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NOO TR-232

INTERMEDIATE AND DEEP CURRENT
MEASUREMENTS IN THE NORTHEAST
PACIFIC OCEAN

Marshall D. Earle
Naval Oceanographic Office

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enographic Institution }

July 1975

Technical Report
Oceanographic Institution |

Prepared for

Long Range Acoustic Propagation Project
of the Office of Naval Research
and the Chesapeake Division of the
Naval Facilities Engineering Command

Department of the Navy
Naval Oceanographic Office
Washington, D.C. 20373

Approved for public release; distribution unlimited.

FOREWORD

The increasing sophistication of iiaval weapons systems, both fixed
and mobile, requires that oceanographers understand the motions, and the
associated driving and physical forces, of oceanic currents. The studies
which are prerequisite to such knowledge require a tremendous investment
in capital and human resources, but only through such investments will
the Navy approach solutions to its environmental problems. This report
describes the characteristics of intermediate and deep currents in the
central northeast Pacific Ocean, a region where very few direct current
observations have been made.

A aes ARES
Captain, USN
Commander

NN YAU TEL

0 0301 0069178 4

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T. REPORT NUMBER 2. GOVT ACCESSION NO.
TR-232

4. TITLE (and Subtitle)
Intermediate and Deep current
Measurements in the Northeast
Pacific Ocean

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Marshall D. Earle

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Naval Oceanographic Office
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- KEY WORDS

Pacific Ocean, ocean currents, internal tides

20. ABSTRACT (Continue on reverse aide if necessary and identify by block number)

. Ocean currents were measured in the central northeast Pacific, from
30°N to 40°N and 140°W to 150°W, with nine arrays of moored current meters
during autumn 1973. Current meter records at depths from 700 m to 5420 m
were analyzed to determine the characteristics of intermediate and deep
currents within the central northeast Pacific. The currents in this region
have very low speeds which generally decrease with increasing depth. Con-
tributions to the time-dependent currents are primarily from oscillatory

DD , Feaiog 1473 ~— EDITION OF 1 NOV 65 IS OBSOLETE UNCLASSIFIED
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fa AOD és 1 SECURITY CLASSIFICATION OF THIS PAGE (When Data Entered)

LECURITY CLASSIFICATION OF THIS PAGE(When Data Entered)

motions at the local inertial frequencies and the semidiurnal tidal
frequency. Spectral analysis indicates that tidal frequency motion is

essentially due to baroclinic internal tides and not barotropic surface
tides.

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ACKNOWLEDGMENTS

The author thanks the following Naval Oceanographic Office
personnel for their assistance: Donald Burns who provided extensive
help and many suggestions throughout this study; Louis Banchero,
Michael Holland, and Warren Sanborn who placed and successfully
recovered the current meter arrays under very difficult working
conditions; and Robert Guthrie who provided the time series vector
plots and the current speed probability distributions.

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CONTENTS

Page

AGKNOWIMEDGMENT Siwesy cyttc seis eh fem mals. Pet olsen hileoz ys \fe ae deivlsth cdisunce R4ccl ‘6 WW

LNT ROOW CON Mir cit Mon Car. cleric mio go hiemtelomeaticeriaste.¥ 1

DESCRIPMMON NO RSCURRENT MEDERGARRAVS#) ())).ure pee) sh euleiucs ll cell. 1

DESCRIPIMONNO RN MEASUREDNGURRENTS i cir mle dso a) eat elie 2

TIME SERIES ANALYSIS OF MEASURED CURRENTS. .......... 2

PPENNCORVE ae rcleet ine Such ucager tis) on aberny oop cue ehh oaks alia tarrte? 2

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REBERENCES? fa bor apiche bien: vote) isuire# aod Yano Weyiaioh tho: leh st ¢ ciowuhory-loie! csieopepa's gS

FIGURES

1. Locations of Current Measurements. .-.......... 11

2. Example of Time-Dependent Half-Hourly Current Vectors. . . 12
SeO a esEnengyeopectrawAnrnays Boll alemousia i ondus @ isu « 13-20

liluaDepthi Vaniationsonsenengyabensiities... <<. . 2. 6 4. 6 21

12. Rotary Coefficients of Current Records at and above 1,000 m 22

13. Rotary Coefficients of Current Records below 1,000m... 23

TABLES
ee AGrAVMDES Ciel PCUONS ro ct ect uauien saucia slyvesp ous Bere ales vere! ain 25
2. Probability Distributions of Current Speed ........ 27
SpenMecanwcunrentaspeed ands DimeGulOny lle sale. ea) 29
Ae Spectral AnaliysiS#Parameters. scenes coe, s 6) 6 6 6 31

py BRUT SRY

8 00 a

INTRODUCTION

Studies of currents in the northeast Pacific, distant from the North
American continent, have been mainly based on interpretation or analysis
of observed physical and chemical seawater properties. While these clas-
sical techniques provide estimates of the mean and very-low-frequency
circulation, direct current measurements are required to determine higher
frequency time-dependent motion. Very few direct measurements have been
reported in the literature. Reid (1962) and Hendershott (1973) found
significant diurnal clockwise rotation in several series of GEK (geomagnetic
electrokinetograpn) measurements of surface currents near 30°N,125°W.
Bathythermograph observations in the surface layer did not snow significant
diurnal vertical isotherm displacements but did show some indications of
semidiurnal internal waves. Using neutrally buoyant Swallow floats near
28°N,139°W and 29°N,113°W, Knauss (1962) observed diurnal clockwise
rotating currents at depths between 700 m and 3,900 m. Diurnal currents
at different depths were not in phase.. Bathythermograph (BT) observations
by Knauss did not indicate significant vertical displacement of isotherms.
Diurnal motions reported by Knauss (1962), Reid (1962), and Hendershott
(1973) represent inertial period motion. Current measurements from two
moored arrays near 28°N,158°W have been reported (Patzert, Wyrtki, and
Santamore, 1970), but the time series of these measurements are too short
for statistical analysis.

The objective of this experiment was the direct measurement of inter-
mediate and deep currents over a large area over periods of at least one
month. The experiment was not designed as a small-scale study of internal
wave characteristics. Guthrie, Burns and Smith (1974) have described some
of the data on which this report is based. The results reported herein
may later be used as inputs to the design of current measurement programs
concentrating on smaller vertical and horizontal scales. These results
also will be useful in formulating numerical models to compute intermediate
and deep currents in the North Pacific.

DESCRIPTION OF CURRENT METER ARRAYS

Currents were measured in deep water far from the Continental Shelf
near the center of the eastern gyre of the North Pacific Ocean (fig. 1).
Table 1 provides a description of each of the nine arrays. Most arrays
were located over nearly level topography, and no arrays were placed
close to seamounts. In order to reduce motion effects due to surface
gravity waves, each array was supported by a subsurface buoy at a depth
of approximately 500 m. A short section of chain attached to the buoy and
500 m of wire rope supported the first current meter. The remainder of
each array consisted of nylon line with current meters suspended at selected
depths. Geodyne model 101 current meters were used on arrays A through
C, and Geodyne model 102 meters were used on arrays D through I. The
recording interval for all meters was 10 minutes. Each array terminated
with an acoustic release, steel dampening disk, and concrete anchor clump.

Current meter depths in table 1 are based on the assumption that the
nylon line stretched 15 percent of cut length for new line and 12 percent

1

for used line. To estimate effects of mooring motion, a finite element
model (Chhabra, 1973; Chhabra, Dahlen and Froidevaux, 1974) was used to
simulate array motion. The highest measured current speed profiles were
inputs to the finite element model. Time-dependent displacements of the
current meters were found to have a negligible effect on velocity measure-
ments.

DESCRIPTION OF MEASURED CURRENTS

Prior to detailed analysis, all 10-minute current speed and direction
values were resolved into east-west and north-south components. To obtain
an initial description of the current velocity field, individual components
were averaged vectorially to provide half-hour mean current vectors which
were plotted as a function of time. Figure 2 is an example of such a plot.
The plots indicate that the current speeds are very low and that the most
Significant contributions to the time-dependent flow are clockwise motions
at the semidiurnal and local inertial frequencies. Although some current
vector records depict a slight velocity amplitude increase just above the
bottom, currents are generally characterized by a rapid decrease in velocity
amplitudes witn increasing depth. In addition, currents at different depths
are not in phase.

The probability distributions of current speeds are given in table 2 and
mean current speeds are given in table 3. For many of the deep current
records (below 1,000 m), current speeds are often below the threshold
speed (2.5 cm/sec) of the current meters. Although the meters appear to
operate satisfactorily below threshold speed, uncertainty about the meter
calibration and operation below threshold speed indicates that the inter-
pretation of the measured deeper current results should be primarily
qualitative.

TIME SERIES ANALYSIS OF MEASURED CURRENTS

1. Theory

Rotary energy spectra and cross-spectra were computed using techniques
described by Gonella (1972) and Mooers (1973). These techniques resolve
vector current records into clockwise and anticlockwise rotating components.
The east-west velocity component U, (t) and the north-south velocity com-
ponent Up (t), where t is time, can be represented by their Fourier
coefficients (a, b,) and (ay, bo), respectively, as follows:

Go

j [a (c) cos(ot) + b (o) sin(at)] do
(1)

\ [a (c) cos(ct) + b (co) sin(ot)] do
2 2

°

eye
1 ot

Ute = ae
2 on

The radian prequency is given by co. The relationships between the east-
west and north-south velocity components and the rotating Fourier component
representation are given by:

@o
u(t) = 1 (Ale) cos(ot + #(0)) + C(c) cos(ot + 0(0))] de

. (2)
U (t) = ot [A(c) sin(ot + (c)) - C(o) sin(ot + @(c))} do

°

where A and » are the amplitude and phase of the anticlockwise rotating
component, and C and @ are the amplitude and phase of the clockwise
rotating component. In terms of the Fourier coefficients of the east-
west and north-south velocity components, the amplitudes and phases are
given by:

‘ ; 1/2
A= 1/2 & + b.) + (a, - b) (3)
1/2
C= We | yay (Bis | (4)
55 a
fant aceioe (3)
1 2
Py HB,
tan 6 = Blas (6)
2 1

Of particular interest for this analysis are the following rotary
spectra parameters:

Clockwise energy spectrum:
2
Ec = 1/2 © (7)

Anticlockwise energy spectrum:

Ex = 1/2 Az (8)

Total energy spectrum:

Spo Eye Eee We (Ge GP) (9)
Rotary coefficient:
Eamon 10
‘C4 te Sey (10)

In the above and following equations, the overbar represents an average
of a number of frequency contributions, that is, a band average over
values determined at discrete frequencies by a finite Fourier transform.

Rotary cross-spectra were computed between selected current velocity
records. For the measured currents, the dominant direction of rotation is
clockwise. The coherence yc between clockwise rotating components is
given by:

1/2

2 2
fC cos(majomia) Gyce sinoncyenn (11)
NiCr s Man. 1 2 le: 1 2

(Be (es
Wee

where the subscripts 1 and 2 indicate values from different current meters.
The phase difference Xc between clockwise rotating components is given by:

j oi o ri ai % 9 (12)

Cross-spectra between anticlockwise rotating components for different
current records and between anticlockwise and clockwise components for
different current records were determined using methods described by
Mooers (1973).

Standard cross-spectra were also computed between selected east-west
and north-south velocity components. Of primary interest is the coherence
between these components. The coherence y is given by:

: (13)

2. Results

Individual Fourier coefficients were determined using the complex
fast Fourier transform on continuous current records equal to or longer
than 28.4 days (4,096 data points). Each record was divided into
sections containing 2,048 data points for both velocity components, and
each section was separately transformed. No special treatment was applied
to periods of very low or zero current speeds. Frequency bands were
selected to place diurnal, inertial, and semidiurnal frequencies near the
centers of separate frequency bands for most of the current records. To
compress the analysis results at frequencies greater than 0.15 cph, a band-
averaging technique was chosen to make the spectral estimates almost
equally spaced when plotted versus the logarithm of the frequency. To
obtain the analysis results for each current record, band averages were
computed over the corresponding bands within each section of the record.

Total energy spectra are shown in figures 3 through 10. Energy spectra
of currents are not shown for array A, because the record lengths are less
than 28.4 days. Table 4 provides the record lengths and degrees of freedom
which accompany the spectra. The 90-percent confidence bands shown on
figures 3 through 10 apply to frequencies less than 0.15 cph, the region of
the primary contributions to the measured currents. Each spectrum is char-
acterized by peaks at the local inertial frequency and at the semidiurnal
frequency which are indicated on the frequency scale by i and s, respectivel
For arrays B, D, E, F, and G, the local inertial periods are shorter than
the diurnal period, and diurnal internal wave motion cannot occur. At these
arrays, the energy spectra show essentially no diurnal energy (marked by d)
above a noisy background. This finding is particularly evident for the
uppermost records from each location. For arrays C, H, and I, the local
inertial periods are also shorter than the diurnal period but are too near
the diurnal period to allow an accurate separation using the techniques
which have been described.

The depth variations of energy densities for three frequency bands are
shown in figure 11. The diurnal energy is within the band centered at
0.038 cph, and the semidiurnal energy is within the band centered at 0.082
cph. For arrays B, D, E, and F the inertial energy is within the band
centered at 0.053 cph. For arrays C, H, and I, the inertial energy is
within the band centered at 0.038 cph. The energy densities computed for
array G are not included in figure 11, because spectral analysis results
at only three depths may not adequately specify the energy density profile.
Also presented in figure 11 is the depth variation of the Brunt-Vaisala
frequency in the vicinity of the arrays. The plotted Brunt-Vaisala frequency

values were computed from STD (salinify,,, temperature, depth) measurements
made during August 1973. The Brunt-Vaisala frequency decreases nearly
exponentially with increasing depth. The kinetic energy spectrum for ,
baroclinic internal waves is theoretically proportional to the Brunt-Vaisala
frequency. The observed depth decrease of the Brunt-Vaisala frequency
closely resembles the observed depth decrease of the semidiurnal energy
densities. Similar comparisons have been made in the eastern North Atlantic
near the Continental Shelf (e.g., Regal and Wunsch, 1973). At several
locations, the semidiurnal tidal energy density increases as the bottom is
approached. This may indicate that the internal tide interacts with local
bottom bathymetry or that internal waves are being generated near the bottom
by bottom roughness or the bottom boundary layer. Examination of the
topography near the array locations showed no clear correlations between
semidiurnal energy density variations near the bottom and topographic features
or changes in bottom roughness. At locations where the diurnal energy is
separated from the local inertial energy, the diurnal energy density is more
nearly uniform with depth.

Further insight into the current structure is gained from rotary co-
efficients. Figure 12 provides the coefficients for current records at
depths less than or equal to 1,000 m. Figure 13 provides the coefficients
for current records at greater depths. The rotary coefficient is a measure
of the strength of rotary motion. For currents which rotate in a perfect
circle, the magnitude of the rotary coefficient is unity. The sign of the
rotary coefficient is positive for clockwise rotating currents and negative
for anticlockwise rotating currents. Because the current measurements were
made far from continental boundaries and in the Northern Hemisphere, currents
due to inertial and internal wave motion should rotate clockwise. Figures
12 and 13 show that clockwise motion is nearly always observed for
frequencies at and above the local inertial frequency. At these frequencies
internal waves may occur. For the records at 1,090 m which contain con-
siderable inertial and semidiurnal energy, currents at these frequencies
rotate clockwise in nearly perfect circular orbits.

For internal waves, Fofonoff (1969) has shown that the rotary coefficient
is given by:

is 2of
Rc oae Fay ia)

where f is the local Coriolis parameter. Values of Re from equation 14
are indicated on figures 12 and 13 for latitudes bracketing all of the
measurements. Below the inertial frequency, values from equation 14 are
shown by a broken line to indicate that internal waves cannot occur.
Observed values of the rotary coefficient compare well with equation 14
for the upper current records (fig. 12). Agreement is especially good
at the local inertial and semidiurnal frequencies where energy is concen-
trated. Poorer agreement (fig. 13) is expected for the deeper currents,

6

because the low-speed currents result in a low signal-to-noise ratio and
because of bottom influences.

Garrett and Munk (1972) developed an internal wave model which assumes
that the internal wave field is horizontally isotropic. For isotropy, the
coherence between horizontal velocity components has the same form as
equation 14. That is,

= 2of
v ae (15)

where y is the coherence between the east-west and north-south velocity
components. For the current records above 1,000 m, the coherences between
these components are nearly identical to the rotary coefficients in figure
We

Rotary cross-spectra were computed for simultaneous current records at
the same depths less than or equal to 1,000 m at adjacent arrays and for
Simultaneous records at different depths on the same array. At the 1,000 m
depth for arrays E and F which were 1,500 m apart, all frequency bands
with significant energy (0.053 to 0.082 cph) have coherence values between
clockwise rotating components greater than 0.95 and phase differences less
than 31 degrees. These values for these close arrays place confidence in
the measurement techniques. Except for cross-spectra between arrays E and
F, no other coherence values exceed the 90-percent confidence level. Low
horizontal coherences are expected because the experiment was designed with
large horizontal spacings between arrays and because the most important
current contributions are from inertial currents and internal waves which
have horizontal scales smaller than the array spacings except for arrays E
and F.

CONCLUSIONS

This description and analysis of measured intermediate and deep currents
in the northeast Pacific provides the following general characteristics of
the current velocity field:

1. The measured currents, particularly the mean- and low-frequency
currents, nave very low speeds. Low speeds are expected, because the
measurements were made near the center of the eastern gyre of the North
Pacific.

2. Inertial currents, which are concentrated near the surface and are
incoherent over vertical distances, are a major contributor to the current
structure.

3. Semidiurnal tidal frequency currents are significant. Time series
analysis indicates that the oscillatory motion of semidiurnal tidal
frequency is due to baroclinic internal tides rather than to barotropic
surface tides. Semidiurnal tidal frequency currents are also concentrated
near the surface, where the Brunt-Vaisala frequency is largest.

7

4. Time-dependent currents rotate clockwise.

5. Above the local inertial frequencies, the time-dependent currents
are composed mainly of isotropic internal waves.

These characteristics point the way for future studies of intermediate
and deep currents within the northeast Pacific. First, closely spaced
arrays designed to sample small vertical and horizontal scales will be
required for more detailed study of tidal frequency internal waves. Second,
low current speeds may require supplementary use of bagrangtan measurement
techniques such as Swallow or sofar floats. Finally, the dominant generating
mechanism for tne internal tides should be determined.

REFERENCES

Chhabra, N. K., Mooring mechanics, a comprehensive computer study,
Charles Stark Draper Laboratory report R-775, 130 pp., 1973.

Chhabra, N. K., J. M. Dahlen and M. R. Froidevaux, Mooring dynamics
experiment, determination of a verified dynamic model of the WHOI
intermediate mooring, Charles Stark Draper Laboratory report R-823,
305 pp., 1974. Taos

Fofonoff, N. P., Spectral characteristics of internal waves in the ocean,
Deep-Sea Research, supplement to 16, 59-71, 1969.

Garrett, C. and W. Munk, Space-time scales of internal waves, Geophysical
Fluid Dynamics, 2, 225-264, 1972.

Gonella, J., A rotary-component method for analyzing meteorological and
oceanographic vector time series, Deep-Sea Research, 19, 333-846, 1972.

Guthrie, R., D. Burns and 0. Smith, Current meter data report for a region
of the northeastern Pacific Ocean, Tech. Note 6110-03-74, Nav. Oceanogr.
Office, 1974.

Hendershott, M. C., Inertial oscillations of tidal period, in Progress
in Oceanography, 6, 1-27, Pergamon Press, 1973.

Knauss, J. A., Observations of internal waves of tidal period made witn
neutrally buoyant floats, J. Mar. Res., 20, 111-118, 1962.

Mooers, C.N.K., A technique for the cross-spectrum analysis of pairs of
complex-valued time series with emphasis on properties of polarized
components and rotational invariants, Deep-Sea Research, 20, 1129-
1141, 1973. oe

Patzert, W. C., K. Wyrtki and H. J. Santamore, Current measurements in the
Central North Pacific Ocean, Rep. HIC-70-31, 65 pp., Hawaii Institute
of Geophysics, 1970.

Regal, R. and C. Wunsch, M, tidal currents in the Western North Atlantic,
Deep-Sea Research, 20, 493-502, 1973.

Reid, J. L., Jr., Observations of inertial motion and internal waves,
Deep-Sea Research, 9, 283-289, 1962.

i 2
Part

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pe iene he Aa

ig

Tait ae

Vf Dani.

180°. 170° 160° 150° 140° 130° 120° 110°

of 3
Honolulu “>

180°. 170° 160° 150° 140° 130° 120° 110° w

Figure 1. Locations of current measurements

1]

DEPTH (METERS)

1000

1900

2800

3710

5300

24 HOURS

ie) 5 10 ISI2O 25
(ep fe yea Ea

ARRAY F
(CM-SEC™)

Figure 2. Example of time-dependent half-hourly current vectors

12

ENERGY DENSITY (CM* SEC™2/cph)

90 % CONFIDENCE

Legend

d =diurnal frequency
i = inertial frequency
s = semidiurnal frequency

d i

FREQUENCY (cph)

Figure 3. Energy spectra, Array B

13

ENERGY DENSITY (CM* SEC72/cph)

fo)

90 % CONFIDENCE

Legend

d = diurnal frequency
i = inertial frequency
s =semidiurnal frequency

d,i

0.I
FREQUENCY (cph)

Figure 4. Energy spectra, Array C

14

ENERGY DENSITY (CM*SEC72/cph)

100

0.1
Ol

90% CONFIDENCE

Legend

d =diurnal frequency
i = inertial frequency
s = semidiurnal frequency

d i

0.1
FREQUENCY (cph)

Figure 5. Energy spectra, Array D

15

ENERGY DENSITY (CM* SEC~*/cph)

100

0.1

90% CONFIDENCE

Ni

VEEN
wy

d =diurnal frequency
i = inertial frequency
s = semidiurnal frequency

FREQUENCY (cph)

Figure 6. Energy spectra, Array E

16

ENERGY DENSITY (CM SEC~2/cph)

100

0.1
Ol

90 % CONFIDENCE
(I000 M, ISOOM,
2800 M, 3710 M)

1

90 % CONFIDENCE
(5300 M)

d = diurnal frequency
i = inertial frequency
s = semidiurnal frequency

d i

0.1
FREQUENCY (cph)

Figure 7. Energy spectra, Array F

7

ENERGY DENSITY (CM®* SEC™2/cph)

100

0.1
Ol

90 % CONFIDENCE

Legend

d = diurnal frequency

i
s

inertial frequency
semidiurnal frequency

d i

0.1
FREQUENCY (cph)

Figure 8. Energy spectra, Array G

18

ENERGY DENSITY (CM* SEC~2/cph)

“Ol

90 % CONFIDENCE

d = diumal frequency
i = inertial frequency
s = semidiurnal frequency

d,i

0.1
FREQUENCY (cph)

Figure 9. Energy spectra, Array H

19

ENERGY DENSITY (CM? SEC~2/cph)

90% CONFIDENCE

'S0ssm | it
| 4610M y

Legend
d =diumal frequency
i = inertial frequency
s = semidiurnal frequency

d,i

0.1 1.0
FREQUENCY (cph)

Figure 10. Energy spectra, Array |

20

salyisuap ABsaue yo uolyolDA yydeq °14 eunbi4

ST
(WY) HLd3a

rrr

AON]NOZYS
W1VSIvA-LNNYS

21

ydo 280°
yudo EGO’ cceecceccece

ydo| -#—4
ydo geo" ------

(WH) HLd3a

ROTARY COEFFICIENT

Figure 12.

LEGEND —

Clockwise rotation

Anticlockwise rotation

0.1 1.0
FREQUENCY (cph)

Rotary coefficients of current records at and above 1,000 m
(The curves represent theoretical values.)

22

Clockwise rotation

Anticlockwise rotation

°

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© 00 ee 0eee0ee0000 ee ee

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FREQUENCY (cph)

,000 m

Figure 13, Rotary coefficients of current records below 1

(The curves represent theoretical values.)

23

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TABLE 2
PROBABILITY DISTRIBUTIONS OF CURRENT SPEED

ee ee
RECORD SPEED CM/SEC
0 3 6 9 12 5

PERCENT FREQUENCY

A 700 71.6 24.0 4.2 (572
2500 95.6 2.5 Wats 0.1
3750 95.7 2.6 lod
4050 93.3 3.4 16 0.3 1.4
4350 98.0 2.0
5525 92.6 6.0 1.4

B 740 50.6 Ys ee C4 1.4
1320 69.9 28.9 ot
2590 89.5 ors ere
3940 99.9 0.1
4240 99.2 0.8
4540 99.3 0,7

C 750 USo8) 24.1 2.4
2600 90.8 N32
3950 92.4 7.4 0.2
4250 90.6 9.4
4550 80.3 195 0.2

D 1000 65.8 (Ai) 3) 6.1 0.2
2810 97.9 0
3710 96.4 3.6
5210 51.8 AY ld « Weslo 3.0

E 1000 67.8 24.5 Vos 0.4
1900 98.9 oll
2910 99.4 0.6
3710 100.0
4615 94.4 6/4 0.4
5290 98.6 1.4

27

TABLE 2 (cont.)
PROBABILITY DISTRIBUTIONS OF CURRENT SPEED

RECORD a SPE FNOUUSE ciae
9 5
PERCENT FREQUENCY
F 1000 61.1 28.2 9.7 1.0
1900 97.6 2.4
2800 99.2 0.8
3710 99.1 0.8 0.1
5300 98.7 les
G 1000 52.9 S212 12.1 2.5 0.3
1890 77.9 19.8 Bae
2770 94.0 5.8 OZ
3655 82.4 17.4 0.2
H 1000 VU o) 21.0 2.0
1910 97.2 2.8
2810 98.6 1.4
3730 97.9 2.1
4620 99.8 0.2
5420 96.9 3)4l
I 1000 58.3 30.7 10.3 0.7
1920 82.9 WGoz Tot!
2835 98.6 lies OF
3720 94.0 5.9 = oll
4610 82.5 16.4 Tile
5065 81.3 18.2 0.5

RECORD

A 700

wo

Qa

2500
3750
4050
4350
5525

740
1320
2590
3940
4240
4540

750
2600
3950

4250

4550

1000
2810
3710
5210

1000
1900
2910
3710
4615
5290

1000
1900
2800
3710
5300

1000
1890
2770
3655

1000
1910
2810
3730
4620
5420

MEAN CURRENT SPEED AND DIRECTION

TABLE 3

CM/SEC
N-S

SPEED

0.68
0.13
0.05
0.24
0.14
0.10

1.09
0.82
OF52
0.26
0.53
0.43

0.78
1.00
0.94
0.73
Not

0.55
0.33
0.34
2.61

1.08
0.11
0.14
0.13
0.38
0.26

1.16
0.14
0.24
0.21
0.11

2.38
1.48
0.80
1.88

0.28
0.21
0.13
0.24
0.09
0.3]

DIRECTION

RECORD

I 1000
1920
2835
3720
4610
5065

MEAN CURRENT SPEED AND DIRECTION

TABLE 3 (cont. )

DIRECTION

CM/SEC
E-W N-S SPEE il

oti
Hole
0.17
0.31
0.89
=-1.32

-0.08
0.20
0.06

-0.54

-0.94

=0279

30

1.81
eat
0.18
0.67
1.33
1.54

092
080
071
120
133
239

TABLE 4
SPECTRAL ANALYSIS PARAMETERS

Record length: 6,144 samples, 42.7 days
Degrees of freedom for frequencies < 0.15 cph: 30

Degrees of freedom for 0.15 cph < frequencies < 0.25 cph:

Degrees of freedom for 0.25 cph < frequencies < 0.47 cph
Degrees of freedom for 0.47 cph < frequencies < 0.91 cph
Degrees of freedom for frequencies > 0.91 cph: 480

Array D, all depths

Array E, all depths

Array F, 1000 m, 1900 m, 2800 m, 3710 m

Array G, 1890 m, 2770 m, 3655 m

Array H, 1000 m, 1910 m, 3730 m, 4620 m, 5420 m
Array I, all depths

Record length: 4,096 samples, 28.4 days

Degrees of freedom for frequencies < 0.15 cph: 20
Degrees of freedom for 0.15 cph < frequencies < 0.25 cph
Degrees of freedom for 0.25 cph < frequencies < 0.47 cph
Degrees of freedom for 0.47 cph < frequencies < 0.91 cph
Degrees of freedom for frequencies > 0.91 cph: 320

Array B, 1320 m, 2590 m, 3940 m, 4240 m, 4540 m
Array C, 750m, 2600 m, 3950 m, 4250 m, 4550 m
Array F, 5300 m

3]

60
: 120
: 240

cre aa

CNO, Op-951
CNO, Op-955F
COMTHRIDFLT

CO, Canadian Maritime Forces, PAC

COMOC EANSYSPAC
COMNAVSEASYSCOM
NAVSEASYSCOM, PMS-302
COMNAVAIRSYSCOM
NAVAIRSYSCOM, AIR-540
MASWSP, ASW-11

MASWSP, ASW-111

MASWSP,, ASW-13
NAVELECSYSCOM, PME-124
NAVELECSYSCOM, PME-124TA
NAVELECSYSCOM, PME-124/20
NAVELECSYSCOM, PME-124/30
NAVELECSYSCOM, PiE-124/40
NAVELECSYSCOM, PME-124/60
CO, CHESDIVNAVFACENGCOM

CHESDIVNAVFACENGCOM, FPO-1E4 ’
NAVFACENGCOM, Code PC-2 (Dr. E. Silva)

COMNAVWEASERVCOM
OCEANAV

ONR, Code 212

ONR, Code 462

ONR, Code 480

ONR, Code 483

ONR, Code 485

ONR, AESD

NUC, Code 502

NUC, Code 6540 (R. Jones)
NUSC/NLL, Code TA
NUSC/NLL, Code SA 23

DEFRESESTABPAC (Dr. Harold Grant)

NRLe Code 3627

NRL, Code 8000

NRL, Code 9101

NRL, Code 8103

NRL, Code 8160

NRL, Code 8300
NAVSURWEAPCEN
FLEWEACEN, Pearl Harbor
FNWC, Monterey
NAVSHIPRANDCEN
COMNAVAIRDEVCEN
NAVAIRDEVCEN, Code 205
DDC

DISTRIBUTION LIST

Arthur D. Little, Inc. (Dr. G. Raisbeck)

City University of N. Y., Dept. of Earth
and Planetary Sciences (Dr. G. Neumann)

B-K Dynamics, Inc. (Mr. A. E. Fadness)

Bell Telephone Labs (Dr. T. Phillips,
Mr. R. Worley)

Bolt, Beranek & Newman, Inc.
(Mr. C. Burroughs)

General Electric Co., Electronic Systems
Div. (Mr. H. Burkart)

Dir., Marine Physical Lab., SIO

MRP, SIO (Dr. G. B. Morris

Planning Systems, Inc. (Dr. L. P. Solomon)

RAFF Associates, Inc. (Dr. J. I. Bowen)

TRW Systems Group (Mr. R. T. Brown)

Tetra Tech., Inc. (Mr. C. Dabney)

Texas A&M Univ. (Mr. J. D. Cochrane)

Texas Instruments, Inc. (Mr. A. Kirst)

TRACOR, Inc. (Mr. J. T. Gottwald)

Underwater Systems, Inc. (Dr. M. Weinstein)

Gulf Universities Research Consortium
(Mr. Ian Miller)

Lamont-Doherty Geological Observatory,
Columbia Univ. (Dr. F. Malone)

Lamont-Doherty Geological Observatory,
Columbia Univ. (Dr. T. Pochapsky)

WHOI (Dr. E. E. Hays)VOV 1 1 1975

WHOI (Dr. T. Sanford)

WHOI (Mr. R. Walden)

University of California, SIO (Dr. J. Reid,
Dr. K. Kenyon)

University of Miami (Dr. S. C. Daubin)

Western Electric Co. (Mr. G. Hammond)

University of Washington, Dept. of
Oceanography (Dr. B. Taft)

Massachusetts Institute of Technology,
Dept. of Earth and Planetary Physics
(Dr. C. Wunsch)

CIVENGRLAB (Mr. C. Nordel1)
ENVPRESDSCHFAC (Dr. T. Laevastu)
CNA (Capt. C. Woods)

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