readings were taken, t h i s frequency was w e l l below the E - l a y e r c r i t i c a l frequency. D a i l y height v a r i a t i o n s of 5 to 7 kms. were recorded, but these were due to s o l a r i n f l u e n c e s . I n a d d i t i o n to these r e g u l a r v a r i a t i o n s , others of 2 to 3 kms. i n one h a l f hour occurred at random i n t e r v a l s d u r i n g the 30-day p e r i o d . These are thought to be true v a r i a t i o n s i n l a y e r height and t h e i r presence would tend to mask a l u n a r t i d e of l e s s than 1 k i l o m e t e r , unless a l a r g e number of readings were a v a i l a b l e f o r a n a l y s i s . The 30-sday set of readings was d i v i d e d i n t o two groups of 14 days each, w i t h two days of readings l e f t unused. Each l4-iday group of readings i n c l u d e d 472 separate height d e t e r m i -nations. However, a l i m i t e d number of these heights were d i s c a r d e d as being o b v i o u s l y erroneous. An example of t h i s i s c i t e d here. The f o l l o w i n g s i x consecutive readings were taken: 116.5 *110 l l g 118 117 119 The 110 km. reading was discarded as being q u i t e obviously an o b s e r v a t i o n a l e r r o r . In the case of the second c y c l e which was examined, a t o t a l of 10 height determinations were d i s c a r d e d . Using one l 4 - d a y group of readings, a s o l a r c o n t r o l graph was made by taking a lty-day average height f o r each 15 minutes o f the day. Such an average, would e l i m i n a t e a l l s i n u s o i d a l v a r i a t i o n s having a p e r i o d of Ik- days from the r e s u l t a n t graph. The d e v i a t i o n of each reading from the s o l a r c o n t r o l was c a l c u l a t e d ; a n d these d i f f e r e n c e s were arranged by l u n a r times i n such a way that any i n d i v i d u a l reading was w i t h i n 74 minutes of i t s c o r r e c t l u n a r time. T h i s procedure produced f i f t y p o i n t s f o r a l u n a r t i d e curve. The random v a r i a t i o n s i n these p o i n t s were found to be very great and to f a c i l i t a t e p l o t t i n g the l u n a r t i d e , a f i v e - p o i n t moving average of the 50 p o i n t s was taken. T h i s was p l o t t e d a g a i n s t l u n a r time on a b a s i s of 12 hours 30 minutes to a l u n a r h a l f - d a y . A g r a p h i c a l a n a l y s i s was made of the r e s u l t a n t curve and the c o e f f i c i e n t s of the l u n a r t i d e components were determined. Samples of these analyses are Included i n appendix 1. T h i s method of a n a l y s i s was d i s c u s s e d w i t h Dr. S. Nash, of the Department of Mathematics, U n i v e r s i t y o f B r i t i s h Columbia, who confirmed the v a l i d i t y of the v a r i o u s steps which were taken i n the a n a l y s i s . 26. IV RESULTS OF THE INVESTIGATION From an a n a l y s i s o f the data f o r the f i r s t l u n a r cycle which was s t u d i e d , an E l a y e r height v a r i a t i o n w i t h a s e m i - d i u r n a l p e r i o d and a maximum amplitude of about 1 km. was found to e x i s t . However, no confirmation of t h i s v a r i a -t i o n was forthcoming from an a n a l y s i s of the f o l l o w i n g c y c l e . I n a d d i t i o n , the phase of the f i r s t v a r i a t i o n d i d not agree w i t h that of the t i d e d e s c r i b e d by Appleton and Weekes. Thus, i t i s f e l t that these data do not c o n t a i n a l u n a r t i d e com-ponent of the magnitude o r phase o f that found by Appleton and Weekes. The presence of a s trongly i o n i z e d l a y e r between 45 and 60 kms. has c o n t r i b u t e d markedly to the d i f f i c u l t i e s o f t h i s a n a l y s i s . The i o n i z a t i o n i s a f u n c t i o n of the sun's a l t i -t idue and i s of s u f f i c i e n t l y h i g h i o n i z a t i o n d e n s i t y to a t t e n u -ate s e r i o u s l y the noon-hour E - l a y e r echoes. On a sample day, readings were taken of the v a r i a t i o n s i n the amplitude of the echoes r e c e i v e d from both the D and E l a y e r s . The v a r i o u s echoes were photographed and samples are presented (see F i g . 10). Some photographs of the D - l a y e r echoes were taken w i t h normal E - l a y e r echoes simultaneously v i s i b l e on the p r e s e n t a t i o n C. R. T. I t was suggested by Mr. J , C. Scott o f the Radio Physics L a b o r a t o r i e s , Defence Research Board, Ottawa, that these echoes might be caused by r e f l e c t i o n from the mountains i n the v i c i n i t y of Vancouver. However, i f t h i s 27. were the ease, such echoes should not be subject to the f a d i n g and v a r i a t i o n In height which the observed echoes show. On s p e c i f i c days, the D - layer echoes e x h i b i t e d f a s t f l u t t e r fades s i m i l a r to those observed on the E - l a y e r echoes at that time. The c h a r a c t e r i s t i c s of the D - l a y e r echoes are h i g h l y v a r i a b l e from day to day and t h i s would not be the case f o r ground wave r e f l e c t i o n s from the mountains nearby. Sample p i c t u r e s are shown where on a frequency of 2.0 mc/s, , the D - layer echoes arej l a r g e r than, approximately equal t o , o r s m a l l e r than the normal E - l a y e r echoes shown w i t h them. An a d d i t i o n a l c o n f i r -mation f o r the existence of t h i s l a y e r i s the a b s o r p t i o n and r e t a r d a t i o n effect of the Delayer upon normal & 4 l a y e r echoes. Prom two 1*1—day s o l a r c o n t r o l graphs which were p l o t t e d , i t i s apparent that the curves are not smooth as p r e d i c t e d by the theory f o r a simple i o n i z e d l a y e r such as that suggested by C h a p m a n ^ ) . i . e . , k=- K j - H Uc, Co-sX, Here, h i s the a c t u a l height of the l a y e r above ground l e v e l and h Q 1 i s the height of the l a y e r maximum corresponding to an i o n i z a t i o n concentrat ion of N 0 e l e c t r o n s / c c . when x, the sun z e n i t h angle — 0 and where N., the i o n i z a t i o n c o n c e n t r a t i o n f o r any other h and x i s g iven by Where Z = k ~ ^ ° H and H i s the scale height of the l a y e r . 28\ F i g . 10 - D-layer Echoes showing size r e l a t i v e to E-echoes Large D-echoes, small E-echoes D and E-echoes equal at noon mid-morning and mid-afternoon Large E-echoes, small D-echoes; early morning and l a t e afternoon. F i g . 11 - E-layer echoes on 200 Ism. presentation 'I I - ' ' . . 29. From the data gathered during t h i s experiment, . there appears to be a d a i l y v a r i a t i o n i n the E - l a y e r height superimposed on the normal s o l a r movement. The movement i s of the order of 0.8" km/s., w i t h a maximum at l o c a l s o l a r noon. Fourteen i n d i v i d u a l readings were used to determine the E - l a y e r height f o r each 15-minute p e r i o d of the day and f o r p u r e l y random v a r i a t i o n i n experimental data, t h i s would permit a n e r r o r e = E r r o r i n each reading jNumber o f readings The accuracy of any s i n g l e height determination i s 0 . 5 kms. Thus, the maximum random e r r o r i n the height of the E - l a y e r at any average 15-minute p o i n t on the s o l a r c o n t r o l graph Is 0 .5 = 0.13 kms. I* Since the v a r i a t i o n s i n the smoothed E - l a y e r heights are g r e a t e r than the c r i t i c a l v a l u e , they must represent a r e a l v a r i a t i o n i n the height of the E - l a y e r and a r e not due to reading e r r o r s . The p i c t u r e which i s presented by these data tends to minimize the noon E - l a y e r r e t a r d a t i o n s because there appears to be a second f a c t o r which v a r i e s the magnitude of noon-hour r e t a r d a t i o n . T h i s f a c t o r i s the degree to which the ionosphere i s d i s t u r b e d a t the time observations are being made. I n the ten-day p e r i o d ending August 11, 1 9 5 I » there / 30. were s i x days which e x h i b i t e d noon-hour r e t a r d a t i o n s o f 2 to 3 kms0 and one which showed a noon-hour r e t a r d a t i o n of 1-|- kms. On the other three days, no noon-hour r e t a r d a t i o n o c c u r r e d . Hence, i n the l 4 - d a y s o l a r c o n t r o l graphs, the presence of the noon-hour r e t a r d a t i o n was somewhat masked by those data which were obtained on days when there was no noon-hour r e t a r d a t i o n . 31. V DISCUSSION By u s i n g the B r e i t and Tuve method of ionospheric sounding, an I n v e s t i g a t i o n was performed to determine the existence of a t i d e In the E - r e g i o n of the K e n n e l l y - H e a v l s i d e l a y e r w i t h a l u n a r s e m i - d i u r n a l p e r i o d . Since no such t i d e was found, i t i s evident that should one e x i s t , i t i s too small to he detected w i t h the methods used i n t h i s i n v e s t i -g a t i o n . From the known accuracy o f the equipment used i n the I n v e s t i g a t i o n , i t i s suggested that any t i d a l v a r i a t i o n s which may have e x i s t e d must have had a c r e s t amplitude l e s s than 0.3 km. Since the work of Appleton and Weekes d i s c l o s e d an E - l a y e r t i d e w i t h a c r e s t amplitude of 0.93 kms., there seems to be a marked c o n t r a d i c t i o n between the r e s u l t s of t h e i r i n v e s t i g a t i o n and those of t h i s one. Chapman has analyzed data from a l a r g e number of meteorological observatories a l l over the w o r l d . The r e s u l t s of these analyses have shown that the amplitude o f the l u n a r -s e m i - d i u r n a l pressure o s c i l l a t i o n i s by no means constant throughout the world. He has shown that the t r e n d i s toward l a r g e r pressure v a r i a t i o n s near the equator, with smaller ones a t o b s e r v a t o r i e s c l o s e to the p o l e s . T h i s Is shown very ade-quately by the map which i s reproduced here from the Proceedings of the Royal Society of London,, S e r i e s A , volume I5I, page 110. 32 I t l a apparent that Vancouver l a unique i n that i t has a smaller pressure o s c i l l a t i o n than any other observatory f o r which data have been analysed. The pressure o s c i l l a t i o n a t Vancouver i s only l / 3 0 t h of that a t Singapore and 1/4 of that i n England. Since the pressure o s c i l l a t i o n at ground l e v e l i s manifest i n the upper atmosphere as a t i d a l movement, i t fol lows that any E - l a y e r s e m i - d i u r n a l t i d e at Vancouver should have a c r e s t amplitude of s l i g h t l y l e s s than 250 meters. I t i s doubtful whether such a small t i d e would be detectable by an equipment such as that used i n t h i s i n v e s t i g a t i o n , unless a very l a r g e quantity of data were a v a i l a b l e f o r a n a l y s i s . I t i s apparent, t h e r e f o r e , that no r e a l c o n f l i c t e x i s t s between the r e s u l t s of t h i s i n v e s t i g a t i o n and the work o f Appleton and Weekes. Furthermore, when the r e s u l t s of both i n v e s t i g a t i o n s are compared w i t h the v a r i a t i o n s i n the magni-tude of the l u n a r - s e m i - d i u r n a l pressure o s c i l l a t i o n s between England and Vancouver, Canada, they provide a confirmation o f the analyses performed by Chapman i n 1935* The work of Appleton and Weekes was performed i n 1937 & n d I93S, which were years of h i g h s o l a r a c t i v i t y ( Z u r i c h Number 120)j whereas, t h i s i n v e s t i g a t i o n was c a r r i e d out i n 1951 at a time when the smoothed Z u r i c h Number was i n the v i c i n i t y of 55» This i s a very low Z u r i c h Number and the Incidence of i o n o s p h e r i c a l l y - d i s t u r b e d days was h i g h . There-f o r e , i t would be d e s i r a b l e to continue t h i s i n v e s t i g a t i o n at 33. a l a t e r date, choosing a time when ionospheric c o n d i t i o n s are s i m i l a r to those under which the i n v e s t i g a t i o n was p e r -formed by Appleton and Weekes. Enough data should then be accumulated to o b t a i n an accurate determination of the magnir< tude of the l u n a r t i d e i n the E - l a y e r at Vancouver Canada, and, i n t h i s way, provide material, f o r a b e t t e r comparison w i t h the l u n a r pressure o s c i l l a t i o n s determined by Chapman. F i g . 12 Map showing l u n a r atmospheric pressure o s c i l l a t i o n s a t various o b s e r v a t o r i e s . V>4 35. VI CONCLUSIONS i • . There i s no i n d i c a t i o n of a l u n a r t i d e w i t h a s e m i - d i u r n a l p e r i o d and a magnitude of 1 km. i n the data gathered d u r i n g the i n v e s t i g a t i o n performed at Vancouver, B r i t i s h Columbia, i n the summer of 1 9 5 1 . Strong I n d i c a t i o n s of daytime D - l a y e r i o n i z a t i o n between 5 5 and 8 5 kms. were found i n these data. These i n d i c a -t i o n s i n c l u d e E - l a y e r a b s o r p t i o n and noon-hour E - l a y e r . r e t a r d a t i o n . I t i s suggested that the i n v e s t i g a t i o n be continued at a l a t e r date when the smoothed Z u r i c h Number i s the same as i t was when Appleton and Weekes performed t h e i r i n v e s t i g a -t i o n s i n 1 9 3 7 . Under these c o n d i t i o n s , the incidence of d i s t u r b e d days would be lowered and one of the many d i f f e r -ences between Conditions i n 1 9 3 7 and 1 9 5 1 would be el imina-ted. I t i s f u r t h e r suggested that a c o r r e l a t i o n be sought between E - l a y e r noon-hour r e t a r d a t i o n and the sun^s z e n i t h angle i n s o f a r as i t a p p l i e s to D - l a y e r i o n i z a t i o n . I t was shown that the r e s u l t s of t h i s i n v e s t i g a t i o n agreed w i t h those of a l u n a r t i d e s i n v e s t i g a t i o n performed by Appleton and Weekes i n 1 9 3 9 . At the same time, these r e s u l t s and those obtained by Appleton and Weekes i n 1 9 3 9 ?6. are i n agreement w i t h the r e s u l t s of extensive analyses performed by Chapman i n 1931 on l u n a r atmospheric pressure o s c i l l a t i o n . 37. ACKNOWLEDGEMENTS The author expresses h i s a p p r e c i a t i o n to the Radio Physics L a b o r a t o r i e s , Defence Research Board, f o r D. R. B. Grant 242 i n a i d and equipment loaned f o r t h i s i n v e s t i g a t i o n , and to Mr. J . C. W. Scott and Dr. T. W. Straker f o r t h e i r a s s i s t a n c e , both p r i o r to and during the i n v e s t i g a t i o n . Thanks i s due to Dr. P. Noakes, Department of E l e c -t r i c a l Engineering of The U n i v e r s i t y of B r i t i s h Columbia, who, as grantee, was responsible f o r the d i r e c t i o n of the p r o j e c t ; to D. W. Moore, student a s s i s t a n t , who c o n t r i b u t e d many ideas and d i d much of the work of equipment c o n v e r s i o n , and to J . S. B e l r o s e , co-worker under Grant D, R. B. 24-3, who helped so much w i t h the tedious work o f data r e c o r d i n g . 3*. LITERATURE CITED Reference No. 1 Thompson, S i r W i l l i a m , "On the thermodynamic a c c e l e r a -t i o n of the e a r t h 1 a r o t a t i o n , " Proceedings of the  Royal Society of Edinburgh. v o l . 11, p. 396. 2 K e l v i n , L o r d , quoted from P e k e r i s , C, L . , "Atmospheric o s c i l l a t i o n s . " Proceedings of the Royal Society of Lflndon /A, 1937, v o l . 158, p. 650. 3 Simpson, Q u a r t e r l y J o u r n a l Royal Meteorological, S o c l e t v T v o l . 44, p. 1, quoted from P e k e r i s , C. L . , Proceedings of the Royal Society of London A , 1937> v o l . 152, p. 650. 4 L a p l a c e , quoted from Appleton, E . V. and Weekes, K . , "On l u n a r t i d e s i n the upper atmosphere," Proceedings  of the Royal Society of London A r 1939, v o l . 171, p. 171. 5 Chapman, S . , "Lunar t i d e s i n the earth*s atmosphere," Proceedings of the Royal Society of London A T 1931, v o l . 151, p. 105. 6 T a y l o r , G-. I , , "Waves and t i d e s i n the atmosphere," Proceedings of the Royal Society of London A T 1929, v o l . 126, p. 169. 39. Reference No. 7 P e k e r i s , C. L , , "Atmospheric o s c i l l a t i o n s , " Proceed- ings of the Royal Society of London A , 1937, v o l . 158, p. 650. 8" Balfour-Stewart , quoted from M i t r a , S, Kv, The Upper  Atmosphere,. C a l c u t t a , Royal A s i a t i c Society of Bengal, 19 k 2. 9 Appleton, E. V. and Weekes, K., ."On l u n a r t i d e s i n the upper atmosphere," Proceedings of the Royal  Society of London A , 1939, v o l . 171, p. 171. 10 Appleton, E. V. and Weekes, K.., "On l u n a r t i d e s i n the upper atmosphere," Proceedings of the Royal  Society of London A T 1939, v o l . 171, p. 171. 11 B r e i t , G . , and Tuve, M . , "A t e s t f o r the existence of the conducting l a y e r , " P h y s i c a l Review, 1926, v o l . 28", p . 554. 12. Terman, P. E,, Radio, engineering, New York, McGraw-H i l l Book Co. I n c . , 194-7. 13 Massachusetts I n s t i t u t e of Technology, Radiation, l a b o r a t o r y s e r i e s , v o l . 5, New York, McGraw-Hil l Book Co. Inc. 14 Cox, J . W., personal correspondence, 1949. 40. Reference No. 15 Chapman, S . , "The a b s o r p t i o n and d i s s o s i a t i v e or i o n i z a t i o n effect of monochromatic r a d i a t i o n i n an atmosphere on a r o t a t i n g e a r t h , " Proceedings of the  P h y s i c a l Society T 19^31, v o l . 43, p . - 2 6 and 4^3. 16 Correspondence with Overseas Engineering Department, B r i t i s h Broadcasting C o r p o r a t i o n , London, England. 41. BIBLIOGRAPHY S p e c i a l Works Brown, C, H . , N l c h o l l * s concise guide, Glasgow Brown Son and Ferguson L i m i t e d . Federal Telephone and Radio C o r p o r a t i o n , Reference  data f o r r a d i o engineers, New York, J . J . L i t t l e and Ives Company, 1946. Jordan, E . C . , Electromagnetic waves and radiating;  systems. New York, P r e n t i c e - H a l l Incorporated, 1950. Massachusetts I n s t i t u t e of Technology, R a d i a t i o n  l a b o r a t o r y s e r i e s . New York, McGraw-Hill Book Company. M i t r a , S. Kv,. The upper atmosphere. C a l c u t t a , Royal A s i a t i c Society, of Bengal, 1942. National Bureau of Standards, Ionospheric radio  propagation. Washington, D. C . , U. S. Government P r i n t i n g O f f i c e , 1942, c i r c u l a r #462. Terman, F. E-. , Radio engineering, New York, McGraw-H i l l Book Company, 1947. Ware and Reed, Communications c i r c u i t s , New York, Wiley and Sons, 1942. . 42. Periodicals Appleton, E . V . , "Gn some measurements o f the equiva-l e n t height o f the atmospheric i o n i z e d l a y e r , " Proceedings of  the Royal Society of London A r 1929, v o l . 126, p. 542. A p p l e t o n , E . V . , and Weekes, K . , "On l u n a r t i d e s i n the upper atmosphere," Proceedings of the Royal Society o,f  London A . 1919. v o l . 171, p. 171. Balfour-Stewart , quoted from M i t r a , S. K . , The upper  atmosphere. C a l c u t t a , Royal A s i a t i c S o c i e t y of Bengal, 1948. B r e i t , G , , and Tuve, M . , "A t e s t f o r the existence of the conducting l a y e r . " P h y s i c a l review. 1926, v o l . 28, p, 554. Chapman, S e > "Lunar t i d e s i n the earth^s atmosphere," Proceedings of the Royal S o c i e t y of London A , 1931, v o l . 151, P. 105. Chapman, S . , "The a b s o r p t i o n and d l s s o s i a t i v e or i o n i z i n g ef fect o f monochromatic r a d i a t i o n i n an atmosphere on a r o t a t i n g earth,'" Proceedings of the P h y s i c a l S o c i e t y , 1931, v o l . 43, p. 26 and 483. K e l v i n , L o r d , quoted from P e x e r i s , C. L . , "Atmos-p h e r i c o s c i l l a t i o n s , Proceedings of the Royal Society of  London A . v o l . 158, p. 650. 43 Simpson, Quarterly, Journal Royal Meteorological  Society, v o l . 44, p. 1, quoted from Pekeris, C. L., "Atmos-pheric o s c i l l a t i o n s , " Proceedings of the Royal Society of  London A r v o l . 158, p. 650. Taylor, G. I., "Waves and tides i n the atmosphere, 1 1 Proceedings of the Royal Society of London A r 1926, v o l . 126, Po 169. r •• •• Thompson, S i r William, "Gn the thermodynamic accele-r a t i o n of the earth's r o t a t i o n , " Proceedings of the Royal  Society of Edinburgh, 1282, v o l . 11, p. 396. A P P E N D I X TABLE I - E - l a y e r Height TABLE I I - D e v i a t i o n from S o l a r Control Curve TABLE I I I - Deviat ion from S o l a r Control Curve arranged, by Lunar Time GRAPH I - S o l a r C o n t r o l Graph f o r 14 days ending J u l y 28", 1951 GRAPH I I - S o l a r C o n t r o l Graph f o r 14 days ending August I I , 1951 GRAPH I I I - Running Averages f o r 14 days ending J u l y 28, 1951 GRAPH IV - Running Averages f o r Ik- days ending August 11, 1951 GRAPH V - E - l a y e r Height f o r August 11, 1951, showing noon-hour Retardation Date JULY Time 0800 15 0900 1000 15 ll 1100 15 1200 Date JULY 15 16 117 117.5 117 H I . 5 116.5 US ' 117 117 l i b 116 115 115 115,5 H 5 . 5 115 22 US ' 112 112 117 H I 116 115 115 115 115 116 115 114 113 112 113 17 12 121.5 117.5 117 117.5 117 l i b 116 l i 6 . 5 116 115.5 114 114 113 114.5 115.5 114 24 123.5 122 122 123 123 120 121 120 122 113 118 118 116 115 114.5 115 J5 19 20 21 124 124.5 125 123 125 120.5 118,5 112,5 118.5 112.5 118.0 117.5 117.5 117.5 116.0 I I 6 . 5 116.0 26 121 120 113.5 119 121 119.5 121.5 120.0 118.0 117.5 116 116.5 116,0 116.5 117.0 27 123 122 122 121 119 113.5 112.5 118 118 117.5 111.5 117:5 118 118 112 117 22 TABLE I E-LAYER HEIGHT SUM CORRECTED AVERAGE AVERAGE Time 0800 15 4~5 0900 15 1000 15 g 1100 15 ll 1200 122.5 121.5 122.5 122.5 122.5 120 120.5 119.5 118.5 118 116.5 I I 6 . 5 116 116.5 117 116. S I I 6 . 5 122,5 122.5 122.5 120.5 121 120.5 119.5 119.5 112.5 II7 . 5 II6 . 5 117 117.5 116.5 116.5 11615 116 121.4 121 120.5 120 119.5 11J.5 116.5 H 7 . 5 117 117 I I 6 . 5 116.5 117 I I 6 . 5 l l 6 . 5 115.5 115.5 119.5 122.5 120.5 123 121 121 120 122.5 122 120.5 120 122.5 120.5 120.5 119 120.5 119.5 120 113 120 120 117.5 120 112.5 119 117.0 118. 5 119 I I 8 . 5 116 119 118 I I 8 . 5 117 119 . 117.5 117.5 l i b . 5 117.5 112 118.0 117 113 116.5 117 113 117.5 117.5 l i b . 5 117 115.5 117.5 117 119.5 117.5 118 113.5 117.5 113.5 120 117.5 119 117. 25 117.5 117 119 117.5 1699.5 1691,0 1690.0 1681.5 1679 1661.0 1657.5 1652.5 1648 1641 1635 1637.5 1627.5 1629.5 1633.0 am3 121.4 120.8 120.7 120.1 119.9 113.6 112 .4 118.0 117.7 117.2 116.8 117.0 116.25 116.4 116.6 I I 6 . 5 116.1 121.4 120.9 120.4 120.0 119.5 119.0 112.5 112.0 117.6 117.2 116.2 116.6 •116.4 116.4 116.4 116.4 116.4 TABLE I I i Deviations from S o l a r C o n t r o l Height 0 Time - lunar*hours , 08.00 08.15 08^0 08.45 09 .ioo 09.45 09.10 09.45 Date J u l y 29 0.9 1.7 2.9 2.1 2.2 1.3 0.8 2.1 30 , 0,4 0.7 1.4 ¥o .4 0.2 -0.2 0.2 0.6 31 ; 1.4 -1.3 1.9 0.1 -0.3 1.8 -0.2 -0.9 Aug, l -0.1 0.7 1.4 l . l 1,7 0.8 0.8 0.25 2 r0.9 -0.8 -0.1 l . l 1.2 0.8 1.3 1.1 3 -1.6 -1.8 -0.6 -0.9 -0.8 -1.2 -1.2 -1.4 -2.1 1. 2 -1.6 -1.9 -1.3 -0.? -0.7 -0.9 5 -0.1 1.2 0 .4 0.1 -0.3 -1,7 -1.7 -2.4 6 2.4 2.2 1.4 1.6 1.2 0.8 0.3 -0 .4 7 ; -1.1 ^1.3 - l . l -0.9 -1.3 -1.2 -1.2 -0 ,4 8 -0.6 1.7 -i . '6 0.1 1.7 1.3 1.3 1.1 9 -#0v6 «o .3 -0.1 0.6 0,7 0.3 0.8 -0 .4 10. «2.3 -0.6 -2,9 -2.8 -0.7 -1.2 -0 .4 11 -0.6 -0.05 -0.6 -0.9 ^0.2 -0.2 0.3 0.6 46. TABLE" I I I D e v i a t i o n from S o i a r C o n t r o l Corrected and Tabulated on Lunar Time Time - l u n a r hours 13.00 13.15 1^30 13.45 14.00 14.15 1^-30 Date J u l y 29 2.85 1.5 2.6 1.2 O .3 0.3 3.25 30 -.0.3 o,3 -1 .2 0.25 ° ' I 0.1 0 31 1.2 0 - 2 , 1 - 0 . 2 - 3 . 0 .-1.8 Aug. 1 -1.1 - 0 . 8 -1 .0 ~0.8 0 - O . 3 1.4 2 0.2 : 0.5 - 0 . 8 - 0 . 6 -1 .4 -1 .7 - 1 .0 3 — 1.1 0.8 1.0 0.2 0 .4 - 0 . 4 i -1 .0 - 0 . 3 - 0 . 1 0.6 0.25 -1.1 I - 0 . 4 0.25 -1.1 I 9 3 % 2 .0 .4 .6.5 2.1 -0.3 .0.25 1,25(7; 6.15(^0.2 ^0.45 -0.75 -5>3 1.45 3.25 I7I W. (2) C7) (7) C7) (6) 16) Time l u n a r hours 011.00 01.15 01.^0 01.45 02.00 02.15 02.30 02.45, Date J u l y 29 30 31 Aug. 1 2 3 i I I 9 10 11 .-0.6 -O .05 - 0 . 6 - 0 . 9 - 0 . 8 - 2 . 3 - 0 . 2 - 0 . 6 - 0 . 3 ^2.9 0.$ SUM (A.M. (P. M. 0.6 (1) I .85 (8) 6.10 (8) - 0 . 6 (1) - 1 .4 (9) Ii? - 0 . 8 (1) -1.55 (8) - 2 . 5 (2) - 7 . 8 (9) -m w T i d a l 0;23 C o e f f i c i e n t s ) 0.68 -0.15 -0.17 - 0 . 2 0 - 0 . 8 7 ^ 0 . 0 7 0.29 H o n r s P . S . T . 11 noon Hours P. S. T. 

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