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Distribution: Controlled: all requests toChief, Office of Naval Research, Attn:Code 102-OS. Arlington, Va. 22217.

AUTHORITY1978 per document markings; ONR ltr., Ser93/160, 10 Mar 1999

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CONFIOMfIAMMC REPORT 006

Volume 2

February 1972

i D

I

3 E2z ftf

Omit From General Bibliographit Listings.

OCEAN SCIENCE PROGRAM

MAURY CENTER FOR OCEAN SCIENCE

Department of the Navy

Washington, D.C.

This document may be further distributed by the holder only with specific prior approval of theDirector, Long Range A•1 ic Propagation Project (ONR Code 102-OS).

IAL

W"AT ONAL SECURITY I71:CP=AT1ON0

MC Report 006rhsUauthorized DLSgIQSz '@ Su beot to Criminal Volume 2

Li LONG RANGE ACOUSTIC PROPAGATION PROJECT

THE PARKA 1A EXPERIMENTP CPACIFIC ACOUSTIC RESEARCH KANEOHE-ALASKA

St1?Y1E 70SIFICATION" ; S C '• : *:SO N , 0 7 ' • F +X L : C 1 ) +T I V E O R D ES R 1 1 6 5 2

Shrc'-- FXIC"TIVDWN0D AT TWO

S~~~YEAR INTERVALS "

"DECLASSIFIED ON DECEMBER 3it 1/

OCEAN SCIENCE PROGRAMMAURY CENTER FOR OCEAN SCIENCE

Department of the Navy

Washington, D.C.

CONFIDENTIAL

CONTENTS

FOREWORD ............................................................ v

ACKNOWLEDGMENTS .................................................... vi

1. THE EXPERIM ENT ...................................................... 1

INTRODUCTION ...................................................... 1

PRE-EXPERIMENT OPERATIONS ........................................ 1

Long Range Transits ................................................ 1Operations During SEA SPIDER Implantment Attempts .................... 3

ACOUSTIC PROPAGATION LOSS AND ARRIVAL STRUCTURE,SHIP RUNS (EVENT 9) ............................................... 3

G eneral .......................................................... 3CON R A D ........................................................ 4SA N D S .......................................................... 4MARYSVILLE....................................................4REXBURGY ... .................................................... 4Aircraft ......................................................... 4

LONG RA .3 "E PROPAGATION LOSS, AIRCRAFT RUNS(EV E !. 13) ........................................................ 5

PROPAGATION LOSS AND TEMPORAL FLUCTUATIONOF CONTINUOUS WAVE (CW) SIGNALS (EVENT 11) ...................... 5

G eneral .......................................................... 5CO N R A D ........................................................ 5SA N D S .......................................................... 5M ARY SVILLE .................................................... 6REXBURG ...................................................... 6

DATA TRANSMISSION ................................................. 6

TI. REGIONAL OCEANOGRAPHY ............................................ 7

THE NORTHEASTERN NORTH PACIFIC OCEAN ............................ 7

THE FLIP AREA ...................................................... 8

III. OCEANOGRAPHIC RESULTS ............................................ 10

PART A: ANALYSIS OF PARKA II-A DATA ............................... 10

G ENERAL ......................................................... 10

TEMPERATURE-SALINITY (T-S) DIAGRAMS ............................. 10

TEMPERATURE STRUCTURE ......................................... 12

SEA SURFACE TEMPERATURE ....................................... 13

SALINITY STKUCTURE .............................................. 13

SPMFDINk PAON BLAWNOT FILMED ."-

CONTENTS

SIGMA-T PROFILES ................................................. 14

ENVIRONMENTAL VARIABILITY ..................................... 16

PART B: THERMISTOR CHAIN OBSERVATIONS ........................... 16

THERMISTOR CHAIN AND ANCILLARY EQUIPMENT ..................... 16

Capability ........................................................ 16Sensors .......................................................... 18

CONFIGURATION ................................................... 18OPERATIONS ....................................................... 18

DISCUSSION ........................................................ 19

Isotherm Contour Plots .............................................. 19Event 9-1 (From 220 N to FLIP) ...................................... 19Events 9-2 and 9-3 (Runs North of FLIP) ................................ 19Events 9-4 and 9-5 (Southwest Runs) ................................... 21

GENERAL ......................................................... 25

IV. SOUND VELOCITY STRUCTURE ......................................... 26

GENERAL ........................................................... 26

PROPAGATION LOSS AND ARRIVAL STRUCTURE,SHIP RUNS (EVENTS 9 AND 11) ....................................... 27

Summary ....................................................... 27Figure Construction ................................................. 28

1. Sound Velocity Profiles .......................................... 282. Contoured Cross Sections of Sound Velocity ......................... 36

Shallow Sound Velocity Structure North and South of FLIP(Events 9-1, 9-2 and 9-3) ......................................... 37

Shallow Sound Velocity Structure Southwest of FLIP

(Events 9-4 and 9-5) ............................................. 38Shallow Sound Velocity Structure North of MAHI

(Events 11-1 and 11-2) ............................................ 51

LONG RANGE PROPAGATION LOSS, AIRCRAFT RUNS (EVENT 13) ........... 51

Summary ...................................................... 51Adak and Due North Aircraft Runs (Events 13-1, 13-2 and 13-5) .............. 52San Diego Aircraft Run (Events 13-3 and 13-4) ............................ 77

FEATURES OF SOUND VELOCITY PROFILES AT THEFLIP/SANDS SITE ................................................. 77

COMPARISON OF SOUND VELOCITY DATA FROM DIFFERENT SYSTEMS ..... 78

XBT's Compared with STD System ..................................... 78Comparison of Computed and Measured Sound Velocities ................... 78

REFERENCES ............................................................ 88

iv

FOREWORD

The PARKA iI-A Report consists of three parts, of which

the present volur.me is Volume 2. The Oceanographic Me'a-surements. Volunms I and 3. wt ch will be bound separately.

will describe "lie Acoustic Measurements and The Propaga-

tion Modeling, respectively.The Report was generated by a cooperative effort whi:h 4

was an extension of the teamwork of the experiment itself.

The individual writings of a number of scientists from the

participating organizations were edited and interwoven to form

each Volume. The principal contributors to Volume 2 were

K. W. La(,k;e, L. C. Breaker and J. K. Duncan of the Naval

Oceanographic Office, and K. W. Nelson of the Naval Undersea

Research and Development Center. Contributors to the writing

of the other two volumes will be listed therein.

Special acknowledgment is also gratefully given to the many

individuals who made the achievement of the experiment

p- ssible by their dedicated efforts in the face of great difficulties

at sea.

R, H. NICHOLS

Chief Scientist, PARKAj

vI

S- 1

ACKNOWLEDGMENTS

On behalf" of the Navy Managers responsible for the "ARKA experi-ments, the contributions of senior officers of the Niavy, members ofthe scientific community who participated in PARKA II-A, and sea-

faring men, both naval and civilian, who contributed in various waysare gratefully acknowledged.

Dr. R. H. Nichols, Bell Telephone Laboratories, served as Chief"

Scientist, and in that role was responsible for the scientific planningand execution of the PARKA series. Mr. R. W. Hasse, Navy Under-water Sound Laboratory, was the Deputy Chief Scientist. Mr. A. J.Hiller and Capt. A. E. White. USN (Ret.) served consecutively asProject Coordinator. Mr. K. W. Lackie, Naval Oceanographic Office,acted as the Scientist-in-Charge of Oceanographic Operations. Capt.R. H. Smith, USN, and Lt. Cdr. E. E. Flesher, USN, ASWFORPAC,directed naval aspects of the operations.

The assistance of those providing broad scientific planning, as wellas facilities and support in conducting the entire PARKA 11-A Experi- :

ment has been acknowledged in Volume ; of this report. A few othersshould be listed, however, as having made a significant contribution tothe success of the environmental effort in the experiment.I

From the Navy Underwater Sound Laboratory: T. A. Bender, J. F.

Crotty, Lt. Cdr. J. M. Heiges, L. C. Maples, W. H. Thorp, R. H. Smith,H. B. Williams, R. F. LaPlante, F. C. Walsh, and R. K. Dullea.

From the Naval Undersea Research and Development Center:P. A. Hanson, C. T. Smallenberger, and F. K. Adams.

From the Naval Oceanographic Office: B. A. Watrous, C. L. Davis,and N. V. Lombard.

From Fleet Numerical Weather Central: Lt. N. L. Perkins and iLt. Cdr. K. G. Hinman.

From Fleet Weather Central, Pearl Harbor: Lt. C. H. West. L.J.g. D. R. McConathy, Jr., and Lt. j.g. H. L. Peterson.

From the Hawaii Institute of Geophysics: R. C. Latham, AntaresParvulescu, Edward Houlton, N. J'. Thompson. Romondt Budd, R. G.

= ~Zachariadis, B. E. Gottensburen, and J. R. Ryan. "

From the Lamont-Doherty Geological Observatory: J. 1. Ewing,

C. C. Windisch. Peter Buhl, and Sydney Griffin.Obviously, many other individuals and organizations have contri-

buted to the planning and execution of the experiment. Although it

is not practical to list them all here, their contributions are most grate-fully acknowledged. /

J. B. HERSEYP.7 _Director, Maury Centerfor Ocean Science

vi

_~~ ......._ 2

THE EXPERIMENT

i. THE EXPERiMENT (Maury Center for Ocean Science, 1969a), andare summarized in Volume I of this report.

INTRODUCTION In this volume the oceanographic observationsand results will be associated with the cor-

The PARKA I1-A Experiment was per- responding acoustic measurements.

formed in the North Pacific Ocean in November PARKA II-A was a modification of the

and December of 1969 as a cooperative venture originally-planned PARKA i1 program which(f fourteen Navy and civilian laboratories and envisioned SEA SPIDER as the receiver plat-

other organizations under the sponsorship of form. When the SEA SPIDER installation

the Office of Naval Research (ON R). It followed p.oved unsuccessful, R/V FLIP was substi-

PARKA I as the second of a series of three tuted and the program revised to accommodateexperiments designed to acquire a comprehen- the change. The new program cemprised twosive bank of detailed acoustic and oceanographic parts, PARKA Ili-A and PARKA i1-B. Thedata to be employed in the development and latter, which included a seasonal repeat of parttest of acoustic prediction models. of PARKA Ili-A, was performed in March of

PARKA Il-A was a combined oceano- 1970; it will be reported separately.graphic-acoustic experiment, in which the FLIP was stationed during PARKA Il-Aoceanographic effort was designed to provide at approximately the same position as during

a better understanding of the acoustic results. PARKA 1, 330 nautical miles north of OahuA description of PARKA II-A acoustic pro- in water 18000 feet deep, and was securelygrams and a discussion of the results is con- moored to keep her closely on station. Various

tained in Volume I of this report. acoustic runs utilizing both ship and aircraftWith each individual acoustic event, a were made in the area, either orginating or

series of concurrent oceanographic observa- terminating at the FLIP site.tions was taken in order to describe the environ- The ship runs (Fig. I) were made on threemental conditions along the acoustic path which bearings from FLIP, 000°T, 180°T, and 247°T

caused the observed propagation characteris- to ranges of 300 to 500 nautical miles, over atics. Wherever possible, environmental data variety of bottom topographies. The aircraftwere collected at the acoustic source, the re- runs (Fig. 2) were made between FLIP and

ceiver, and at one to three points between them. Adak, between FLIP and the Alaskan coastThis :s similar to the environmental program due north (the PARKA I track), and betweencarried out in PARKA I (Maury Center for FLIP and San Diego.Ocean Science, 1969b, and Lackie, 1971).A complete dcscription of ship and aircraftschedules is contained in the PARKA 11 Sci- PRE-EXPERIMENT OPERATIONSentific Plan (Maury Center for Ocean Science,I1969a). Long Range Transits

The oceanographic effort was divided into All PARKA ships collected bathymetric

several distinct phases to coincide with the profiles and limited oceanographic data onacoustic experiments. These experiments, or their transits to the Hawaiian are, for PARKA

Events, which are outlined below, are described operations. These transits were designed toin detail in the PARKA i1 Scientific Plan cover the same tracks that Navy aircraft would

I

THE EXPERIMENT

EVENT 9-1 1 J I -T-'T---T-T-T---1-7-T----

360 157o44'W A.--

lIongittude

340

320 -

300 - FLIP

-• 270 35' N Notes;J200 1570 44 W I 9-1,S 28° )'*•330 nii n long

-33 209-2 1 9-3: - Fig. 1 - Track Chart of Event 9 (Propagation Lous

2..-500 0tms togq and Arrival Structure)260 9 9-4 k9-5

24eV 1 400m"tesat lon670 4

220~22°f OAHU

1660 1620 1580 1540 150oWest Longitude

EVENT 13180800, 140000' leo6e0

60- 14-0 600o000"

" 'p

ADAKa.,"

N

SEATTLE

40\ 40.00,- • 00

%54 SAN OIEWjFLIP . 3- 3

2 r7* 3 5ýN157*44'W

* ,

HONOLULU"'

150 I 150O00'I 00,

18000' 140'00' I00000

Fig. 2 - Track Chart of Event 13 (Long Rang. Propagation Loss, Aircraft)

2

THE EXPERIMENT

traverse later in the experiment during the unsuccessful attempts to implant SEA SPIDER,

propagation loss studies of Event 13 (Fig. 2). as well as during other local operations in theI. R/V CONRAD - Lamont-Dohetly area. In addition, HI(i made current measure-

Geological Observatory (LDGO): Adak ments from R/V TOWNSEND CROMWELLto the site where FLIP was to be anchored and R/V MAHI. These data, %-i,,,h were col-(nominally, 27°35'N, 157°44'W). This lected prior to the commencement of PARKArun corresponded to Events 13-1 and II-A experimental operations in November,13-2. were intended partly to support the SEA SPI-2. USNS SANDS - Navy Underwater DER implantment, and partly to provide dataSound Laboratory (NUSI): San Diego to on temporal variability of sound velocity struc-FLIP site, corresponding to Events 13-3 ture; they are not presented here. However,and 13-4. they are included in the PARKA archival data3. USS MARYSVILLE - Hawaii Insti- file. The PARKA II-A data are available totitute of Geophysics (HI.G): Seattle to qualified agencies upon application to theFLIP site (Latham and others, 1969) cor- Director, Maury Center for Ocean Science,responding to Events 13-7 and 13-8, which Code 102,OS, Office of Nav,' Research,were cancelled after FLIP was damaged Arlington, Virginia 22217.by high seas. (See Rudnick and Hasse,1971.) ACOUSTIC PROPAGATION LOSS AND4. U•S REXBURG - Naval Undersea ARRIVAL STRUCTURE, SHIP RUNSResearch and Development Center (EVENT 9)(NURDC): San Diego to FLIP site. General

The track due north to the Alaska Peninsula,corresponding to Events 13-5 and 13-6 (the During Event 9, which was the first prop-

latter was cancelled when FLIP was damaged), agation experiment, CONRAD was the sourcehad been adr ,uately surveyed during PARKA I ship and FLIP and SANDS were located at

in 1968, In addition, UFC&GSS MCARTHUR the receiver position, approximately 27°35'N,collected bathvmetr;,; data on her transit 157 044'W. CONRAD dropped explosivebetween Hawaii and Seattle in May. Profiles charges on five radial runs from FLIP (Fig. I).

of these bathymetric data r' - plotted versus I. Event 9-1: from 22°N (335 nautical milesrange and are included as Figs. 36 through 39. south of FLIP) north to FLIP.

Superimposed on these bathymetric profiles 2. Event 9-2: from FLIP due north to a

arc the sound velocity profiles that were pre- range of about 500 nautical miles (36°N).dicted by Fleet Numerica, Weather Central 3. Event 93. frooi the end point of Event 9-2

(FNWC). due south back to FLIP.4. Event 9-4: from FLIP to a range of about

Operations During SEA SPIDER 400 nautical miles on a great circle havinglmplantment Attempts a bearing of 247°T at FLIP.

During various periods in August, Septem- 5. Event 9-5: from the end point of Event 9-4ber, and October 1969, SANDS, CONRAD, back on the same great circle to FLIP.and MARYSVILLE collected limited quantities Sound velocity profiles collected on each of theof oceanographic data in the PARKA area, above events are plotted against range in Figs.These observations were made during the two 22, 23, 24, 28, and 29. Contoured cross sections

3

JIL

THE EXPERIMENT

of the same data are shown in Figs. 25, 26, 27, and to a range of 250 nautical mile% on Events

30. and 3 1. These are presented with the discus- 9-4 and 9-5. XBT's were taken about midwaysion of sound velocity structure in Section IV. between stations, except between 19 and 23

As the source ship CONRAD advanced November, when MARYSVIILILEs XBT re-along each run at a speed of about 9.5 knots, corder was inoperative. Shallow velocimeterMARYSVII.E and REXBURG took a series stations were taken at close intervals duringof positions between CONRAD and FLIP, that period. A summary of MARYSVILLEcollecting environmental data along the acoustic operations during PARKA II-A is given in ipath. In this manner, concurrent oceanographic Latham (1970).data were collected over as much of the path as REXBURG

Ai possible.The N U R DC thermistor chain was mount,

CONRAD ed on REXBURG for PARKA Il-A. This chainOn each run CONRAD collected a 2500- measures temperature continuously in time at

foot expendable oathythermograph (XBT) 47 points between the surface and a depth ofrecord every six hours (approximately 55 nauti- 220 meters (Hansen, 1969, LaFond and L.a-cal miles), or more frequency if a significant Fond, 1971, Smith, 1969). REXBURG followedchange in surface temperature was noted. Sea a plan simliar to that of MARYSVILLE, taking

P• surface temperatures were taken every two a series of positions between source and re-hours. In addition, a deep salinity-temperature- ceiver. However, REXBURG remained closerdepth (STD) station was occupied at the begin- to the source ship CONRAD in order to moni-fning and end of most runs. tor more effectively the small scale temperature

SSANDS variations at shallow depth near the acousticsource. Chain data were collected to a maximum

SANDS took two XBT's each day during range of 330 nautical miles on Event 9-1, 265the entire experimental period. In addition, deep nautical miles on Events 9-2 and 9-3, and 400velocimeter measurements (temperature and nautical miles on Events 9-4 and 9-5. REX-sound velocity versus depth) were made on BURG also carried out a 48-hour drift stationrour occa~sions during the experiment when at maximum range (265 nautical miles) betweenacoustic operations permitted. A time series Events 9-2 and 9-3 to investigate time seriesplot of these deep velocimeter measurements effects. Whenever possible XBT data wereis shown in Fig. 41. Profiles of SANDS's XBT collected for comparison with the thermistordata, converted to sound velocity and plotted chain results. Selected results from the chainversus time, are displayed in Fig. 42. were coded and transmitted as BT's. These --,e

MARYSVILLE included in Figs. II through 15. Because ofthe unique nature of the thermistor chain data,

MARYSVILLE was the primary oceano- Section III, Part B, of this volume deals ex-graphic ship of PARKA II-A. During most of clusively with results of chain operations inthe experim'nt MARYSVILLE took a series PARKA II-A.of positions approximately halfway betweenSANDS and CONRAD. Deep velocimeter sta- Aircrafttions were taken every 20 to 30 miles to a range Aircraft expendable bathythermographof 180 nautical miles on Events 9-1, 9-2 and 9-3, (AXBT) flights were scheduled once on each

4

c

THE EXPERIMENT

radial run, usually when CONRAD was close Diego to FlIP (23 November). The tempera-to maximum range from FLIP. These are called ture profiles resulting from tht .c AXBT's wereShort AirCraft (SAC) flights. Drops were to be converted to sound velocity using archivalmade every 24 miles out to a range of about 330 salinities and Wilson's equation lWilson, 1960).nautical miles on Event 9-1 and 500 nautical and are plotted against range from 1-1.11 inmiles on Events 9.3 and 9-5. The flights occurred Figs. 34 and 35,on 18, 23, and 28 November, and were num-bered SAC-I, SAC-2, and SAC-3. respectively. PROPAGATION LOSS AND TEMPORAl,Because of operational problems aboard the FLUCTUATION OF CONTINUOUS WAVEaircraft, only I I out of 14 drops were good on (CW) SIGNALS (EVENT il)SAC-I. 20 out of 21 on SAC-2, and none out Iof 21 on SAC-3. The AXBT's extended to adepth of 1000 feet and gave an almost instan- Event I I was schedu .-d to take placetaneous "snapshot" of the near-surface environ- along the same track as Events 9-2 and 9-3

ment over long stretches of ocean. Converted north of FLIP, and was to consist of it projectorto sound velocity, these data are included in tow by CONRAD out to a rsnge of 5WX) nauticalFigs. 22 and 24. miles (I -I) and back to FlIP (11-2). However,

the damage to FLIP prior to the commence-ment of the exercise on I December precluded

LONG RANGE PROPAGATION LOSS, the execution of the event as planned. MARYS-AIRCRAVr RUNS (EVENT 13) VILI.E and REXBURG, who had already

started north on Event Il-I, returned to FLIP.Event 13 was scheduled to consist of four Their participation in PARKA Il-A ended a fcw

round trip L.ong AirCraft (LIAC) flights from days later. A shortened version of the eventFLIP to Adak, to San Diego, due north to was eventually carried out with CONRAD asAlaska, and to Seattle. Explosive charges were source ship and MAHI as receiving ship. Theto be dropped on both runs on each track, with revised Event I I- I was run due northward fromAXBT measurements every 24 miles on the MAHI's position at 26°09'N, 157041'W toflights inbound to FLIP only. about 33020'N. a distance of 430 nautical miles

FLIP was damaged by heavy seas on I (Fig. 3). Profiles and contoured cross sectionsDecember (Rudnick and Hasse, 1971) which of sound vclocity data taken during Event IIended its participation in PARKA Il-A. At this are shown in Figs. 32 and 33, respectively.time, five of the eight flights had taken place(Fig, 2): CONRAD

I. LAC- I from Adak to F AIP CONRAD continued to take XBT's every2. LAC-2 from FLIP to Adak six hours as during Event 9, and occupied a3. LAC-3 from San Diego to FLIP deep STD station at the beginning and end of4. LAC-4 from FLIP to San Diego Event Il-1.5. LAC-5 from FLIP due north to 550NFlights LAC- I and LAC-3 yielded AXBT SANDS

data: 15 of 66 AXBT's dropped were good on SANDS continued to collect XBT's everyLAC-I from Adak to FLIP (17 November), 12 hours at her position near the FLIP siteand 69 of 88 were good on LAC-3 from San and occupied one deep velocimeter station.

5 1

THE EXPERIMENT

EVENT II dures and standard NODC oIgs. The data wereI I I T Ir T I I I transmitted by voice radio to Naval Oceano-

graphic Office (NAVOCIANO) personnel340o located at the PARKA Operation Control Cen-

.- ter (0CC') at Pearl Harbor. Hawaii After pre-liminary checking, the data were punched on:' card% recorded on magnetic tape, computer

-- o,, ' plotted for addit; nal checking, corrected, andTtaok- , ffo,, mi transmitted by direct wire from Fleet Weather

•) .AM, Central (l-WC). Pearl Harbor to FNW('. Mon-

26o 26°o9 N .. tercy. California by FNWC and FWC personnel.As part of the archives, they were available toupdate the PARKA propagation loss predic-

22o lions made by FNWC, and for Fleet use.SoAMLJ Thernistor chain data were handleu in a

IooL I A -1 L_ I _. L-_-L-I__A__L similar manner, except that not all the data were1O 0 1620 [Sao 1540 5 transmitted in real time. Hourly averujes of

'st LongitudOe temperatures at each measured depth were cal-Fi•. 3 - Track Chart of Event 11 (Propagation Loos culated at sea, and selected averages were coded

,nd Temporal Fluctuation of CW Signals) and transmitted as BT's. The remainder of the

MARYSVILLE data were analyzed later by computer and firmthe basis for the discussion in Section I I1, Part B.

MARYSVILLE had already left the area AXBT data were hand-carried from Barberswhen the acoustic phase of Event I I -I started Point Naval Air Station to H1-I1 and FWC Pearlon 8 December. However, the XBT's and velo- for analysis. After checking by PARKA person-cimeter stations she collected along the Event nel, they were sent to FNWC in the same man-

I I track during the period I through 4 [Cecember ner as the other oceanographic data.are included in the Event I I data file because The velocimeters on MARYSVILLE andthey are considered close enough in time to be SANDS mc- red sound velocity uirectly. Thepertinent to the experiment. STE2. system on CONRAD measured both tern-

REXBURG perature and salinity as a function of depth,from which sound velocity was computed by

Thermistor chain and XBT data collected Wilson's equation (Wilson, 1960). XBT's,on the Event I I track by REXBURG from I to AXBT's, and the thermistor chain measure only4 December are considered to be a part of the temperature as a function of depth. FNWC cal-Event I I data for the reasons cited above for culated most of the sound velocity data citedMARYSVILLE. Thermistor chain results in this report by combining XBT, AXBT, andare discussed in Section Ill, Part B. thermistor chain temperatures with assumed

salinities based on archival Nansen cast dita.DATA TRANSMISSION A comparisoa of direct!y-measired sound

All XBT, STD, and sound velocimeter velocities and sound velocities computed fromdata were coded at sea using standard National temperature and salinity data is presented inOceanographic Data Center (NODC) proce- Section IV of this report.

6

REGIONAL OCEANOGRAPHY

I1. REGIONAL OCEANOGRAPHY Several major currents and current sys-tems (gyres, loosely), are located in the north-

THL NORTHEASTERN NORTH eA.2lueIC eastern North Pacific Ocean. The paths of theOCEAN major currents form a geographical framework

The geographic beundaries for PARKA witnin which various near-surface water masses

lU extend northwestward from Hawaii to Adak are located (see Fig. 4). These prevailing cur-and from Hawaii eastward to San Diego, and rents help to replenish and thus preserve thetogether with the coast of North America and characteristic properties of the existing near-

the Aleutian chain enclose a large portion of the surface water masses in this region. Two majornortheastern North Pacific Ocean. This ocean currents flow eastward along the subarcticarea can be subdivided into a subarctic region boundary: the Subarctic Current to the north,

to the north and a subtropical region to the south. and the North Pacific Current to the south, thisThe boundary between these regions lies ap- second current being an extension of the Kuro-proximately on a great circle path from Tokyo shio Current. Tthe North Pacific Current carriesto Los Angeles, and in mid-ocean is located in water that is warm and saline in comparison tothe vicinity of latitude 45°N (Subarctic Con- the Subarctic Current. The Subarctic Currentvergence). divides before reaching the North American

18000' 14000' 10000 6060 6~*.00a 00w 0

LCGEND

Srcmm Approx. WaterSubacticMass Boundaries

Paci tfic / Subarctic ConvergenceWater / - North Pacific Current

S-----Subarctic Current. .... " • ......... California Current

-- California Current

Extenion

!!4 °0 , .., 4 0 0

00 10, 0040Western Eastern•e .... .

North NorthPacific Pacific .

Central Central

.Equatorial,,. ,t" Pacific '•

150 Water 15*00o 00180000 140000' 100000]

Fig. 4 -- Major Water Masses and Current Systems in the Northeast Pacific

7


coast, part being diverted to the north, and part Subarctic Pacific Waters are cold and of low

to the south. The northern extension forms a salinity.loop in the Gulf of Alaska (the Alaskan Gyral) The same subarctic water mass extendsand the southern extension becomes the Call- south between the eastern boundary of Northfornia Current. An extension of the California Pacific Central Water and the west coast ofCurrent eventually flows southwestward toward North America, mixing with Equatorial Pacificthe c .iator passing just south of the Hawaiian Water as it penetrates this subcoastal region.Islands. The North Pacific Current also turns This mixture of subarctic and equatorial waters,

southward. Its flow pattern in the area is not located south of 45'N and off the coast of

clearly defined, but it appears to form a complete California, has been given the name Transitionloop or gyre, at least during the summer and has Water. Between the North Pacific Central Waterbeen named the Eastern North Pacific Gyral Masses and the Pacific Subarctic/Transition

with its center located northeast of Hawaii Water Masses, a boundary region follows ap-

(Seckel, 1962). proximately the subarctic-subtropical divide

The Northeast Pacific contains a number along the western side of the California Current.

of large water masses, each of which possesses This boundary region constitutes what is called

characteristic properties. Water masses can be the Boundary Water Mass. It is typified by pro-

idenified through their respective temperature- nounced variations of temperature and salinitysalinity relationships or "signatures". Some across it, and attributes of neighboring water

typical ones are presented in the following Sec.. masses are often found here (Christensen andtion in Fig. 5a. Starting just north of Hawaii and Lee, 1965).

looking northwest toward Adak, the following TAmajor water masses are encountere-' between themixed layer and the bottom: North Pacific Cen- Due to the fact that most oceanographictral Water, North Pacific Intermediate Water, measurements made during PARKA Il-A werePacific Deep Water. North Pacific Central concentrated in a relatively small area north ofWater is characterized by decreasing tempera- Oahu, Hawaii, the oceanographic features ofture and salinity with depth, a temperature this area deserve a more detailed discussion.range of 18'C to I I C, and a salinity range of The area is roughly circular, with its center35.00°/,o to 34.00%/ (Sverdrup and others, located at the FLIP site, and has a radius of1942). North Pacific Intermediate Water is approximately 500 nautical miles. It is anlocated below the North Pacific Central Water oceanographically complex transition regionand is found over most of the North Pacific containing varying proportions of several(Reid, 1965). It is characterized by a core of adjacent water masses. In addition, the distri-low salinity water and has a minimum value of butions of temperature and salinity in the areaabout 34.00oI/owhich occurs at 600 meters at are not constant from one year to the nextthe FLIP location. Pacific Deep Water occurs (Seckel, 1969). Eddies and turbulence arisingbelow 1000 meters and has a temperature range from current flow around the Hawaiian Islandsof 4C to 1.5°C and a salinity range of 35.50/oo/ may be present, and there is a zone of con-to 35.70'/°o. This deep water mass is quite uni- vergence between the North Pacific Currentform and originates in high southern latitudes. and the California Current Extension in the

North of the Subarctic Convergence, Subarctic southern part of the region (McGary andPacific Water spans the entire Northeast Pacific. Stroup, 1956).

8


In the vicinity of FLIP at least three During November and December, themajor water masses are consistently found: mixed surface layer in the FLIP area is wellNorth Pacific Central Water, North Pacific defined. It ranges in depth from a little less thanIntermediate Water, and Pacific Deep Water. 45 meters to a little more than 90 meters. TheIn the upper layers, the relative proportions of average layer depth is slightly greater in Decem-the various water masses appear to vary signifi- ber. At the FLIP site, surface temperatures arecantly with time and with slight changes in generally in the range of !I° C to 24°C, andlocation. From just below the mixed layer down the surface salinity ordinarily is about 35.00%0/.to 200 to 300 meters, a mixture of Eastern and Large-scale current flow past the HawaiianWestern North Pacific Central Water appears Islands causes the formation o. ,.ddies whichto be present. Eastern Nortit Pacific CentralWater can be distinguished from Western North have been found on both sides of the islandoPacific Central Water by its lower values of chain and identified through geographic plots •

Paii etrlWtrbyislwr auso of certain isotherms. Wyrtki (1967) found 'Isalinity with increasing depth. From about 275

eddies in this area with dimensions on themeters down to almost 1000 meters, North enPacific Intermediate Water exists, with Pacific order of il0 nautical miles, and 3 life span ofDeep Water found below 1000 meters. Roden a few months. He also found large-scule ocean

turbulence to be associated with these eddies.(1970) defines the zone of transition between tsubarctic water and subtropical water occurring Recent deep ocean temperature measure-at the northern end of the FLIP area as lying ments through the FLIP area have revealed abetween 32°N and 42°N latitude. Thus, sub- definite temperature inversion toward thearctic waters may at times intrude into the bottom (Latham and others, 1970). A tempera-northern extremity of the FLIP area. On rare ture minimum was found to occur at about 3800occasions, intermediate and shallow equatorial meters. Temperature increases with depthwaters may be found at the southern edge of beyond this level to the bottom, as the resultthe area. of adiabatic heating (Roden, 1970).

9

I

. ~ ~- - kkM M..~L~M. Z *- - -

rr

OCEANOGRAPHIC RESULTS

111. OCEANOGRAPHIC RESULTS STD 5tations during PARKA 1I-A (normallyat the beginning and end of each acoustic run),no attempt has been made here to contour themeasured data spatially because of the greathorizontal separation between observations.

GENERAL However, CONRAD STD data are included in I

The foregoing discussion of the ocean en- the vertical cross sections of sound velocityvironment in the PARKA 1I-A area was based presented in Section IV.on existing literature. The following discussionof the ocean environment in the general vicinity TEMPERATURE-SALINITY (T-S) DIAGRAMSof the FLIP/SANDS location (27'35'N, Between 17 November and 10 December,157°44'W) is based on data collected during the CONRAD occupied nine STD stations. All butexperimental period, November and December one of the stations were located along the north-1969. Oceanographic and acoustic data were south track through the FLIP site between 36°Ncollected only along several tracks terminating and 22 0N latitude. T-S diagrams, constructedat the FLIP site, and the discussion will be from these data, identify the various waterlimited to the area of these observations. Vertical masses and help io explain certain variationsprofiles of certain oceanographic parameters found in the sound velocity structure. An ex-and the variability of the environment near the ample of such a T-S construction is shown inFLIP site will be discussed. Fig. 5a. A close relationship usually exists

The vertical distribution of the relevant between the T-S field and the sound velocityvariables near the FLIP site has been empha- structure in the region between the mixed layersized because the density of measured data is and the sound channel axis. For example, inflec-highest at this location. The high concentration tion points indicated by T-S diagrams are oftenof data near the receiver site was intended to reflected in corresponding sound velocity pro-provide ample oceanographic data for acoustic files at equivalent depths. Figure 5 comparesmodeling purposes. A similar program was con- T-S and sound velocity profiles for a CONRADducted during PARKA I (Maury Center for station; both curves show inflection pointsOcean Science, 1969b, and Whalen and others, between 100 and 200 meters. This relationship1971). is not valid at depths below the sound channel

As was indicated in Section 1, only CON- axis, because pressure is the only variable thatRAD carried an STD system capable of mea- normally undergoes significant change in thissuring the variation of both temperature and depth interval.salinity with depth. The velocimeters aboard Initially, the PARKA T-S diagrams wereSANDS and MARYSVILLE sampled tempero- compared with historical T-S plots for the areature and sound velocity; the thermistor chain in order to identify the water masses (Fig. 5a).aboard REXBURG and the XBT's on all ships Comparisons were not made for the surface layermeasured temperature only. Therefore, the because temperature and salinity there are af-discussion of oceanographic variables such as fected by external sources (i.e., temperature andsalinity, density, and stability will be largely salinity are not conservative properties in thislimited to CONRAD data; the salinity structure region). At the northern end of the track theis necessary for the computation of density and intrusion of cold, low-salinity water (apparentlystability. Although CONRAD occupied several of subarctic origin) is evident centered at about

10


SALINITY S%.1 SOUND SPEED (M/SEC)3360 3&*0 34.00 3420 34.40 34.50 34.60 35.00 1470 1440 1490 1500 1610 154O 1530 540 1450 1540 1570

"IS NORTH PACIFIC17 P CENTRAL WATER

15 -t [IS. / /•

/ /4 / 1000

132 CONRAD STD1500 36*0#N 15T*43'W

0505Z 23 NOV691 Z •EPTH 5992 METERS

I I

!2500NORTH PACIFIC *1

-- * "-'IN'TERMEDIATE WATER

7 .16903000

1--

PAC EQ P , T "7' ' 66 l

3500

4

2 CONRAD ST 0 zp0505Z 23• NO 9 li,40

04500

NOTE: NUMBERS ALONG CURVES INDICATE DEPTH

IN METERS 5000

Fig. 5a - Temperature-Salinity Plot for a Fig. 5b - Sound Velocity Profile for a CONRADCONRAD STD Station STD Station

11

II

1


80 meters depth, just below the mixed layer. TEMIRATUo (40

Farther south, this feature disappears. From 0 1 1 1 , ,,I I I ,I.i.IrI.I,330N to 22°N, North Pacific Central Water canbe identified below the mixed layer. Pickard TIMATURE

(i963) states that it may not be advisable to GOO

distinguish between the Eastern and WesternNorth Pacific Central Water Me•sses (Fig. 4), 100osince their T-S properties are quite similar.Consequently, this distinction has not been madein this report. The most obvious feature common IWO - COMAD $TO

to all T-S profiles along the north-south track 27"U'll 1s5.,'WlOI9Z 50EC49

is the North Pacific Intermediate Water Mash. oEPm,seomEmRsPARKA Il-A T-S diagrams indicate its presence am ofrom a depth of several hundred meters down toalmost 1000 meters. The occurrence of the lowsalinity core between 500 and 600 meters at the 2 two0FLIP site (Fig. 5a) agrees closely with Reid x(1965). South of the northernmost station, a .slight increase in salinity of about 0.10°/o, occurs o a,in the low salinity core. Reid attributes this to

vertical exchange with the waters immediately 3W

above and below the core. All T-S profiles indi-cate a gradual transition to Pacific Deep Waterbelow 1000 meters, approaching values of about 4,=o

L.5°C and 34.70%0/.

TEMPERATURE STRUCTUR'E

A typical vertical temperature distribution WO0 -Iin the FLIP area during PARKA II-A is shownin Fig. 6. The surface temperature is slightlymore than 23°C, and essentially isothermal , ,,,conditions exist down to the bottom of the mixed 2a

Fig. 6 - Temperature Structure and Potentiallayer, which oTemperature at the FLIP/SANDS Siteand near-surface conditions are based on datacollected during the final portion of the experi- PARKA I (Maury Center for Ocean Science,ment, and closely resemble the representative I969b, and Smith, 1971b) was thinner, aboutautumn environment in this region. The iso- 40 or 45 meters, and was not as well defined asthermal layer apparent at the FLIP site during in the PARKA 1l-A measurements. This differ-

ence is to be expected, because PARKA I was"*The mixed layer is defined as that layer above the depthat which the temperature is I1C less than the surface conducted in the summer (August and Septem-temperature. ber). The maximum temperature gradient occurs

_- ~12h


below the mixed layer in the region of the salinity profile constructed from a CONRADthermocline, below which temperature de- STD station taken near FLIP (Fig. 7) showscreases fairly uniformly with iacreasing depth. that an isohaline mixed layer extending fromHowever, the thermocline is quite variable, andthe apparent smoothness indicated in Fig. 6 SALINITY

results from the number of data points selected 33 34 35 36

when coding the original trace. The maximum ,depth of the thermocline region is somewhatarbitrarily placed at about 800 meters, belowwhich the temperature profile continues to 500o-

decrease with increasing depth, but much moreslowly, to about 4000 meters. The temperatureincreases between 4000 meters and the bottom 1ooo

(not clearly shown in Fig. 6). This results frompressure effects causing adiabatic heating. Aplot of potential temperature (the temperature 1500

if the effect of adiabatic heating were removed)in water below 1000 meters in depth is includedon Fig. 6. Adiabatic heating causes an increase 2ooo

in water temperature of almost 0.5°C at a depthof 5000 meters, which agrees well with a reportby Latham and others (1969). The temperature zbaooinversion can thus have a significant effect on

the sound velocity structure at depth.

SEA SURFACE TEMPERATURE

The sea surface temperature at the FLIP/SANDS site decreased from 24.2°C to 22.6°C 3500 odiring the 24-day period that SANDS collectedXl3T's during PARKA II-A. During most ofthis rieriod, the mixed layer was approximately 4000

ischicrmal. The depth of the mixed layer wasalmost always less than 100 meters, and aver-aged about 70 to 75 meters. CONRAD STO

27"28'N 157136'W

SALINITY STRUCTURE DETH 5506METERS

The surface salinity in the FLIP area 5000

averaged slightly more than 35.20°/I,. Therelatively high salinity results from an excessof evaporation over precipitation, and according 5500 * I ,

to Jacobs (195 1), is distributed in a broad bandby the prevailing surface currents in the area. A Fig. 7 - Salinity Profile at the FLIP/SANDS Site

13

Ni

S. . ..:. a -t JJ", :' z2;:,••,.:.2


the surface to almost 100 meters is succeeded DENWTY (a,)U4 t5 2 27 to

by an irregular halocline down to the salinity 0 2 ,minimum which occurs around 500 meters.Between 100 and 500 meters the averagesalinity gradient appreaches a maximum nega- 5SO -tive value of 3 x l0-3 0/0 per meter. The salinityminimum represents North Pacific IntermediateWater, which has been investigated in great 1ooodetail by Reid (1965). The salinity of the bottomwater in this area approaches a constant valueof about 34.7000. Iwo - CONRAD ST7 I

At the northern end of the track around 27628'N i5?C36'W10o19 Z 5 DEC 6936°N, the salinity structure is somewhat more DEPT,55O6METERScomplex. The influx of less saline subarctic 2000

water causes a pronounced salinity minimumto occur between 50 and 150 meters it depth.This anomaly is indicated by the bulgWS to the 2500left above 178 meters in the T-S curie shown .in Fig. 5a. The second minimum ,round 525 ameters agrees well with the stati,)n taken near z 300oFLIP, presented in Fig. 7.

SIGMA.T PROFILES

Figure 8 shows the vertical distributionof sigma-t, a quantity closely related to the den- 4000sity of sea water. For comparative purposes,these quantities are often used interchangeably.Sigma-t is defined as: 4500 j

011 =(specific gravity-i) X 103

where the pressure has been reduced to atmo- 5ooospheric pressure, but the temperature and salin-ity are in situ values. The relationship betweensigma-t, salinity, and temperature is rather com- WOOplicated, and it is normally obtained from tables.A comparison of Fig. 8 with historical data Fig. 8 - Sigma-t Profile at the FLIP/SANDS Siteshows the vertical distribution of sigma4 nearFLIP to be typical of middle latitudes. Below depths. This strongly stratified pycnocline indi-the isopycnal (constant density) surface layer cates the high vertical stability (resistance tois a strongly stratified pycnocline, which ap- vertical motion) of water masses in this area. Aproaches a const.-,,., value of 27.80 to great complementary profile of the stability parameter,

14

A


STABILITY (10I E)1o00 0o 50oo 0 OO tOD D000

500-

1000-

1500 CONRAD ST012?Tt2N 5' 65 Wve o'" 57 sos WOI I1Z C1 Z 5DEC 69

DEPTH1 5506 METERS

W2500

3000

3500

4000

4500

I000

5500L . ... I I I I I I J I I1 1 I

Fig. 9 - Stability Profile at the FLIPISANDS Site

E(Z) plotted against depth Z, is shown in Fig. 9, occurs, with conbequent change to the soundusing a relationship for E given by Hesselbcrg velocity structure.and Sverdrup (1915). Negative values of E Figure 9 shows that unstable conditionsrepresent unstable conditions, positive values occur in at least the upper 25 meters at therepresent stable conditions and zero represents FLIP site, and that vertical overturn may occur.neutral conditions. Maximum and minimum Three closely-spa,.ad maxima occur betweenstability values may indicate transition zones 100 and 400 meters, which coincide with thebetween water masses separated vertically, most stable portion of the water column. TheExtreme values may indicate levels where inter- stability maximum at about 370 meters maynal oscillations are most likely to occur. Negative correspond to the transition zone between thestabilities are frequently found in surface layers, North Pacific Central and the North Pacificand often indicate unstable conditions, which Intermediate Water Masses. Below 2500 meters,cannot pei sist for long periods. A readjustment stabilities approach zero but are slightly positive,toward more stable stratification generally indicating a trend toward neutral conditions.

St-


ENVIRONMENTAL VARIABILITY likely that the high wind speeds and large waveheights which were observed during PARKA

The extensive oceanographic program in I[-A could hay,- generated internal wavesPARKA II-A acquired as much environmental sufficient to cause the fluctuations in observeddata as possible spread out along the track of layer depth. Estimates of internal wave fre-the acoustic experiments. One consequence was quency based on the density profile of Fig. 8that the oceanographic data collected during the yield a maximum value of eight cycles per hourexperiment varied considerably in space and (at a depth of 90 meters), and a minimum valuetime. Only on infrequent occasions were two or of 0.92 cycles per day. At this time, the existencemore PARKA ships close enough to each other of internal waves significant to the PARKA II-Ato collect simultaneous data that could be corn- acoustic program is conjectural.pared for quality control. Although all PARKA _

ships passed the FLIP/SANDS site several PCtimes during the course of the experiment, they Part B. T Istor Chain Observationsdeparted the site as soon as possible in order THERMISTOR CHAIN ANDto minimize ship-generated noise at the hydro- ANCILLARY EQUIPMENTphones. Thus, one of the few data records thatcan be examined for evidence of temporal en- Capabilityvironmental variability is the series of XBT's The NURDC thermistor chain measuresthat were collected by SANDS twik.e daily short-period temporal and small-scale spatialduring PARKA II-A. variations in temperature between the sea sur-

The data collected during this 16-day face and a maximum depth of approximatelyperiod at essentially the same location were 220 meters, while operating at its normal towexamined to determir-. the depth of the mixed speed of six knots. Vertical th.-.rmal structurelayer. Figure 10 shows the layer depths plotted is recorded as a function of geographic position

in the form of a time series; these were obtained and time. Forty-seven temperature sensors onfrom the temperature data used to compute the the chain are scanned sequentially (from thesound velocity profiles included in Fig. 42, which surface to the deepest sensor) once every tenwill be liscussed in S-ction IV below. The points seconds. Each scan includes outputs from twohave not bien connected br~cause a significantly calibieating resistors and a depth sensor. At a six-higher samplii.z ,ate woulo have been required Knot tow speed th.. chain data are equivalent tofor true resolution of the curve. However, the a bathythermograph drop every 3 1 meters alongdata plot shows that layer depths ranged at least the ship's track. Each ten-second scan is re-from 56 meters to 88 meters. This variability corded ;n digital form on an incremental mag-c,-uld affect sound transmission in the surface netic tape recorder, and a UNIVAC 1218 con-duct. puter and peripheral equipment are interfaced

The data plottcd ii Fig. 10 show thzt more with the digital system to accomplish real-timethan two observatiris should have been taken data analysis. The real-time program computeseach day in order to resolve the period and the average (equal weight) output from eachamplitude c r the layer depth fluctuations. Never- chain sensor over time intervals that may betheless, it is apparent from the stability profile preset from 3.0 to 94.5 minutes. Hansen (1969)in Fig. 9 that internal oscillations are likely to has described the computer installation andoccur in this shallow depth region. It is also programming in detail.

16

41


A

K 1

S '

Sa

*i ,I•I ll

(S~aRS) HAL


Sensors ment. The th.mrmistor chain was operated con-The 47 thermistors on the chain are spaced tinuously whenever undorway or drifting on the i

PARKA II-A tracks. Temperature data wereat 5.1 meter intcrvals. Temperatures am re . smoothed by averaging over intervals of one

corded to the nearest 0.050C, although the hour. Each average was assigned the time andaccuracy of the measured temperatures is ap-proximately ±- 0. I *C. The sensors are thermally geographic position of the midpoint of the time

lagged and have a response time of 20 seconds. interval over which the average was made. Meansensor depths were computed for earch interval,

The two calibrating resistors show any elec- andeptus were logged for each hourlytronic drift in the system, and the temperature av era the snr d formath hendata are corrected with a slope-intercept formula average in the standard BATH Y format. Whenp coputd fom he alibatin radigsthe chain was not in operation, XBT drops werecnmputed from the calibration readings. made at 0000, 0600, 1200, and I 800Z daily. A

few XBT's were taken while the chain was oper-CONFIGURATION ating, but were discontinued when the XBT

The chain assumes the configuration of a wire fouled the chain. Chain and XBT messagesmodified catenary when under tow. Smith were transmitted to the PARKA Il-A Opera-(1969), in an intensive examination of the chain's tion Control Center. Sea surface temperatures

towing characteristics, empirically derived the were recorded every other hour on the odd hour.

towed configuration. He obtained equations for OMEGA, LORAN A, and celestial observa-

the depth of each thermistor as a function of the tions were used for navigation.maximum depth of the chain. Computed sensor During PARKA II-A, REXBURG towed

the chain along five tracks or runs radiating from~depths are accurate to +-0.5 meter.4da±the FLIP site at 27°35'N, 157°44'W as shownin Fig. I. These are the same tracks used by the

OPERATIONS source ship during the acoustic experiments.

NURDC operational procedures were The tracks and lengths of tow are tabulated inidentical throughout the PARKA il-A Experi- Table I.

TABLE I

Thermistor Chain Tracks in PARKA 1I-A

Event J Chain Tow Track Track Length

9-1 From 220N to FLIP site along 157"44'W 330 nmi9-2 From FLIP site to 31*45'N along 157"44'W 265 nmi

9-3 From 31*45'N to FLIP site along 157644'W 265 nmi

9-4 From FLIP site out on a great circle track bearing 400 nmi247°T from FLIP

9-5 Return to FLIP site following the same great circle 400 nmiroute traveled for Event 9-4


The thermistor chain was also .)p#ratet A ridge like structure centered at 25°Ncontinuously during the time period between the latitude appears in the isotherm contours in theend of Event 9-2 and the Leginning of Lve,,t 9-3, deeper levels. Such a structure could representwhen REXBURG drifted to conserve fuel, ex- sections through thermal domes associated with |cept for a two-hour,,ystem maintenance interval. cyclonic eddies of dimensions comparable toOperations while driftir.n were identical to those those given by Wyrtki (1967). The deeper iso-conducted while underway. therms change depth by as much as 50 meters

The thermistor chain thus furnished many in less than 30 nautical miles horizontal distance,details of the thermal structure in the upper and horizontal temperature gradients as stronglayers of the water column, supplementing the as 5.0 x 10 s°C/m occur. The "ridge" is asym-XBT and STD data which were received from metric, with steeper isotherm slopes accom-discrete geographical locations. Salient features panied by stronger horizontal gradients occurringof the thermistor chain data are described in on its northern side. Vertical displacement ofthe following discussion. isotherms decreases with decreasing depth as a

result of increased vertical mixing toward the

DISCUSSION surface. Smith (197 Ia) reports a similar, thoughmore extensive structure at nearly the same

Isotherm Contour IPlots location in PARKA I. Vertical sections of tern-

Isotherm-depth contours were plotted from perature along 158°W longitude prepared fromthe hourly averaged temperature data for each bathythermograph data recorded during therun and are presented in Figs. II through IS. NORPAC expeditions in 1955 (NORPAC jWhole-degree isotherm depths were obtained by Committee, 191) also show a ridge near 25°N.linear interpolation between adjacent tempera- The presence of these structures in data from

ture sensors on the chain. The vertical axes in PARKA I, PARKA II-A, and NORPAC indi-the plots represent depth in meters, and the cates that they may b,:, a semi-permanent char-horizontal axes are labeled according to time acteristic of the thermal structure north of theand geographic position. The vertical exaggera- Hawaiian Islands.tion of the plots is 1850: 1. Events 9-2 and 9-3 (Runs North of FLIP)

Event 9-1 (From 22°N to FLIP) Temperature data from Events 9-2 and 9-3

Temperature structure recorded during (Figs. 12 and 13) will be considered simulta-Event 9-I is shown in Fig. II. Vertical thermal neously since these runs were made on the samegradients observed on this run are strongest in track. Strong horizontal gradients are presentthe depth interval from 60 to 90 meters. These in the thermal structure in this region. Thesegradients range in magnitude from about 0.1 to occur between about 28°N and 30*N latitude at0.2*C/m. At depths greater than 90 meters, verti- depths of 80 meters and deeper, and range up tocal gradients decrease to approximately 0.02 to approximately 2.5 X 10-*C/m. Similar horizon-0.05*C/rm. Mixed laver depth averages slightly tal gradients were observed in PARKA I (Smith,more than 50 meters, with an approximate range 197 1a). and also are indicated in isotherm con-of between 25 and 70 meters. The temperature tours from NORPAC (NORPAC Committee,of the entire water column sampled by the chain 1960). The NORPAC data show these gradientsdecreases by nearly l.0*C from south to north to extend to a depth of at least 700 meters. Inalong the run. the present data, temperature throughout the

19

OCEANOGRAPHIC ARSULTS

NOATH jAIIUDE I AtONG I 57 44 W)I2)24, 2 S 26 2? 2?'32

20

404

20

% 120I


water column between the surface and 220 mental error. This indicates that this degree ofmeters depth decreases by slightly more than difference in the contours did not observably2°C from the southern to the northern end of the affect propagation.

runs. Events 9-4 and 9-5 (Southwest Runs)Vertical temperature gradients are greatest

at depths from 50 to 90 meters. Gradients in this Vertical temperature gradients recordeddepth interval range in magnitude from approxi. on Events 9-4 and 9-5 (Figs. 14 and 15) aremately 0.1 to 0.2°C/m. At depths greater than strongest at depths from 60 to approximately90 meters, vertical gradients decrease to magni- I 10 meters and range from nearly 0.1 to nearlytudes of from 0.025 to 0.05°C/m. Mixed layer 0.2°C/m. At depths greater than 110 meters,depth varies from slightly more than 40 meters vertical gradients remain within the limits ofto almost 70 meters, with the deeper values gen- 0.03 to 0.1 °C/m. Mixed layer depth varies fromerally occurring toward the southern end of the less than 40 meters to slightly more than 80track. There is always a great deal of microstruc- meters over the length of the runs. The mixedture within the mixed layer, although it is some- layer is generally isothermal, although a smalltimes masked by experimental error. At several area of negative gradients appears at a range oflocations along the PARKA track, the mixed about 325 miles from FLIP on Events 9-4 andlayer is isothermal only to a depth of about 20 9-5. In this region, isothermal water extends onlymeters, then shows a slight decrease in tempera- to a depth of about 15 or 20 meters, and in some

ture over the next 20 or 30 meters. Depending places may disappear completely. Below thison how persistent this temperature change is isothermal layer, the water cools slowly withand how gradually it occurs, it can change the depth. In several isolated cases, the temperaturesign of a sound velocity gradient within the layer at the bottom of the mixed layer (about 80from slightly positive to slightly negative, thus meters) was nearly I°C colder than the near-reducing the effectiveness of acoustic propaga- surface isothermal layer. Acoustic transmissiontion via the surface duct. via the surface duct would be impossible through

Such a situation was observed around any region where this ,egative gradient extended29°40'N on Event 9-2 and 29610'N on Event all the way to the surlace.9-3. Although isotherm contour plots like those There is no appreciable net change in tern-in Figs. 12 and 13 do not clearly show such a perature throughout the water column along .,ephenomenon, a clue to its existence can be seen track, except in the near-surface layer wherein the way the isotherms approach the surface. temperature increases by a little more than 1.0n CIn these two instances, the isotherms approach from FLIP to the end of the track 400 nauticalthe surface at an angle, rather than vertically. miles away. As a consequence, the vertical tem-The mixed layer thus cannot be truly isothermal perature gradient increases slightly with increas-in such a region. ing distance from FLIP.

An apparent southward translation of the Two ridges dominate the profiles from thisthermal structure of about 20 nautical miles from track. These structures are centered at rangesEvent 9-2 to Event 9-3 is evident when the con- from the FLIP site of 100 and 225 nauticaltours are compared. It is important to note, miles. As mentioned above, they may representhowever, that the measured acoustic propagation cross sections through thermal domes associatedloss versus range reported in Volume I was with cyclonic eddies, eddy-associated domes ofidentical for Events 9-2 and 9-3 within experi- this size are not unusual in the Hawaiian Islands

2'i

• - o4

",, , •.•.•n•' :.• .•,• . ...• .• i


r4 ca

40S

C4 C4 C0 CC

ene

z C4

C4. C4 o 40C4 , c

(W N di

U2


DISTANCE ftom FLIP (N MI)

400 300 200 1000

20

40

24 4TIM 20MT

23-

ISO


DISTANCE FROm FLIP (NMI)

20- 24

24 2

2SOV2:2 0 22NO

1224


region (Smith, 1967, and Patzert, 1969). Because oscillatory thermal features of small horizontalno data were recorded transversely to the track extent. Isothermal conditions prevailed in theof Events 9-4 and 9-5, no determination can be mixed layer throughout the runs. However, asmade of the true cause or geographical extent pointed out above, there were several regionsof the ridges. Vertical excursions of isotherms along the PARKA II-A tracks to the north andin the larger ridge (centered 225 nautical miles southwest of FLIP where the mixed layerfrom FLIP) occur throughout the depth range showed a mild negative gradient below a shallowsampled by the chain. Isotherm depth changes isothermal layer. Unfortunately, the configura-in the smaller ridge (centered 100 nautical miles tion, inherent accuracy, and processing schemefrom FLIP) occur only in the lower half of the of the chain system as emplhyed in PARKAchain records. In both structures, depth changes i1-A tended to mask much of this thermalof isotherms decreased with decreasing depth. microstructure.Vertical excursions of isotherms of up to 80 Gross features of the thermal structuremeters in horizontal distances as short as 60 were stationary over the intei As between chainnautical miles accompany the larger ridge. In tows over the same tracks, :-, high variabilitythe smaller ridge, isotherms undergo depth was present in the small scale features havingchanges of as much as 50 meters in horizontal wavelengths less than approximately 25 nauticaldistances of 25 nautical miles. Horizontal miles and vertical amplitudes less than about tengradients within the ridges are as great as 5.0 x meters (compare Events 9-2 and 9-3, Figs. 1210-5°CIm. The larger ridge is asymmetric, with and 13, with Events 9-4 and 9-5, Figs. 14 andstronger horizontal gradients on the side closer 15). These oscillations are superimposed on theto FLIP than on the side away from FLIP. larger scale features and show no correlation

GE A from run to run over the same track.The depth of strongest vertical gradient

No temperature inversions were encoun- and the mixed layer depth vary more in the pro-

tered in the chain data with the smoothing scale files from Events 9-4 and 9-5 than on the otherexployed; however, the incidence of inversions tracks, and the strongest vertical gradient andin temperature records is largely a function of the mixed layer depth average about 10 to 20sampling method and scale (Roden, 1964). At meters deeper on these runs than on any of thethe chain's normal towing speed of six knots the other runs. Even at the maximum depth (220hourly averaging process filters out depth meters) sampled by the chain, there is still anoscillations of isotherms which have wavelengths appreciable vertical temperature gradient whichless than six nautical miles. This averaging meth- indicates that the chain is not long enough tood also eliminates, partially or totally, the non- penetrate the permanent thermocline.

25

*y 4 *

SOUND VELOCITY STRUCTURE

IV. SOUND VELOCITY STRUCTURE methods used in constructing these plots arediscussed below.

As discussed in Section 11 above, thePARKA Il-A area falls largely within the North

Sound velocity in the ocean is usually ex- Pacific Central Water Mass. Therefore, thepressed as a function of three variables: tempera- properties of the near-surface water do notture, salinity, and pressure. Between the surface change greatly out to a range of about 900 nauti-and the depth of the deep sound channel axis cal miles from FLIP (shorter ranges to the

(about 750 meters near FLIP), temperature is south). All of the tracks covered by the variousthe most important variable influencing sound ships in Events 9 and I 1 (Figs. I and 3) fall with-velocity. Below the depth of the sound channel in the region, as do the first 900 nautical miles ofaxis, the cumulative effect of pressure controls the aircraft runs in Event 13 (Fig. 2).

the structure of the sound velocity profile since The sound velocity structure within thistemperature and salinity usually vary little at area is characterized by a deep, well-formed

the" depths. sound channel, with an average axial velocity ofTwo aspectg of the vertical sound velocity 1480 m/sec, and an axial depth of 750 meters.

structure are of major importance in sound The bottom of the sound channel in November

propagation, thc sound velocity and its gradient. and December is at a depth of about 4500The sign of the gradient is a most important meters; bottom topography penetrates into thefeature which is often ignored when the gradient channel on the runs to the east, south, and south-itself is small. The sign, of course, determines west of FLIP (Events 9-1, 9-4,9-5, 13-3, and 13-whether the sound is bent upwards or down- 4). The mixed layer averages between 70 and 80wards and thus is of critical importance in such meters in depth, though it can display consider-regions as the mixed layer and for sonar systems able variability. (See Section 111, Parts A and Bdesigned to exploit that layer as a sound channel. above.) The mixed layer is generally isothermal,The strength of the gradient and the sound veloc- and in most cases shows a slight positive soundity itself determine the severity of bending and velocity gradient, caused by increasing pressure.determine travel times. However, in several locations along the PARKA

Two different presentations will be used Il-A tracks, isothermal water extends only to ato describe these two characteristics of the sound depth of 15 to 20 meters, followed by a weak

velocity structure. The first is a series of shallow negative gradient to the bottom of the mixedand deep profiles of sound velocity as a function layer. In areas where this negative gradientof depth that indicate the strength and sign of the extended all the way to the surface, it wouldgradient at various locations along the PARKA effectively block sound transmission by thetrack. Each profile is plotted at the range from surface duct.FLIP at which the observation was made, and To the north, both the axis and the bottomcarries a ship indicator letter at the bottom of of the sound channel shoal rapidly in the vicinitythe trace. Because of space limitations, no ab- of the water mass boundary between 42°N andsolute values are indicated on the profiles. The 45°N, and the thickness of the mixed layersecond presentation is the standard cross sec- decreases also.tion, showing contours of sound velocity. From To the east the axis of the sound channelthese the velocity of sound at any range and remains deep almost until landfall at San Diego,depth along the track can be determined. The although there is substantial bathymetric inter-

26

A,

SOUND VELOCITY STRUCTURF

ference. In addition, a boundary region near the Figures 19 and 20 are based on the data collectededge of the California Current could change along the southwest track during Events 9-4 andacoustic conditions in that region (about 1300 9-5. The techniques used in constructing thesenautical miles from FLIP). figures will be discussed under Figure Construc-

A comparison of directly-measured and tion below.computed sound velocities shows the computed The deep sound velocity structure alongvalues to be consistently about 0.5 m/sec the PARKA north-sound track from 22°N,greater, below the axis of the deep sound chan- through the FLIP site (27 035'N), to 360N isnel. This discrepancy is attributed to minor inshown by the velocity profiles plotted in Fig.accuracies in Wilson's equation, and is probably 16. The depth of the sound channel axis averagesof little importance in predicting acoustic between 740 and 750 meters, which is in closepropagation. agreement with PARKA I data (Maury Center

for Ocean Science, 1969b). In PARKA I the

PROPAGATION LOSS AND ARRIVAL STRUC- axis remained around 750 meters between 22°N

TURE, SHIP RUNS (EVENTS 9 AND 11) and 31°N, then shoaled to 700 meters at 36°N.Because of a paucity of data north of 32°N, this

Summary latter feature cannot clearly be identified duringThroughout the region covered by ship PARKA Il-A, although several CONRAD pro-

runs during PARKA Il-A, a well-formed sound files seem to indicate such behavior.channel prevails, with an average axial depth of The maximum sound velocity above theabout 750 meters and an average axial velocity axis is generally located in the mixed layer. Theof about 1480 m/sec (±t I m/sec). The mixed bottom of the sound channel, that depth at whichlayer averages between 70 and 80 meters in the surface (or near-surface) sound velocitydepth, producing a weak surface duct in this maximum recurs below the axis (also calledarea during the autumn season. Occasionally, critical depth), occurs around 4500 meters.the usual weakly-positive gradients in the sur- Where the water depth is 5500 meters, this re-face layer are interspersed with profiles dis- suits in a "depth excess" of about 1000 meters,playing slightly negative gradients. These would which provides for reliable convergence zonehave the effect of interrupting propagation via propagation. As shown in the bathymetric pro-the surface duct. The greatest variations in sound file of the north-south track from 22°N to 36°Nvelocity in each profile occur in the interval (Fig. 18), such a depth excess prevails on thebetween the bottom of the mixed layer and the track north of FLIP. The track to the south to-sound channel axis. ward Oahu is severely bottom limited, however,

Figures 16, 17, 19, and 20 display all the by shoaling of the average depth to about 4500deep velocimeter and STD data collected along meters, and by several seamounts rising abovethe PARKA Il-A ship tracks (Figs. I and 3), the critical depth. These intrude into the bottomregardless of the time during the experiment third of the sound channel, and can be expectedwhen the observation was made. Data shallower to degrade acoustic propagation severely on thisthan 1000 meters were eliminated from these leg.illustrations to avoid overplotting near the sur- The sound velocity gradient is normallyface. Figures 16 and 17 cover the north-south quite stable in the deep ocean below the axis oftrack from 22°N to 36°N, and include all deep the sound channel. From Fig. 16, the gradientdata from Events 9-1, 9-2, 9-3, 11 -1, and 11-2. is determined to be 0.0176 sec-1. This agrees

27


closely with 0.0 178 sec- 1, the gradient predicted as Figs. 16 and 19) and contoured cross sectionsby Wilson's equation (Wilson, 1960) when only (as in Figs. 17 and 20). These illustrations arethe effect of pressure is considered. The nega- based only on the somewhat sparse deep obser-tive gradient above the sound channel axis is vations, and nearly all the available data wereconsiderably steeper than the deep gradient, and plotted. When confronted with high data densityis much more variable. (as in the figures for shallow depths discussed

Figure 17 displays in contoured form the below) the method used in plotting the data be-velocity profile data of Fig. 16. The sound veloc- comes important, since some data must arbitrar-ity contours (isotachs) were drawn for a contour ily be eliminated to insure the legibility of whatinterval of 5 m/sec. The axial velocity of slightly remains.more than 1480 m/sec over the length of the The following discussion describes thetrack is not specifically contoured. Surface techniques used in plotting the profiles and con-velocity decreases from 1534 rn/sec: at 22*N tehiussdinpoigteprflsadc-(-330lnautityecrales) tom 15 rn/sec at 2°N toured cross sections shown in this volume.(--330 nautical miles) to 1511 m/sec at 36°N ,

(510 nautical miles), with most of the decreaseoccurring in the transition zone north of 32°N(265 nautical miles). This decrease in sound 1. Sound Velocity Profilesvelocity is caused by the influence of cooler Tnorthern water. Because of the vertical scale The shallow sound velocity structure inemployed here, little detailed structure is evi- the PARKA area from the surface to a depth of

dent, particularly near the surface, but the uni- 750 meters is shown by six shallow sound Iformity of the deep ocean environment is clearly velocity profile plots (Fig. 22, 23, 24, 28, 29,

indicated, and 32), one for each acoustic event (Events 9-1,The sound velocity structure along the 9-2, 9-3, 9-4, 9-5, and one for both 11-1 and

400 nautical mile track southwest of FLIP 11-2). Each profile includes oceanographic data(Events 9-4 and 9-5) is shown in Figs. 19 and 20. collected only during the time the particular

The deep axial sound velocity, depth of axis, and acoustic experiment was being conducted. The Iýhe gradients above and below the axis are shallow profiles extend to a depth of only 750imilar to those north and south of FLIP dis- meters, because not enough deeper data were

cussed above (Figs. 16 and 17). The bathymetric collected during the two and one-half to threeprofile for this track is displayed in Fig. 21. day duration of each run to justify extendingSt: Ling at a range of about 150 nautical miles the scale any deeper. Most of the shallow pro-

from FLIP, this track encounters very rough files are constructed from XBT's, which termi-ain, with a seamount rising over 2000 meters nate at this depth. These plots permit a detailed

from the ocean floor at a range of 225 nautical analysis of the near-surface environment, wheremiles from FLIP. Other seamounts on both sides the sound velocity structure is most variable.of the track also intrude into the sound channel, Nearly all of the profiles were computed byinterfering with acouitic propagation through- FNWC using measured temperature data fromout the area. XBT's, AXBT's, and the thermistor chain,

combined with archival salinity data. A fewFigure Construction MARYSVILLE profiles are based on shallow

The prominent characteristics of the sound measurements of sound velocity obtained withvelocity structure are shown in profiles (such a velocimeter.

28

-390 -360 -330 -300 -270 -240 -210 -180 -150 -120 -900

20NN

500-

1000

1500-

2000-r 2500

3000

3500-

4000-

4500 I5000C

-390 -360 -3w0 -300 -270 -240 -210 -leO -150 -120 -90

14-~ ~ - ~-MONK- -

II

-90 -60 -30 0 30 60 90 120 150 180 210

1. Nominal FLIP position: 27035'N,157*2. Observations are plotted at actual rani-

(Negative ranges are south of FLIP,3. Includes all deep data collected during4. Letter at bottom of profile indicates,

C - CONRAD

M = MARYSVILLE iS - SANDS

I

-120 -90 -60 -30 0 30 60 90 120 150 ISO 210RANJGE FROM FLIP (NAUTICAL MILES)

Fig. 16 - Deep Sound Velocity Profiles Along PARKA 11-A North-South Track (157 44,W)

29

(Page 30 Blank)

42-

180 210 240 270 300 330 360 390 420 450 480 510

336

FLIP position: 27 035'N,1570 44'W 6

atlons are plotted at actual range from FLIP along top scale"ve ranges are south of FLIP, positive ranges are north of FLIP)

Iall deep data collected during Events 9-1, 9-2, 9-3, 11-1 and 11-2st bottom of profile indicates source of data:

S-' CONRAD- MARYSVILLE, SANDS

20 M/SEC

SI i

I i

II V

180 210 240 270 300 330 360 390 420 450 480 510

157°44'W)

S1"A

270 300 330 360 390 420 450 480 5310 540

157 43W

k FLIP along top scalennges are north of FLIP)ý 9.1, 9-2, 9-3, 11-1 and 11-2Of data:

2:i20 M/SEC -

:I 1 " .,

270 300 330 360 390 420 450 480 510 540

A"

ri

L -. *

RANGE FROM FLIP (NAUTICA 1

-SOUTH N^MINAL FLIP POSITIO 2TO35N, 15744'W

-330 -300 -270 -240 -210 -180 -15O -120 -90 -60 -03 0 9 20- - -.... 1 1 1 a

WO f -lot I 1Ai t~%a

o 1405 .........-- ------------------1490-------------------------------------_ _ _ _ _ _

3000-2500

4.__000-__ __ __........

43500- l .... '

3500 0 s'S

45000 s'

Fig. 17 - Contoured Deep Cron Section of Sound Velocity A1o04

RANGE FROM FLIP (NAUTrCA1J1 6srus 15705O1W a?**" 'w oW:OT-S00 -Lam -100 100

~0 ... . . . . . ....................................................... . . ........ ..

3000 --

4000•

2OOF s r lý ............

I III _mooo

Fig. 18 - Bathymetric Profile, PARKM

31(Page 32 Blank)

~~ *j..w

�NGE FROM FLIP (NAUTICAL MILES)�'N 5?44'W NORTH -�

10 60 90 120 150 ISO 210 240 270 300 350 360 390 420 450 480 510ppj p p I I -0------------------------------------------------------------------------------------�:��so

___________________________________ ------------- * - - ------------------ 500________

LEGEND

STATION LOCATIONS 1000SSPARSE DATA

---------------------------------------------------------------------------------------------------------------------------- 465 1500 ]-- -- '�'� 2000�j!

---------------------------------------------------------------------------------- '4,5 2500---------------- ------------------- 1500

------------------------------------------------------------------------------------------------------------------------- - '� 3000-----------------------------------------------------------------------------------------------is to

----------------------------------------------------------------------------------------------------------__________________________________ -- ISIS �

--------------------------------------------------------------------------------------------------------------------------------- 1520 4000---------------------------------------- - -------------------------------------------------------------------------- I�25 I-------------------------------530

--------------------------------------------------------------------------------------------------------------------------------------------- 1535 4500S1540 -5000

of Sound Velocity Along PARKA H-A North-South Track (1570 44W)

RANSE FROM FLIP (NAUTICAL MILES)PWw, IS?60W WOO'N IS?'OW

6 �o zoo uoo 400

CAuft AXES INOTES'

I. DEPTHS 944E KEN CORRECTED FORVARIATIONS SI SOUND VELOCITY

3. NESATIVE RADIUS ARE SOUTH OF PUP,POSITIVE RANKS ARE NORTH CF PUP

U SATHYMETRIC PRULE AIW ON DATACOLLECTS SY RN CONRAD GURINSPARKA I, SOS.

...............................................................................

*etroM o� II SOU��D CHAN

Bathymetric Profile, PARKA North-South Track

31(Page 32 Blank)

k -�i7TT�

540 510 480 450 420 390 360 Z30 300 270'0 -~~~'~~2432'NI 1

165* 21' W

500-

2000-

2500-

3000 20 M/SEC

1. Nominal FLIP position. 270 35'N,1570 441 W4(~00 2. Observations are plotted at actual range from FLIP along top 5"~

3. Includes all deep data collected during Events 9-4 and 9-64. Letter at bottom of profile indicates source of data:

4500[ C - CONRADM - MARYSVILLES - SANDS

500 1 F.. L.. . .-. 4...-. - ...- L -.. 1500 540 510 480 OF0 420 390 360 330 300 27C

Fig. 19 - Deep Soum

300 270 240 210 ISO 150 120 90 60 30 0 -30

2703V' N

15?* 37'W

I "

.1

FLIP along top scaleýs 9-4 and 9-5of data:

300 270 240 210 ISO 150 12C 90 60 30 0-3RANGE FROM FLIP (NAUTICAL MILES)

rig. 19 - Deep Sound Velocity Profiles Along PARKA II-A Southwest Track

33

(Page 34 Blank)

ISO 150 120 90 60 30 0 -30 -60 -90 -too

I) l I

M 0 150 120 90 60 30 0 -30 -60 -90 -120. A M 1LwS)

•KA II-A Southwest Track


-~ (SU313ni) Hd3O.,,...... ............. I .... I II I I I I ..... ...

into00.-N

IL-

___ll

- (

- g%

il

I

i-ii I

It I

(2 !2 In

in to in

(SM33W)HI14 N I 35


24036'N,16S21'W RANKE FROM FLIP (NAUTICAL MILES) 2739N,I5?*44'W

400 300 200 100 60

. ...........................so..H. ...c.• ..• g . !.s.. .....................................................

1000-

NOTES1I. DEPTHS HAVE BEEN CORRECTED FOR

2000 VARIATIONS IN SOUND VELOCITY

2. BATHYMETRIC PROFILE BASED ON DATACOLLECTED BY RV CONRAD DURINGPARKA n-A, 1969.

wI-000W

~.4000 1S............... .--. --------- .... .. .. ..... .r

5000

6000

7000 I I

Fig. 21 - Bathymetric Profile, PARKA II-A Southwest Track

2. Contoured Cross Sections of MARYSVILLE velocimeter), with shallow dataSound Velocity (REXBURG thermistor chain, or XBT's from

A series of six shallow cross sections of any ship) used to fill in the blank spaces.sound velocity have been plotted for the same Stations from the various PARKA ships

acoustic events and are based on the same data were plotted in the following order: CONRAD,as the profiles discussed above. These were SANDS, MARYSVILLE, REXBURG. The

constructed by contouring machine-plotted plotting program did not permit two stations to

sound velocity values as a function of depth be plotted in the same location; consequently,

and range from FLIP. The paper size, height and the deeper observations from the first ship tookwidth of numbers, etc., required the deletion of precedence over the shallower information from

some observations to prevent overplotting. the others. As SANDS stayed in essentially theThe individual stations were computer- same location during the entire experiment,

sorted by ship, depth, and time of observation. only one or two of her stations were included.Each plot, therefore, includes only the environ- The contour interval is 5 m/sec. The plotsmental data collected during the particular used to construct these cross sections wereacoustic event. Preference in plotting was given machine-printed with no more than one stationto deep data (e.g., CONRAD STD, SANDS and every two nautical miles in the horizontal, and

36


one data point every seven meters in the verti- from 22°N to 36°N, from the surface to a depthcal. Consequently, the smallest feature that can of 750 meters. TIis depth approximately marksbe shown is about four miles wide by fourteen the base of the permanent thermocline, whichmeters deep. Ranges from FLIP are shown in coincides with the axis of the deep soundnautical miles. channel. Figure 22 includes all observations

The series of 750-meter illustrations covers made during Event 9-I, from 22°N to FLIPthe water column above the axis of the sound (at 27°35'N). Figure 23 shows profiles collectedchannel. This region typically displays the during Event 9-2 from FLIP north to 36°N,largest fluctuations in velocity structure. The and Fig. 24 shows profiles collected during Eventcross sections are a static presentation of a 9-3 from 36°N south to FLIP. Each profile isdynamic medium, and are influenced by the plotted at the appropriate range from FLIP andsampling method and contour interval. Although carries a ship indicator letter at the bottom ofthe data points were plotted along the track to the trace.facilitate contouring, they are not in chronolog- These sound velocity profiles display vary-ical order. Therefore, some of the perturbations ing degrees of detail caused by differences inshown by the isotachs may be caused by changes the vertical sampling intervals used aboardin the near-surface sound velocity structure different ships. Considerable detail is evidentduring the time that elapsed between the occupa- in the 220-meter profiles computed from tem-tion of adjacent stations. This may also partially perature data collected by the NURDC thermis-account for the noticeable lack of agreement tor chain aboard REXBURG. The consistentlybetween these contours and those constructed negative gradients between the mixed layer andfrom the N U RDC thermistor chain temperature about 700 to 800 meters are typical of themeasurements in Section 111, Part B. Each event thermocline region where temperature is thecovers between two and a half and three days, controlling factor. This region forms the upperand considerable variability in the near-surface portion of the deep sound channel.environment may occur over such a period. The The mixed layer (in agreement with tem-different methods of data collection and coding perature observations) extends from the surfacemay also introduce minor perturbations of the to depths of 70 to 80 meters, both north andisotachs. south of FLIP. A comparison of the profiles

shown in these three figures indicates that thereis very little difference in the sound velocity

Shallow Sound Velocity Structure North gradient over the length of the north-southand South of FLIP (Events 9-1, 9-2, and 9-3) track. A slight positive sound velocity gradient

As has been stated, the depth interval appears in the mixed layer in most of the profiles,between the surface and the axis of the deep regardless of their location on the track. Assound channel displays more variability than isothermal conditions usually prevail in thisany other part of the water column. In addition, layer, this slight positive gradient results fromthe characteristics of the sound velocity struc- increasing pressure. The positive gradient pro-ture in this depth region are particularly impor- duces upward refraction of sound and can leadtant since in most situations the source and/or to repeated surface reflections for a source inreceiver lie within the domain. Figures 22 this layer. Any perturbations in the depth of thethrough 24 display the gross sound velocity mixed layer will tend to distort the cyclic sym-conditions along the north-south PARKA track metry of this mode of propagation.

37A


In a few cases, slightly negative gradients water mass, which is similar to the subarcticexist within the mixed layer. This situation can water found farther north, forms only the upper-best be observed at approximately 100 to 150 most part of the water column (Roden, 1970).nautical miles north of FLIP (Figs. 23 and 24). Roden also suggests that the persistence of thisA change in gradient of this type frequently re- shallow water mass is accounted for principallyflects spatial or temporal fluctuations of the by winds and air/sea energy exchange. Con-medium. Such perturbations in the velocity sequently, this noticeable change in sound veloc-structure within the mixed layer can have a ity is restricted to the upper layers of the watersignificant effect upon sound transmission both colum. Below a depth of about 250 meters, thewithin and below the layer. When both sound nearly horizontal and parallel isotachs predomi-

source and receiver are located within the layer, nate over all other features that occur alonga negative gradient will produce the classic the tracks (see also Fig. 17).shadow zone phenomenon. Thus, the existence Figures 26 and 27 depict the sound veloc-of isolated reversals in gradient within the layer ity conditions along the same track but differingindicates that the character of sound refraction in time by about three days. Comparison of theseobserved in this region may be particularly sen- two illustrations shows that, although verysitive to the depth of the source, and that trans- similar, the two figures are not identical, evenmission via Zhe surface duct may be unreliable below 500 meters. Because of the arbitraryor impossible. method of construction, these contour plots do

Figures 25 through 27 display contoured not depict the environment precisely, thoughcross sections of the same data included in Figs. they can reveal the type and the magnitude of22 through 24 above. Figure 25 includes data perturbations to be expected. The irregularitiesfrom Event 9-1, Fig. 26 from Event 9-2, and present here suggest time-dependent fluctuationsFig. 27 from Event 9-3. These cross sections of the medium. As noted in Volume I of thisindicate the non-isothermal character of the report, the changes in contours between Eventmixed layer at a range of about 100 to 150 nauti- 9-2 and 9-3 did not result in observable differ-cal miles north of FLIP (Figs. 26 and 27). The ences in the measured acoustic propagationexistence of such pockets or tongues of warmer loss.

(higher velocity) water in the mixed layer prob- Above the depth of the permanent thermo-ably caused the appearance of the negative sound cline, temperature is the major factor in deter-velocity gradients observed in this same area mining sound velocity. The steepest sound i

on Figs. 23 and 24. It is very likely, therefore, velocity gradient shown in Figs. 25 through 27that propagation via the surface duct would be is located at a depth of 60 to 90 meters, andinterrupted through this area. coincides with the strongest temperature gradi-

The surface sound velocity along the track ent displayed in the temperature cross sectionssouth of FLIP (Fig. 25) averages about 1534.0 in Figs. 11 through 15 in Section 111, Part B.rm/sec. North of FLIP, (Figs. 26 and 27), a de-crease in the surface sound velocity of over 20 Shallow Sound Velocity Structure Southwest

nm/sec occurs over the 500 nautical miles be- of FLIP (Events 9-4 and 9-A)tween FLIP and the northern end of the track, Events 9-4 and 9-5 were conducted inwith most of the change occurring between 32°N opposite directions along a 400-nautical mileand 36°N. This trend reflects the transition zone great circle track on a bearing of 247°T fromnorth of 32°N. However, this transition zone FLIP. The shallow sound velocity profiles show

38

1. Nom2. Obse3. Lette,

I390 360 330 300 270 240 210 ISO 15C 120 800 22*02'N

157* 4VW

75-1

150-

300

450

525 A

d00 I

7539 360 330 300 270 240 210 ISO 150 120 SORANGE FROMJ FLIP (NAUTICAL MILES)

Fig. 22 - Shallow Sound Velocity Profiles, Event 9-1 (Propagation Low and Arrival Structure), 2

39(Page 40 Blank)

1. Notiiinal FLIP position: 27035 'N,157044'W

2. Observations are plotted at actual range from FLIP along top scale63. Letter at bottomn of profile indicates source of data:

C a CONRADM - MARYSVILLER - REXBURGS -SANDSP - PARKA AXBT

240 210 IS0 150 120 s0 60 30 0 -30 -60

'--271- 36-N

157*514

F -

24 20IS 5010 o603 0-0/6RAG RMFIP 1NUIALMLSund eloityProfles Evnt 91 (ropgaton Lu ad Ariva Stuctre),22* toFLII3

(Pg 0Bak

-60 -30 0 30 so 90 120 150 I80 210 240

157* 42'W75 -

150

225-

300

-375I-za.

450/

525 20M/E

675-

7... -30 0 30 60 90 120 150 ISO 210 240RANGE FROM FLIP (NAUT 9

Fig. 23 - Shallow Sound Velocity Profiles, Event 9-2 (Propa atL

41(Page 42 Blankq

A

1. Nominal FlAP poaPluon: 27*35'N,1570 44'W2. Observations are plotted at actual range from FLIP along top3. Lutter at bottom of profile indicates source of data:

C - CONRADM - MARYSVILLER - REXBURG8 - SANDS

210 240 270 300 330 360 390 420 450 480 5105r'oo6 00*1.

157' 4'5'W

I

1rr

/ "//- I )

210 240 270 300 330 360 390 420 450 480 510RANGE FROM FLIP (NAUTICAL MILES)

ty Profiles, Event 9-2 (Propagation Loss and Arrival Structure), FLIP to 36eN

41(Page 42 Blank)

--

/ *

I

60 .30 0 30 60 90 120 150 ISO 210 240

187"41'W

151.57 1 I

375I

450 I

I io

525 /

675 =1I

-30 0 30 60 90 120 150 ISO2124RANGE FROM FLIP (NAUA.

Fig. 24 - Shallow Sound Velocity Profiles, Event 9-3 (Prop•--

43(Page 44 Blank).

- I~u

1. Nominal FLIP position: 27*35'N,1570 44'W2. Observations are plotted at actual range from FLIP along top scale3. Letter at bottom of profile indicates source of data:

C - CONRADM - MARYSVILLER - REXBURGS " SANDSP - PARKA AXBT

240 2"0 300 330 360 390 420 450 480 540 540

35' 44'NI1?7041,W

74

SN-------

240 270 300 330 360 390 420 450 480 510 540FROM FLIP (NAUTICAL MILES)

Event 9-3 (Propagation Lou and Arrival Structure), 360 N to FLIP

43(Page 44 Blank)

S~ --

RANGE FROM FLIP (NAUTICALNORTH - -4

330 300 270 24020 SIOI

753

225- 7L ------------

-SI--- - ----- - - --- - - - -

W 300 lOSI, - - - - - - - - - - - - -- - -%-- - - - - - - - -- - - - - - - - - - - - - -

w3375-

125435 -- ---- -----------------------------

6w- LEGENDTr-r - STATION LOCATIONS

1600-.--SPARSIE DATA

Fig. 25 - Contoured Shallow Croes Section of Sound Velocity,

45

(Page 40 Blanki

GE FROM FLIP (NAUTICAL MILES) NM~LFI OIIN-73',1?4'

150 120 90 60 10l~-0

13o 75!

-15

405 30 a.

6375

-450 a

145

(Page 46 Blank)

NOMINAL FLIP POSITI 2?-35'N. 157044W NORT 90---- 150 ISO03

150- 1520

I -

w 30

6 0 0 0-

375- 149

450- 19

w~525-

600

6.....................................††††††††††††††††††††††††††††††††††††-'

- ~ ~4

RANGE FROM FLIP (NAUTICAL MILES)

180 210 240 270 30 33

----------

F.

---------------------------------------- --------------------- -------------------- -------------

--- -- --- -- --- -- --- -- -- --- -------------------- - ---------------------... .-.-- _

- - - - - - - - -- - - - - - - - - - - - - - - - -- - ----- - - - - - - -

-- - - - - - - - - - - - - - - - - - - - - -------------------------------

----------------------------------------------------------------------------------

LEGEND

IT••-." . .STATION LOCATIONS- . .,

--- -SPARSE DATrA-

Fig. 26 - Contoured Shallow Cross Section of Sound Velocity, Event 9-2 (Propagation Loss and Arrival Structure), FLIP to 36N

-I

47

(Page 48 Blank)

II

30390 420 450 480 5,10.I 0

-- - --- - -- - - -- - -- - - -- - - ---- s~ 150 -75

• -------- :; - : = :- - - -- - ---- . . . . . . . . .- ---'• • ; '-.. . .- . . . . . . .-'-- . .

----"-- - -250

....- 149 225

.. ...-4o -375 I;" . ... . . ... .. ,115 -450

525

---------------------------------------------------

----------------------------------------------------------------------------------- 60. .. "14610

-750

"cture), FLIP to 36 0 N

I

"I

- ... . - - - . .~~ ~ k. t ."

NOMINAL FLIP POSITI N 2735N,I5?*44W 3060 90 120 150

75 1'%3052

50 15201510

2245- 50 -----

600

6751- 7501 IAI

RANGE FROM FLIP (NAUTICAL MILES)NORTH -

150 210 240 270 300 330

- - ------- I ..- -- -

-- ------- ---- --- -- --------------------------------------------- - - -- -- -- - --- - --- -- -- -- -- - - - -

*- -- - --- - -- - - - - - - - - --------- - - - - - - -

Tr--T- SATONLOCATIONS

SPARSE DATA j

Fig. 27 - Contoured Shallow Cross Section of Sound Velocity, Event 9-3 (Propagation Loss and Arrival Structure), 36ON to

49

(Page 50 Blank)

"g' _g

i'1

1r

330 360 390 420 450 480 51O

!I. I '/0

--------- ISM5--1

S-------------------------- -150

~------- --------------- .3w9. 40 -:375 3 "I-

-... • 450 a

-.... 525

------- 14W, -600

- , " "S.........-- - 750

val Structure), 36WN to FLIP

on

.I

i


that isovelocity or near-isovelocity conditions LONG RANGE PROPAGATION LOSS,prevail in the mixed layer, except where the AIRCRAFIr RUNS (EVENT 13)mixed layer de,•pens at a point about 320 nauti-cal miles southwest of FLIP (Fig. 28 for Event Summary9-4 and Fig. 29 for Event 9-5). The gradientsdisplayed in these profiles are similar to those During Event 13 aircraft dropped explo-along the north-south track (Figs. 22, 23, and sive charges for propagation loss studies along24). A slight sound velocity minimum appears five runs on three long-range tracks radiatingin several profiles at a depth of about 75 meters from FLIP (Fig. 2). The tracks to Adak (Eventson both runs along the southwest track. This 13-1 and 13-2) and San Diego (Events 13-3 andminimum produces a secondary sound channel 13-4) were completed in both directions, withwhich could enchance detection of a target in charges dropped inbound and outbound, butthe layer, although the effect would be restricted AXBT's dropped inbound to FLIP only. Theto short ranges at isolatee 1ocnv run along the PARKA I track due north to 55°N

Figures 30 and 3 ,,isp i,' coitoured cross was completed using charges only (Event 13-5).sections of the same data r!tJhded in Figs. 28 The return trip plus a planned round trip toand 29. These vait• s are suwnlar to those con- Seattle were eliminated after FLIP was disabledtoured in ig. 25 for the track from Oahu to on 1 December. Because of equipment failuresFLIP. The figures for the southwest track show and other problems, environmental data in the

virtually parallel and almost horizontal isotachs form of good AXBT traces were collected towith no surfacing of the near-surface contours only Hmited ranges on Events 13-1 and 13-3.except near maximum range, beyond 350 nauti- Figures 34 and 35 show sound velocity profilescal miles. In this area, the isotachs indicate a along these tracks constructed from the PARKA I

confused velocity structure in the mixed layer, AXBT data combined with archival salinitywith possible interruptions of the surface duct. information. In order to describe the soundAlthough the layer is apparently not isothermal velocity conditions along the entire length ofin this region, no negative gradients are apparent all of the acoustic runs, some supplementaryon the near-surface portion of the profiles given profiles have been constructed. Figures 36in Figs. 28 and 29. through 39 display a series of sound velocity

profiles computed by FNWC from archivalNansen cast data for the four Event 13 tracks.

Shallow Sound Velocity Structure North Bathymetric profiles collected by the PARKAof MAHI (Events 11-1 and 11-2) ships prior to the experiment are also shown on

these figures.Figures 32 and 33 show all data collected The ocean environment on the tracks

during both Events 11-1 and 11-2, and are in- radiating northward from FLIP to Alaska (Figs.cluded primarily for record. After FLIP had 36 and 37) is characterized by a deep soundbeen disabled, these acoustic runs were carried channel that shoals rapidly in the vicinity of theout on a north-south track utilizing MAHI as Subarctic Convergence (about 42°N). Thethe receiving ship. The profiles and the corre- critical depth decreases rather uniformly fromsponding contoured cross section are based on FLIP northward to Alaska.few observations, and provide little new infornia- In contrast, the axis of the sound channeltion concerning the sound velocity structure. remains relatively deep on the track eastward to

51


San Diego (Fig. 38). However, sound velocity the Alaskan coast, the axis shoals gradually toconditions do not remain constant along the about 100 meters (55 fathoms) near the northernentire track. In the vicinity of the California end of the tracks. As shown in Figs. 36 and 37,Current a marked boundary region exists be- the critical depth drops to less than 600 meterstween two water masses (Fig. 4) at about 1300 (330 fathoms) off AI-ska, which is just below thenautical miles range. Propagation loss measured axis. With depth excess increasing from 1000at FLIP should generally increase with range meters at FLIP to 4200 meters off the Alaskanuntil this transition zone is reached, where coast, convergence zone propagation is unim-significant perturbations may occur. Partial peded over the length of both of these tracks.interruption of acoustic p-.opgation by seamounts The Mid-Pacific Transition Zone is char-and other complex bathymetry is possible every- acterized by near-surface instabilities and awhere on this track from a range of 500 nautical complex vertical structure in the upper severalmiles to the coast of California. hundred meters of the water column. Farther

north a characteristic vertical temperature struc-ture prevails over most of the Subarctic Pacific

Adak avd Due North Aircraft Runs region. This structure (termed "dichothermal"(Events 13-1, 13-2, and 13-5) by Uda, 1963) is characterized by a temperature

minimum at a depth of about 100 meters, andThe oceanographic features and the sound can be formed in two ways. First, just north of

velocity structure along the Adak and "due the Subarctic Convergence, warmer subsurfacenorth" runs are similar and will be considered water of tropical origin may intrude into thetogether. N,)rth-northwestward from FLIP there subarctic water mass, resulting in a temperatureis a typical substropical sound velocity struc- minimum immediately above the intrusionture which extends to about 32°N (Figs. 36 and (about 100 meters), and a temperature maximum37). It consists of a well-defined deep sound at the depth of the iW ision. Water associatedchannel with an average axial depth of 750 with this temperature maximum is called "meso-meters (410 fathoms). Between 32°N and 42°N, thermal" by Uda when found in the subarcticthe Mid-Pacific Transition Zone is encountered. region. Second, a similar temperature structureThis zone couples a deep, 750-meter sound found to the north-northwest is probably causedchannel having a large velocity difference to the by seasonal heating effects.south with a much shallower, 200-meter sub- The dichothermal/mesothermal structurearctic sound channel having a considerably accounts in part for the shallow sound channelsmaller difference to the north. Much of this found in the area described above. The strengthchange in the character of the sound channel of the channel and- the critical depth (bottomapparently takes place near the northern edge of the channel) should be seasonally dependent.of this transition zone, near 42°N. As indicated Increased surface temperature in summer andearlier in this Section, the bottom of the sound the associated near-surface negative gradientchannel at the FLIP site occurs at about 4500 intensifies the sound channel; in winter the sur-meters (2460 fathoms); at 50°N it occurs around face layer becomes isothermal, and as the near-500 meters (270 fathoms). Although the critical surface temperature maximum decreases, thedepth decreases gradually with increasing critical depth becomes shallower, and thelatitude from FLIP, it also shows a sharp de- maximum velocity difference decreases. Re-crease around 42°N. From 42°N northward to gardless of seasonal changes, topography does

52

..... .. ..

540 510 460 450 420 390 360 330 300 270 240

0 ~240 37'N165012W

75-

150

225-

300

S375 -

I-'450

20MISEC

525

675-

7501 O 480 450 4210 390 340 3i 4,540 510 RANGE FROM FLIP (NAUTICAL MILES

Fig. 28 - Shallow Sound Velocity Profiles, Event 9-4 (Propagation Lou an-

53

(Page 54 Blank)

A1. Nominal FLIP position: 27*35'N,157°44'W2. Observations are plotted at actual range from FLIP along top scale3. Letter at bottom of profile indicates source of data:

C CONRADM. MARYSVILLER -REXBURG8 - SANDS

270 240 210 ISO 150 120 90 60 30 0 -30

27-36'N1576 37,w

I I_

L#/

I

240 210 ISO 150 120 90 60 30 0 -30FROM FLIP (NAUTICAL MILES)

9-4 (Propagation Loss and Arrival Structure), from FLIP to about 24030N.165020'W

53

(Pagb 54 Blank)

660 540 510 480 450 420 390 360 330 300 2700

25s00' N164* I1'W

150

225

300-

~375

450-

20 M/sEC525

800-

675-

660 540 510 460 450 420 390 360w 0RANGE FROM FLIP (NAUTICAL

Fig. 29 -Shallow Bound Velocity Profiles, ."vent 9-5 (Propagation Lons andl

(Page 56 Blank)'

1. Nominal FLIP position: 27•0 35'N,157a44'W2. Observations an plotted at actual range from FLIP along top scale3. Letter at bottom of profile indicates source of data:

C - CONRADM - MARYSVILLEIt - REXBURGS - SANDS

k300 270 240 210 ISO ISO 120 90 GO 30 0 -30

I

,N

300 270 240 210 ISO ISO 120 90 60 30 0 -30


t 9-5 (Propagation Lou and Arrival Structure), from about 24 0 30'N,165020'W to FLIP

55(Page 56 Blank)

le-, , d- w 2I>iL ",

iw.

4?0 420

75- --- - - - - - - - - -

I----------12 5 ------------------------

15o 0 -----------------------

375-2 Z- .225 1506 "------ --.... --.....

600---------------------------------------------------------------------------

375.S.................

Gm ------------ -------------- -- - -"

Fig. So - Contoured Shallow CronE Ii I I~ i I I ~ i I~ i lI l

I I ~ ~ I ~ I l~ li lil l l l IIIi

I7-

RANGE FROM FLIP (NAU'sICAL MILES)

2?0 240 210 10 150 120 so1w 1 20 1 1 1 1 1~ 1 11 1 I I IIr- I II a, - -

II I I 1 1

~5iz~---- -- -- ----

- ---- ----- - --

Kp ------------ L EGEN ODI1r---r-STATION LOATIONS~

wCrow Section of Sound Velocity, vn -.oato o and Arlrial Structure), from FLIP to about 24 3O'N,1650 20'W

57I'> (Page 58 Blank)

NOMAINAL FLIP POSITIO 27*35 N IS?44,w

120 90 60 30 1 0

1550 -75

1520 -50isle

1510 -2

_____ _____ _____ _____ _____500 ~ h

19 '375W1490 -450 IL

1445 -525

675

750

120' *1

3p360 33 300 270 2n0

75 536

225 H ----- -,

ISM .--.. -.............

2zS-~~~~~~ ........ ...... . .. .. .. . ............ .. "

22 05- ---------- -------

w 50 ---------------------------------------------

.375 1495 ........z1 450- 1490. .. .

IK)-w4

52 45

6750

Fig. 81 - Contoured Shallow Crow Section of Sound

i

J


20IO5! 20 60ILS

LEGEND'rI SATIONLOCATIONS

&-.-iOn of Sound Velocity, Event 9-5 (Propagation Loue and Arrival Structure), from about 24030'N,165 0 20'W to FLIP *

59(Page 60 Blank)

60NOMINAL FLIP POSlT1 2?35N574ww

5630 75

1520 150

-225

1505

1490 -50 CL.

600

-6Th

240 30'N,1650 20'W to FLIP

__ 5'

- J

60-30 0 30 60 90 120 150 IS0 210 240

266 05' N157*19'W

750-

225-

300-

V 35 IrI450-

20M

675-

-0 0 30 60 90 120 150 ISO 210 240RANGE FROM MAHI (NAUTICAL MILES

Fig. 32 - Shallow Sound Velocity Profiles, Events 11-1 and 11-2 (Propagation Lose and Temporal

61(Page 62 Blank)

41 * -r- w

1. MAHI position: 26-09'N,1570 41'W2. Observations are plotted at actual range from MAHI along top scale3. Lietter at bottom of profile indicates source of data:

C - CONRADM - MARYSVILLER -REXBURG8- SANDS

ISO 210 240 270 300 550 360 390 420 450 460

F33' 19'N

157*14'W

611(Page2 82/Bank

MAH1 POSITIOt4 26009N , l57041 15 w 00IoISO

75 1530 pl1525 _______

150 1520

,WWO 1500-1.-0,

.450-

525-15

600-

675-~

750-

Fig. 33 - Contoured Shallow Cross Section of Sound VelocityJ

RANGE FROM MAHI (NAUTICAL MILES)NORTH--

110 210 240 270 300 330 310

- - - - - - - - - - - - - -- - ------------ - - - - - - -

- - - - - - - - - - - - -- -------------

---------- --------------------------------------------------- iBT-T STATION LOCATIONS

Ion of Sound Velocity, Events 11-- and 11-2 (Propagation Loss and Temporal Fluctuation of CW Signals), MAHI to about 33020'N and Return

74

63

(Page 64 Blank)

300 330 360 390 420 440I I I II - ! I: 7

--- - ------- ----- - s -1500-1- -

----------- ' IS

-- -- --------------225

S' . - -300

It-------------- ýf-------- ---- 37w-------- --------------------------- ------------------- 4N50 a,

--------------

"r . .. . .- •-525

-bOO

ation of CW Signals), MAHI to about 33020'N and Return

j

JI


1 NNW

-300 -200 -oo 0 100 200 300 400 500 6oo 700

27* 59'N 3 ,WN15?' 58'W. •

75-

I

150-

225

I--375

45020 M/SEC

525 -

600-

1. Nominal FLIP position: 27 0 35'N,1570 44'W675 2. Observations are plotted at actual range from FLIP along top scale

3. All profiles from AXBT's dropped on LAC-1 flight of 17 November 1969

750 I I I I I --0 -200 -100 0 100 200 300 400 500 G00 700


Fig. 34 - Shallow Sound Velocity Profiles, Event 13-1 (Long RangePropagation Loss, Aircraft), Adak to FLIP

a

65L(Page 66 Blank)JA

LJ

-3010 -200 -100 0 100 200 300 400 500 600 700 Bo0 900 1000 1100 12000

2704V N157- 02' W

225-

300-

Stl 375 ,12OM/SEC

525

675

2-00 -I10 I0 200 300 400 800 900 I000 1100 12001RANGE FROM FLIP (NAUTICAL MILES)

Fig. 35 - Shallow Sound Velocity Profiles, Event 13-3 (Long Range Propaga

67(Page &G Blank)

o00 900 1000 1100 1200 1300 1400 1500 600 1?00 100 1900 2000 2100 2200 2300

rr

1. Nominal FLIP position: 270 35'N,1570 44'W2. Observations are plotted at actual range from FLIP along top scale3. All profiles from AXET's dropped on LAC-3 flight of 23 November 1969

Soo0 900 w00 1100 1200 1300 1400 15000 0k 10 1000 0 5k~ 210 200 30RANGE FROM FLIP (NAUTICAL MILES)

ty Profiles, Event 13-3 (Long Range Propagation Loss, Aircraft), San Diego to FLIP

67(Page 68 Blank)

:-- "C

g2...................

These classified figures are to be used in conjunctionwith Maury Center Report 006, Volume 2, PARKA II-A, TheOceanographic Measurements. They are being distribu-te-iseparately to permit the basic publication to be used onan unclassified basis.

SOUND VELOCITY (ME

0 SOUIND................. ................................ ................................... .. o...#...•.,

15000 ..... ..... c

I -

I- 2000-

2500-

3000-

3500-

4n iý -1 110 100 900iII

, 600 1500 1400 1300 1200 I100 NO 00 900 1Oo510 34 N, 17613' W 4803 N, 172206W 45-16'N,16940W 4225N,167i6W 3931N, I

ADAK RANGE FROM FLIP

Fig. 36 - Bathymetric Profile and Predicted

Sii

Deputy AssiStant Ocea•aographer forJECT TO ...... AT (Pag

CUTIVE ORD43-ý I6f UJ R INTLRVALS A,, D-CLASSIFIED ONi 31 D - (Page70r

(insert ye

SOUND VELOCITY (METERS/SECOND)

SOUI.'D CH4ANNEL AXIS

-1000

S...... . so #I,too.... C _A #N _L . ... #XS............ " .....................................................

2000 IF

; y - 3500I -3000

YNOTES. 1) DEPTHS CORRECTED FOR VARIATIONS IN SOUND VELOCITY-302) BATHYMETRIC PROFILE BASED ON DATA COLLECI ED BY R/V CONRAD, 19693) SOUND VEI.OCITY PfROFIýES COMPUTEDI BY FNWC FR(qM ARCHIVAL IIANSEN CAST DATA 40

,i%' 9 00 a mo 7oo 6 00 5 00o 40 0 3 0 0 20 0 10 0 0 -,o o j

N,167e16W 3903i'N, 65*O5'W 36*3eN, 163004W 33 38N, 16112'W 30 38'N, 15927W 27 36N, 15749VW

-INGE FROM FLIP (NAUTICAL MILES) FLIP

S•ymetric Proile and Predicted Soend V elocitj Structure, FLIP to Adak

89(Page 70 Blank)

SOUND VELOCITY (METERS/SECO•

00

15000 (CNR0R T

90710 /SOUND..4 WOO ........

II 1 • , orroe.. ... .. ... .. ... .. • . . . . . . . . . . .\:

4000

-400 300 -200 .100 0 100 200 300 400 500 600 70021053'N, 57*50'W 27*35!N, 157*50'W 30055*N, 57*50W 415'N, 157050'W 3?35'N, 157*50'W 40

OAHU FLIP RANGE FROM FLIP (NAUTICAL

Pig. 37 - BDthymetrie P•otile and Predicted Sound V 1

Secret, Secre -

r•C- TOt " -___ , &C+ 3f

of+•+ •. . ,•.. ...'++ • . . .• +l +' ' 71

.J r vtt yert'! (Page 72 llmnk)

. + -1

14dDVELOCITY (METERS/SECO)

........ -e- 0

......... .... ..... ...... .. .....

..17 ......... ----- .... .. ........ ----- ---

.. .......... ...... . .....

7 35N 557 c~ U- :~ -

100 0

I5 I

....... ~~ . .. . . ...... V.W RMA CIA A S ATDT3c~~~~J~ w L35l l.0010

jii

1000

1500

32000

35W0

2?, M'N, 1574dW 23N, 154FLIP

J., &AlMEY'cret, 7-* 1. c leputy Assistant Oceanoraphe 3 .oor

TO .AT

(insort year)

SOUND VELOCITY (METERS/SECOND)

8o r •....... o _......... "1 1 1 T-1

SOUND CHANNkjE4L -------- ---- ------------------. .

F F HE SOU/ND- CHANNEL--

NOTES, 1I) DEPTH"

2) SATmYMi

p p I I3) SOUND

100 200 300 400 5 00 600 7(0 ooSo 3O 1100 1200

Fig.38 Bat ymoricProfile and Predicted Sound Velocity Structure, FLIP to

73

(Page 74 Blank)

-I --

nowO

0O Iwo1500

1500 iO

-----------------.... f........... .......------ 00!

-2500

I) DEPTHS CORRECTED FOR VARIATIONS IN SOUND VELOCITY2) BATHYMETRIC PROFILE BASED ON DATA COLLECTED BY USNS SANDS, 1993) SOUND VELOCITY PROFILES COMPUTED BY FNWC FROM ARCHIVAL NANSEN CAST 'A 3500

I i I i I | I I-I4000

1300 1400 1500 1600 1700 1600 1O0 2000, 2100_.13510W 32*25N, 13I5' W 323iN, 12"184W 32#45'N, 118B59'W

SAN DIEGO

*, FLIP to San Diego

.I

r~o~m14. - ,.

SOUNO VELOCITY (M

,• • ,. ' • 'r• •÷ 0 , •E O I Y ( E T E R S / S E C I

500 ~ ~~~~~~ ----------- ------- ---- --- --------- ---- - ------. . .... . ....... Sol/N C' "SE- i

--0------

--- --- --- --- --

1000

1500

K 2000 orrom OF rH£ --------- ......

3SOU0

------------------------------------ ------------------------------------------------

3000

3500WT

40004100 0 t00 200 300 400 600 700

27 32'N, 157?*4'W 3 0O00N.155011,W 32026'N, 152*31'W 3840'N, 14041W 3 706N, 14 642'W 3919N, 14303&FLIP

3 e SN 4 °1W3 e 6N 4 e2W3 e9N 4 e ••

RANGE FROM FLIP (NAUTICAL .

Fig. 39 - Bathymetric Profile and Predicted Sound Veol

Secret, B'* - DeputY 5istant Oceanographerfor

'0T TO Cw~7IT I V : '. •, 0' E.

.TIVE 0•,.,J+ 'o D 'EA VE O L

(ins..rJ yeJ) (Page 76 Blank)

,: ji•:

" R INT.ERVALS ~t

bOUND VELOCITY (METERS/SECOND)

Aeo) 0

-'NDO CHANNEL AXIS ............................... . ......................... ..----. . ................... -500

1ý y 1000

rHp i i-------- --S................. ....... ....... ..... 15 00 i

CHAF~gk~-RIT/CALSO NDCHAN NEýL ... ..............rHE ---------------..

NOTES: I) DEPTHS CORRECTED FOR VARIATIONS IN SOUND VELOCITY2 ) BATHYMETRIC PROFILE: BASED ON DATA COLLECTED BY USCS GSS MCARTHUR, 1969 -3500

3) SOUND VELOCITY PROFILES COMPUTED BY FNWC FROM ARCHIVAL NANSEN CAST DATA

: III I I I I - I I 1 i 4000

900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

42'W 3919'N, 143132'W 41e26 N, 140 IO'W 4328e N, 136* 35'W 4522' N, 132045'W 48- 30'N, 1250d W

"NGE FROM FLIP (NAUTICAL MILES) SEATTLE

* and Predicted Sound Velocity Structure, FLIP to Seattle

75

(Page 76 Blank)

S2'I


not intrude into the sound charmel in this San Diego. This 1000-meter decrease in theregion. The presence of dichothermal/mesot.her- critical depth is more than matched by a 1500-mal conditions are evident in Fig. 37 and to a meter decrease in the average bottom depthlesser extent in Fig. 36. between FLIP and San Diego. The amount of

In summary, along the two PARKA tracks excess depth is usually oniy about 500 meters,in particular, but also more general'y over a and in some places is zero. At a range of aboutlarge portion of the northern North Pacific, we 500 nautical miles and at several other greatercan expect improvement of coupling of the ranges, convergence zone propagation is seri-source to the sound channel as the source moves ouslv hindered by seamounts penetrating thenorthward. The improvement is a consequence sound channel.mainly of a shoaling axis, and a decrease in the At a range of about 1300 nautical miles,critical depth. This funneling effect should begin the presence of Boundary Water ir the upperto be prominent when the source reaches 42°N several hundred meters of the water column

could affect acoustic propagation through theSan Diego Aircraft Run area. Figure 38 lacks sufficient profile density(Events 13-3 and 13-4) and detail to display adequately the velocity

conditions in this region, but the near-surface

Three water masses affect sound propaga- sound velocity structure is typically more com-tion along the great circle track between FLIP plex here than that found on either side of theand San Diego. These water masses extend to boundary zone. Transitory secondary sounda depth of several hundred meters. North Pacific channels in the near-surface layer are frequentlyCentral Water, described in Section HI, is located found in and near the boundary region. Figurealong the western part of the track, and Tiansi- 40 (from Christensen and Lee, 1965) indicatestion Water is found adjacent to the coast of the different vertical structures that may be -4

Southern California. Boundary Water lies be- found in the area.tween these two water masses and has a hori- Transition water dominates the area nearzontal extent of several hundred miles at the San Diego: Figs. 35 and 38 provide representa- Ilatitude of San Diego. The Boundary Water tive sound velocity profiles for this water mass.zone coincides closely with the CaliforniaCurrent, whose effects also extend to a depth FEATURES OF SOUND VELOCITY PROFILESof several hundred meters. FATURE FISUND SITE

The major features of the vertical sound AT THE FLIP/SANDS SITE

velocity structure in the presence of North Figure 41 shows a sequence of four soundPacific Central Water can be seen in Fig. 38 velocity profiles spanning a period of aboutand are generally similar to those described three weeks. These profiles were taken bybelow for the FLIP area. The axis of the sound SANDS near FLIP, and, for illustrative pur-channel remains deep (between 700 and 800 poses, may be considered a times-series. Themeters) from FLIP all the way east to the Cali- only distinguishable change during the three-fornia coast. The critical depth, however, week period is a slight reduction in the sounddeepens from about 4500 meters (2460 fathoms) -locity maximum in the mixed layer, whichat FLIP to over 4600 meters (2520 fathoms) at reduces the value for critical depth and s'ightlya range of 600 nautical miles, then shoals grad- improves propagation via the convergence zoneually to about 3500 meters (1910 fathoms) off path.

77

__


There is a noticeable positive sound veloc- variability, differences in the way the data wereity gradient in the mixed layer, representing coded, or any combination of these. Figure 44isothermal conditions dominated by the pressure shows a comparison between another pair ofgradient. The positive gradient in the layer would temperature profiles resulting from a CONRADsupport propagation via the surface duct, the STD observation and a coincident XBT. Themean depth of which is approximately 70 meters. agreement shown here is excellent, with theA time series plot of SANDS XBT's, shown in greatest difference (four meters) occurringFig. 42, indicates the variability of the near at the bottom of the mixed layer. In general,

'orface environment during PARKA Il-A. the CONRAD system agreed quite well withMany complexities of the profiles in the data from other systems taken at approximately

depth interval between the mixed layer and the the same location and time.sound channel axis are reflected in corresponding XBT's, however, can be 4 uite erratic; atemperature-salinity (T-S) diagrams. Some illus- thorough analysis of XBT data taken during ]trative T-S plots are presented in Fig. 5a in PARKA I (Whalen and Northrop, 1971) indi-Section III, Part A. The sound channel axis cates that individual XBT probes will sometimesmean depth of about 750 meters, and mean give erroneous results, and that these discre-velocity of about 1480 insec agree closely with pancies can be difficult to detect. Also, as men-archival data. The slight shoaling of the critical tioned in Section I11, Part A above, layer depthsdepth during the period of observation is in this region do change by more than 22 metersundoubtedly the result of seasonal cooling. The over a period of time (Fig. 10); internal wavesaverage depth excess (the distance between could cause such a change. Therefore, the causethe bottom of the sound channel and the bottom of the difference between the two traces givenof the ocean) is about 1000 meters, and thus in Fig. 43 cannot definitely be identified.convergence zone transmission is reliable forthis time of year. Comparison of Computed and

Measured Sound Veloeitles

COMPARISON OF SOUND VELOCITY DATA During the PARKA iI-A Experiment, an

FROM DIFFERENT SYSTEMS attempt was made to compare values of soundvelocity measured with velocimeters aboard

XBT's Compared with STD System SANDS and MARYSVILLE with other dataFigure 43 displays the shallow portion of computed using measured temperature and

two CONRAD temperature profiles, one from salinity data in Wilson's equation (Wilson,

an XBT and the other from an STD station. Two 1960). SANDS employed an NUS Model TR4obvious discrepancies between these profiles velocimeter and an NUS Model 1210-004 depthcan be seen: a change in the depth of the layer, gauge. MARYSVILLE employed an NUSand an offsaft of the profile in the region of the Model 1630-002 sound velocity/temperature/thermocline. pressure sensor. STD measurements from CON-

The large change in layer depth (22 meters) RAD were used as the inputs to Wilson's equa-and the noticeable thermocline offset may both tion to compute sound speed. The Lamont-result from a number of factors: the difference Doherty Geological Observatory providedbetween the times and locations of the two corrected salinity and depth data for use inobservations, instrument error, environmental Wilson's equation. The computations were

78

S. .. ... .. .. .. . . ... .. . . .. . : - - ... .. .. , .. .-. ..... . .. , ... . . .. .,


.9Iin

i I V.

~ Si; 11!!

Moi2l"W) k14130I

79(Poge 80 Blank)

170000NOV 180000 190000 200000 210000 220000 230000 240000 250000 260000 21

ISO-

225 '

300O

375-; ',-,, / /!

1- ///450-:1

525-//

I700 0NOV 180000 190000 200000 210000 220000 230000 240000 250000 260000

Fig. 42 - SANDS i

.-

~.~ -= ~ ".-". -. '. .

1. ProfilUs are plotte42. All profiles fromq

200 260000 270000 280000 290000 300000 010000DEC 020000 030000 040000 050000 060000 070000 060000 090000

ill I

•so oo0 0 0 1o c )o o 030 0 00 05o o•o o o • o o o .o 4 o00 o 50 0 0 60000 0e o 70 0 00 o9o0o o

Filg. 42 -- SANDS Time-Serle Plot of Shallow Sound Velocity Profiles

( 2

/]

'I I(Pge82Blnk (

1. Pfofile, are plotted at time (GMT) obgM~vtioA made2. All profiles from SANDS XBT data

00'OWODEC 020000 030000 040000 0S G 700 OM 000 000 IW M

01 30 00 04 00 O M W0 0 0 00 0 00 00 11 00 M OI

Velocty Prfile


TEMPERATURE(C)015 2D 25

50 CONRAD STD27*49'N 15T*44 W 11600Z 25 NOV69

100

10 /Fig. 43 - Example of Variability of the Near-SurfaceWo/ Temperature Structure

W

W 20 00

250I,"

300CONRAD XAT TEMPERATURE (C)

27*39'N 157144'W C2120Z 25 NOV 69

350 I [CONRAD STD

3501 1200Z SO NOV 69 ]

50-

I00,

1 50 -w

Fig. 44 - Example of Agreement Observed Between -

aTemperature Profiles Obtained by Different Systems -

UJ 200

250

300 -

C CONRAD XOT1200Z 30NOV69

350

83

4


carried out in accordance with U.S, Naval SOUD 4 SPEED IO0SEC)

Oceanographic Office Special Publication 58 0 1 1 1 1 1 1 1(1962).

Because questions arose concerning the -precision and consistency of the sound velocitymeasurements that were made during thePARKA I Experiment (Whalen and others, 10DD1971), considerable care was taken during thePARKA i1-A Fxperiment to ensure that thesound velocimeter systems aboard SANDS IOo0and MARYSVILLE were kept in accuratecalibration. The basic difference between thePARKA I and PARKA i1-A results is that there 20-0

was better compensation in the depth gaugeelectronics for the second experiment. Also, MARSVILLEANDSAND

the SANDS velocimeter was calibrated prior DATA ARE MEASURZD.

to the operation and no significant changes were CONRAD DATA ARETACOMPUTED FROM

found when it was recalibrated upon completion 3o MEASURED TEMPERA-3000 -TURE AND SALINITY

of the exercise. The depth gauge was calibratod OBSERVATIO14S

only prior to the operation, because the initialv "pressure setting had 'ot changed since the 35' MARYSVILLE VELO-

original calibration. The complete sound veloc- 27*32'N 57*43'W

imeter system aboard MARYSVILLE was cali- DEPTH 5450 ME

brated before and after the PARKA II-A , SANDS 15739'

Experiment. 2217Z 24NOV,9DEPTH, 5500 METERS

Figure 45 shows three superimposed veloc- 4500 -ity profiles, two from direct measurements and CONRAD STO27"39'N 157e44'W

one constructed from Wilson's equation. The DEPTH 556 METERS

abscissa scale has been expanded in order to 0oodisplay more clearly the differences in soundvelocity between the profiles. The profiles fromSANDS and MARYSVILLE were recorded o-

by velocimeter about two hours and -.even nauti- Fig. 45 - :omparison Between Twocal miles apart. The CONRAD STD profile Measured and One Computed Soundwas taken in the same area, but about 20 hours Ve~ocity Profilelater. Table 2 lists velocity values from the Figure 45 and Table 2 show very closethree systems. agreement between the two sound velocimeter

In Fig. 46 a MARYSVILLE measured systems used during the experiment. The ob-profile and a CONRAD computed profile (via served differenct , appear mainly in the thermo-Wilson's equation) are shown. These two sets cline region, and probably can be accounted forof values, also quasisynoptic and taken within by the changes taking place in the medium overa few miles of each other, are listed in Table 3. a period of several hours. However, inspection

84

41

........................................................


S.. . ' I I I I' ' . .. . .. I

_! <ý

5 S

CA

<~ f4" ..• L a'. . . . . . . . .

Z -J

Z S I SIý

> en m 00 00

U - -

85

--.-

SOUND VELOCITY 9TRUCTURE

SOUN SPEED01 00 SEC) of the sound velocimeter systems used did not1470 14Wo 1490 150 151 15o 1530 154015 150so,0 produce accurate depth measurements (Whalen

and others, 1971). These differences, however,tended to increase proportionately with depth.

o: - In addition, although PARKA I computed soundvelocities were also somewhat higher than the

IWO - _measured values, no real comparison was at-tempted, for several reasons. In PARKA i, mostof the sound velocity computations were made

I0O - with archival salinities, due to a lack of any deepPARKA salinity data (Wolff and Lackie, 1971).This use of archival (or assumed) salinity data

2000 - occasionally caused differences of 0.1 to 0.2

m/sec ir sound velocity, when compared with,200sound velocities computed from measured

MARYSVILLE DATA ARE salinities. A "rounding off" error in the FNWCAMEASRE .COWFROATM computation program also caused minor dis-

30 MEASURDTE-'ATU• crepancies between profiles. Any attempt ata14 3000 -AND SALINITY OBSER--VATIONS comparing computed and measured values was

also overshadowed by the uncertainity caused3500 - by the inaccurate depth measurements refer-

enced above (Whalen and others, 1971). Due to

these uncertainties, the small differences notedoARYSVILLE VELOCIMETER between measured and computed sound veloc-27029'N 057N38VW ities in PARKA I were not considered to be00O332 30 NOV 69

DEPTH, 5520 METERS significant.CONRAD STO The discrepancies discovered in PARKA27*30'N 157"43*W

1200Z 30NOV69 11-A are consistent, and suggest constant offset.50DT - Although some of the problems (such as the

rounding off error) may continue to influence thePARKA I-A data, a different explanation may

5500 1 be required. Recently, Carnvale and othersFig. 46 - Comparison Between a Mea- (1968) made a detailed laboratory comparisonsured and a Computed Sound Velocity of sound speeds using various methods of

Profile measurement. Although pressure and salinity

of both figures reveals a consistent discrepancy effects were not considered, it was found thatbetween directly measured and computed values in the 00C to 25°C temperature range, valuesfor depths below the sound channel axis. Values obtained from Wilson's equation were consis-determined from Wilson's equation in this re- tently higher than those measured directly bygion are all 0.5 m/sec or more higher than those 0.2 to 0.3 m/sec. This may, at least partially,measured directly. It also appears that this account for the observed disci'epancy. Althoughsystematic difference is independent of depth. this observed bias is not apparent above theDuring PARKA 1, the pressure sensors in some sound channel axis, it may be overshadowed by

86

I


TABLE 3Comparison Between CON RAD (Computed) andMARYSVILLE (Measured) Sound Velocity Data

CONRAD MARYSVILLE Differences in1200Z, 30 Nov 69 0033Z, 30 Nov 69 Sound Velocity

Depth 27030'N, 157043'W 27029'N, 157 038'W (m/sec)(M)

Sound Velocity Sound Velocity CONRAD-(mlsec) (mlsec) MARYSVILLE•

0 1531i.5 1530.0 1.5

50 1532.3 1531.9 0.4100 1523.5 1527.1 -3.6200 ;514.7 1514,0 0.7300 1502.9 1504.4 -1.5400 1493.7 1493.0 0.7500 1487.5 1487.7 -0.2600 1482.9 1483.7 -0.8700 1482.3 1481.3 1.0800 1481.6 1480.9 0.7900 1482.0 1481.2 0.8

1000 148216 1482.0 0.61200 1483.8 1483.2 0.61500 1486.5 1486.0 0.52000 1492.2 1491.0 1.2 j3000 1506.8 1506.0 0.8

4000 1524.1 - -5000 1541.0

medium variability there. It should be stressed, II-A is considered generally excellent. Discrep-however, that our comparisons have a small ancies noted between measured sound velocitiesdata base. Future comparisons of this type and those computed from measured temperatureshould be based on several simultaneous stations and salinity data may be due to minor inaccura-at the same location, using as many different cies in Wilson's equation used in the computa-measuring systems as possible, tions. These discrepancies, however, will

Agreement between the various environ- probably have a negligible effect on the useful-mental sensor systems employed in PARKA ness of the data in predicting sound propagation.

87

J

REFERENCES

REFERENCES

Carnvele, A., Bowen, P., Basileo, M., and 1l-A operations": Hawaii Inst. of Geophys.,Sprenke, J., 1968, "Absolute sound velocity Interim Tech. Rept. n. 4.measurement in distilled water": Jour. Latham, R. C., Budd, R., and Zacharladis, R.Acoust. Soc. Am., v. 44, n. 4, p. 1098-1102. G., 1969, "Report of work accomplished in I

Christenaen, N. and Lee, 0. S., 1965, "Sound support of PARKA 11 operations": Hawaiichannels in the boundary region between Inst. of Geophys., Interim Tech. Rept. n. 3.Eastern North Pacific Central Water and Maury Center for Ocean Science, 1969a,Transition Water": Second U.S. Navy "PARKA 11, GNR scientific plan 2-69":Symposium on Military Oceanography, Pro- Washington, Maury Center for Oceanceedings, v. 2, p. 203-225. (CONFIDEN- Science Plan 01. (CONFIDENTIAL re-TIAL report, Unclassified title) port, Unclassified title)

Hansen, P. G., 1969, "A sea going UNIVAC Maury Center for Ocean Science, 1969b, "The1218 interfaced with NUWC's thermistor PARKA I Experiment": Washington,chain": Applications of Sea Going Coin- Maury Center for Ocean Science Rept.puters, 1969, Symposium Transactions, 003, v. 1, 82 p. (SECRET report, Unclas-Washington, Marine Technology Society, sifted title)p. 105-114. MeGary, J. W., and Stroup, E. D., 1956, "Mid-

Hesselberg, T. and Sverdrup, H. U., 1915, Pacific oceanography, Part VIii, middle

"Stability conditions of sea water at verti- latitude waters, Jan-Mar 1954": U.S. Fik'hcal displacement": Bergen Museum Year- and Wildlife Serv., Spec. Scient. Rept. -book 1914-15, n. 15, p. 1-16. (Translation Fisheries, n. 180.by U.S. Navy Hyd.. graphic Office, 1962) NORPAC Committee, 1960, "Oceanic observa-

Jacobs, W. C., 1951, "The energy exchange tions of the Pacific: 1955, The NORPACbetween sea and atmosphere and some of its Atlas": Berkeley and Tokyo, Univ. ofconsequences": Scripps Inst. Oceanog. California Press and Univ. of Tokyo Press.Bull_, v. 6, n. 2, p. 22-122. Patzert, W. C., 1969, "Eddies in Hawaiian

Lackle, K. W., 1971, "Review" (of PARKA I waters": Hawaii Inst. of Geophys., Rept.environmental operations), Appendix B I 69-8.to the PARKA I Experiment: Maury Cen- Pickard, G. L., 1963, "Descriptive physicalter for Ocean Science Rept. 003, v. 2, 165 p. oceanography": Oxford, Pergamon Press,(CONFIDENTIAL report, Unclassified 200 p.title) Reid, J. L., 1965, "Intermediate waters of the

LaFon,,, E. C., and LaFond, K. G., 1971, "Ther- Pacific Ocean": Baltimore, Johns Hopkinsmal structure through the California front": Univ. Press, 85 p.Naval Undersea Research and Develop- Roden, G. I., 1964, "Shallow temperaturement Center, Tech. Pub. 226, in press. inversions in the Pacific Ocean": Jour.

Latham, R. C., 1970, "Environmental oceano- Geophys. Research, v. 69, n. 14, p. 2899-graphic observations in support of PARKA 2914.

88

SC0NFIDENTjL ,REFERENCES

Roden, G. 1., 1970, "Aspects of the Midacific Sverdrup, H. U., Johnson, M. W., and Fleming,Transition Zone": Jour. Geophys. Re- R. H., 1942, "The oceans": New York,search, v. 75, n. 6, p. 1097-1109. Prentice Hall, p. 605-761.

Rudnick, P., and Hasse, R. W., 1971, "Extreme Uda, M., 1963, "Oceanography of the Sub-Pacific waves, December 1969": Jour. arctic": Jour. Fisheries Research BoardGeophys. Research, v. 76, n. 3, p. 742-744. Canada, v. 20, n. 1, p. 119-179

Seckel, G. R., 1962, "Atlas of the oceanographic U.S. Naval Oceanographic Office, 1962, "Tablesclimate of the Hawaiian Islands region": of sound speed in sea water": Washington,U.S. Fish and Wildlife Serv., Fishery Bull., Spec. Pub. 58, 47 p.n. 193. Whalen, T. L., and Northrop, J., 1971, "WHO[

Seckel, G. R., 1969, "Vertical sections of tern- oceanographic operations" (in PARKA 1),perature and salinity in the trade wind zone Appendix Bit to The PARKA ! Experi-

of the central North Pacific, February 1964 ment: Maury Center for Ocean Science,to June 1965": U.S. Fish and Wildlife Serv., Rept. 003, v. 2, 165 p. (CONFIDENTIALCirc. n. 323, 43 p. report, Unclassified title)

Smith, E. L., 1967, "Migration and temperature Whalen, T. L. Northrop, J. and Lackie, K. W.,structure of eddies on the ieeward side of 1971, "Data quality" (of PARKA I ocean-the Hawaiian Islands": Fourth U.S. Navy ographic data), Appendix B3 to TheSymposium on Military Oceanography, Pro- PARKA Experiment: Maury Center forceedings, v. 1, p. 396-414. Ocean Science, Rcpt. 003, v. 2, 165 p.

Smith, E. L., 1969, "Sensor depths and digital (CONFIDENTIAL report, Unclassifieddata correction methods for a towed therm- title)istor chain": Naval Undersea Research Wilson, W. D., 1960, "Speed of sound in seaand Development Center, Tech. Note 313, water as a function of temperature, pressure17 p. and salinity": Jour. Acoust. Soc. Am., v. 32,

Smith, E. L., 1971a, "NURDC oceanographic p. 641. Revised and extended in v. 32, p.operations" (in PARKA i), Appendix B7 1357, 1960, and v. 34, p. 866, 1962.to the PARKA Experiment: Maury Center Wolff, P. M., and Lackle, K. W., 197 1, "Salinity"for Ocean Science, Rept. 003, v. 2, 165 p. (in PARKA 1), Appendix B9 to The(CONFIDENTIAL report, Unclassified PARKA I Experiment: Maury Center fortitle) Ocean Science, Rept. 003, v. 2, 165 p.

Smith, E. L., 197 lb, "Aircraft expendable bathy- (CONFIDENTIAL report, Unclassifiedthermograph observations" (in PARKA 1), title)Appendix B8 to The PARKA I Experiment: Wyrtki, K.. 1967, "The spectrum of ocean tur-Maury Center for Ocean Science Rept. bulence over distances between 40 and 1000003, v. 2, 165 p. (CONFIDENTIAL re- kilometers": Deutsche Hydrograph.port, Unclassified title) Zeitschr., Jahrg. 20, Heft. 4, p. 176-183.

89

A, 1" -u''."•o -~:.-!Jiiieak•,

DEPARTMENT OF THE NAVYOFFICE OF NAVAL RESEARCH800 NORTH QUINCY STREET

ARLINGTON. VA 22217-5660 IN REPLY REFER TO

5510/1Ser 93/16010 Mar 99

From: Chief of Naval ResearchTo: Commander, Naval Meteorology and Oceanography Command

1020 Balch BoulevardStennis Space Center MS 39529-5005

Subj: DECLASSIFICATION OF PARKA I AND PARKA II REPORTS

Ref: (a) CNMOC ltr 3140 Ser 5/110 of 12 Aug 97

Encl: (1) Listing of Known Classified PARKA Reports

1. In response to reference (a), the Chief of Naval Operations (N874) has reviewed a number ofPacific Acoustic Research Kaneohe-Alaska (PARKA) Experiment documents and hasdetermined that all PARKA I and PARKA II reports may be declassified and marked asfollows:

Classification changed to UNCLASSIFIED by authority of Chief of Naval Researchletter Ser 93/160, 10 Mar 99.

DISTRIBUTION STATEMENT A: Approved for public release. Distribution isunlimited.

2. Enclosure (1) is a listing of known classified PARKA reports. The marking on thosedocuments should be changed as noted in paragraph 1 above. When other PARKA I andPARKA II reports are identified, their markings should be changed and a copy of the titlepage and a notation of how many pages the document contained should be provided to Chiefof Naval Research (ONR 93), 800 N. Quincy Street, Arlington, VA 22217-5660. This willenable me to maintain a master list of downgraded PARKA reports.

3. Questions may be directed to the undersigned on (703) 696-4619, DSN 426-4619.

PEGGY LAMBERTBy direction

Copy to:NUWC Newport Technical Library (Code 5441)NRL Washington (Mary Templeman, Code 5227)NRL SSC (Roger Swanton, Code 7031)

•/DTIC (Bill Bush, DTIC-OCQ)

Continuation of LRAPP Final Report, February 1972, Contract N00014-71-C-0088, Bell TelephoneLabs, Unknown # of pages(NUSC NL Accession # 057708)

PARKA II-A, The Oceanographic Measurements, February 1972, MC Report 006, Volume 2, MauryCenter for Ocean Science (ONR), 89 pages(NUSC NL Accession # 059194) (NRL SSC Accession # 85007063) 9 J-, 3Y•,

Project Pacific Sea Spider - Technology Used in Developing A Deep-Ocean Ultrastable Platform,12 April 1974, ONR-ACR-196, 55 pages

/(DTIC # 529 9451

LRAPP Program Review at the New London Laboratory, Naval Underwater Systems Center, 24 April1975, NUSC-TD-4943, Unknown # of pages(NUSC NL Accession # 004943)

An Analysis of PARKA IIA Data Using the AESD Parabolic Equation Model, December 1975, AESDTechnical Note TN-75-09, Acoustic Environmental Support Detachment (ONR), 53 pages(NRL SSC Accession # 85004613)

Bottom Loss Measurements in the Eastern Pacific Ocean, 26 January 1977, NADC-76320-20, 66 pagesA(DTIC # C009 224)

PARKA I Oceanographic Data Compendium, November 1978, NORDA-TN-25, 579 pages/(DTIC # Bi 15 967)

Sonar Surveillance Through A North Pacific Ocean Front, June 1981, NOSC-TR-682, 18 pagesJ/'(DTIC # C026 529)

The Acoustic Model Evaluation Committee (AMEC) Reports, Volume 1, Model EvaluationMethodology and Implementation, September 1982, NORDA-33-VOL-1, 46 pages

V,4DTIC # C034 016)

The Acoustic Model Evaluation Committee (AMEC) Reports, Volume 1A, Summary of RangeIndependent Environment Acoustic Propagation Data Sets, September 1982, NORDA-34-VOL-1A,482 pages

/DTIC # C034 017)'

The Acoustic Model Evaluation Committee (AMEC) Reports, Volume 2, The Evaluation of the FactPL9D Transmission Loss Model, Book 1, September 1982, NORDA-35-VOL-2-BK-1, 179 pages

\/DTIC # C034 018),

The Acoustic Model Evaluation Committee (AMEC) Reports, Volume 2, The Evaluation of the FactPL9D Transmission Loss Model, Book 2, Appendices A-D, September 1982, NORDA-35-VOL-2-BK-

',318 pagesTIC# C034 019)

3

DEPARTMENT OF THE NAVYOFFICE OF NAVAL RESEARCH

875 NORTH RANDOLPH STREETSUITE 1425

ARLINGTON VA 22203-1995IN REPLY REFER TO:

5510/1Ser 3210A/0 11/0631 Jan 06

MEMORANDUM FOR DISTRIBUTION LIST

Subj: DECLASSIFICATION OF LONG RANGE ACOUSTIC PROPAGATION PROJECT(LRAPP) DOCUMENTS

Ref: (a) SECNAVINST 5510.36

Encl: (1) List of DECLASSIFIED LRAPP Documents

1. In accordance with reference (a), a declassification review has been conducted on anumber of classified LRAPP documents.

2. The LRAPP documents listed in enclosure (1) have been downgraded toUNCLASSIFIED and have been approved for public release. These documents shouldbe remarked as follows:

Classification changed to UNCLASSIFIED by.-authority of the Chief of NavalOperations (N772) letter N772A/6U875630, 20 January 2006.

DISTRIBUTION STATEMENT A: Approved for Public Release; Distribution isunlimited.

3. Questions may be directed to the undersigned on (703) 696-4619, DSN 426-4619.

BRIAN LINKBy direction

Subj: DECLASSIFICATION OF LONG RANGE ACOUSTIC PROPAGATION PROJECT(LRAPP) DOCUMENTS

DISTRIBUTION LIST:NAVOCEANO (Code N 121LC - Jaime Ratliff)NRL Washington (Code 5596.3 - Mary Templeman)PEO LMW Det San Diego (PMS 181)DTIC-OCQ (Larry Downing)ARL, U of TexasBlue Sea Corporation (Dr.Roy Gaul)ONR 32B (CAPT Paul Stewart)ONR 321 OA (Dr. Ellen Livingston)APL, U of WashingtonAPL, Johns Hopkins UniversityARL, Penn State UniversityMPL of Scripps Institution of OceanographyWHOINAVSEANAVAIRNUWCSAIC

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