the marine light - whoas at mblwhoi library
TRANSCRIPT
WHOI-93-33UOP Report 93-4
WHól- £1"3 -33
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The Marine Light - Mixed Layer ExperimentCruise and Data Report
R/V Endeavor
Cruise EN-224, Mooring Deployment, 27 April-1 May 1991
Cruise EN-227, Mooring Recovery, 5-23 September 1991
Albert J. Plueddemann
Robert A. Weller
Thomas D. Dickey
John Marra
George H. Tupper
Bryan S. WayWilliam M. Ostrom
Paul R. Bouchard
Andrea L. OienNancy R. Galbraith
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Upper Ocean Processes GroupWoods Hole Oceanographic Institution
Woods Hole, Massachusetts 02543
May 1993
Technical Report
Funding was provided by the Offce of Naval Research under Contract N00014-89-J-1683.
Reproduction in whole or in part is permitted for any purpose of theUnited States Government. This report should be cited as:
Woods Hole Oceanog. Inst. Tech. Rept., WHOI-93-33.
Approved for publication; distribution unlimited.
Approved for Distribution:
~,~ L'1~---/ James Luyten, Chair
Department of Physical Oceanography
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WHOI-93-33UOP Report 93-4
The Marine Light - Mixed Layer ExperimentCruise and Data Report
R/V Endeavor
Cruise EN-224, Mooring Deployment, 27 April-1 May 1991Cruise EN-227, Mooring Recovery, 5-23 September 1991
Albert J. Plueddemann
Robert A. Weller
Thomas D. Dickey
John Marra
George H. Tupper
Bryan S. Way
Wiliam M. OstromPaul R. Bouchard
Andrea L. Oien
Nancy R. Galbraith
Upper Ocean Processes GroupWoods Hole Oceanographic Institution
Woods Hole, Massachusetts 02543
May 1993
Technical Report
Funding was provided by the Offce of Naval Research under Contract N00014-89-J-1683.
Reproduction in whole or in par is permitted for any purpose of theUnited States Government. This report should be cited as:
Woods Hole Oceanog. Inst. Tech. Rept., WHOI-93-33.
Approved for publication; distribution unlimited.
Approved for Distribution:
~~Á~,James Luyten, Chair
Department of Physical Oceanography
Abstract
The Marne Light-Mixed Layer experiment took place in the sub-Arctic North
Atlantic ocean, approximately 275 miles south of Reykjavik, Iceland. The field
program included a central surface mooring to document the temporal evolution of
physical, biological and optical properties. The surface mooring was deployed at
approximately 59°N, 21°W on 29 April 1991 and recovered on 6 September 1991.
The Upper Ocean Processes Group of the Woods Hole Oceanographic Institution
was responsible for design, preparation, deployment, and recovery of the mooring.
The Group's contribution to the field measurements included four different types
of sensors: a meteorological observation package on the surface buoy, a string of
15 temperature sensors along the mooring line, an acoustic Doppler current pro-
fier, and four instruments for measuring mooring tension and accelerations. The
observations obtained from the mooring are sufcient to describe the air-sea fluxes
and the local physical response to surface forcing. The objective in the analysis
phase wil be to determine the factors controllng this physical response and to
work towards an understanding of the links among physical, biological, and optical
processes. This report describes the deployment and recovery of the mooring, the
meteorological data, and the subsurface temperature and current data.
.
Table of Contents
Abstract .......... . . . . . . . . . . . . . . . . . . . . . . . . . . .
List of Tables and Figures . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 Introduction ............. . . . . . . . . . . . . . . . . . . . .
2 Mooring Deployment and Recovery.
2.1
2.2
2.3
2.4
. . . . . . . . . . . . . . . . . . . .
The MLML Mooring . . . . . . . . . . . . . . . . . . . . . . .
Instrumentation . . . . . . . . . . . . . . . . . . . . . . . . .
Deployment . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Data Presentation .
3.1
3.2
3.3
3.4
. . . . . . . . . . . . . . . . . . . .
Meteorological Variables. . . . . . . . . . . . . . . . . . . . .
Air-Sea Fluxes . . . . . . . . . . . . . . . . . . . . . . . . .
Upper-Ocean Temperature . . . . . . . . . . . . . . . . . . .
Upper-Ocean Currents. . . . . . . . . . . . . . . . . . . . . .
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix 1: Cruise Participants . . . . . . . . . . . . . . . . . . . . . . . .
Appendix 2: Chronological Log. . . . . . . . . . . . . . . . . . . . . . . . .
11
ii
1
3
3
6
13
18
21
21
26
28
31
107
108
110
111
List of Figures
1 The MLML mooring site. 4
2 The 1991 MLML mooring . 5
3 The buoy tower 10
4 Pre-deployment CTD cast . 14
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Mooring anchor survey . . 16
17
19
35
39
43
52
61
62
71
80
89
98
Surface buoy positions in May .
Pre-recovery CTD cast . . . . .
Meteorological variables from the two VA WRs .
Differences between meteorological variables
Best available meteorological vaiables
Air-sea fluxes from bulk formulae. . .
Eight-hour mean temperatures versus depth.
Sub-surface temperature time series
Contours of sub-surface temperature
Velocity time series, East component . . . . . . . . . . . . . . . .' .
Velocity time series, North component
Sub-surface velocity vectors at selected depths
Pre-deployment buoy spin . . . . . . . . . . . . 116
ii
List of Tables
1
2
3
4
5
6
VA WR sensor specifications
VA WR sensor positions ..
Statistics of VA WR differences
STL data recovery . . . .
Calibration Adjustments .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . .
Temperature and current depth grid
iv
. . . . . . . . . . . . . . . . . .
8
9
22
28
31
32
¡,
-f
1 Introduction
The Marine Light-Mixed Layer (MLML) field program was conceived as a part
of the Marine Bioluminescence and Upper Ocean Physics Accelerated Research
Initiative sponsored by the Offce of Naval Research, and was predicated on the
concept that temporal and spatial vaiabilty in the marne ecosystem are intimately
related to physical processes. The Upper Ocean Processes Group (UOPG) at WHOI
took responsibilty for the design, deployment, and recovery of an instrumented
surface mooring which served as the focal point for the field program. The long-term
goal of our work in the MLML program is to develop an improved understanding of
upper ocean physical processes and the links among physical, biological, and optical
processes. In particular, we are interested in the horizontal and vertical structure
of density and velocity in the upper ocean and the response of those fields to heat
and momentum fluxes at the sea surface.
Ii .
From the MLML mooring we have obtained observations suffcient to describe
the air-sea fluxes and the local physical response to surface forcing. During the
analysis phase, effort wil be concentrated on determination of the factors control-
ling this physical response and consideration of of the links between the physical,
and bio-optical components of the seasonal cycle in the high-latitude North At-
lantic. The primary objectives of this work are: (1) to document the upper ocean
response to surface forcing and determine the controllng factors in the restratifi-
cation and mixed layer deepening processes, (2) to assess the relationship between
physical forcing and the bio-optical properties of the water column, in particular
the relationship between the onset of restratification and the spring bloom of phy-
toplankton, and (3) to determine the extent to which bio-optical properties can
be predicted given knowledge of the physical forcing and to consider the feedback
between physical and bio-optical properties in the development of a mixed layer
1
modeL. These objectives wil be addressed in close collaboration with the other
MLML principal investigators.
In order to understand the link between physical forcing and bio-optical var-
ability we must first know the surface forcing. This forcing consists of wind stress
and the sensible, latent, and radiative heat fluxes, which can be computed from
the meteorological variables recorded on the mooring using bulk aerodynamic for-
mulae. Given this record of surface forcing, we wish to document the upper ocean
response and determine the controllng factors in the restratification and deepening
processes. The deep winter mixed layer at the MLML site (Robinson et ai., 1979;
Levitus, 1982) results from convective mixing due to surface heat loss combined with
strong wind forcing. Of particular interest is the spring restratification process, pre-
sumably driven by net heating during periods of weak wind forcing. Several studies
have been devoted to the seasonal evolution of temperature and current structures
in the upper ocean at temperate latitudes (e.g., Briscoe and Weller, 1984, as par
of the LOng Term Upper Ocean Study experiment, and Dickey et ai., 1991, as par
of the Biowatt experiment). However, there have been few intensive studies of the
springtime transition of the mixed layer and restratification of the upper water col-
umn and even fewer comparable observational programs at latitudes higher than
45°N. The temperature and velocity measurements from the MLML mooring doc-
ument the upper ocean response at a high latitude site with unprecedented vertical
(20 m intervals over the upper 300 m) and temporal (1-15 min) resolution.
This report describes the deployment and recovery of the mooring, the meteo-
rological data, and the subsurface temperature and current data.
2
2 Mooring Deployment and Recovery
2.1 The MLML Mooring
The MLML experimental site (Figure 1) is in a region characterized by high
winds, large waves, and strong currents. This severe environment represented a
challenge to our abilty to make detailed measurements of local atmospheric forcing
and the biological, optical, and physical variabilty of the upper ocean. The process
of meeting this challenge began in 1989 with the design and deployment of the
MLML pilot mooring. The pilot mooring remained on station for 10 weeks, after
which the failure of a component in the mooring line (a pear-ring link) caused the
surface buoy to go adrift and the mooring line to sink to the bottom. The surface
buoy was recovered soon afterwards and the sub-surface portion of the mooring
was recovered in July of 1990. Analysis of data from the buoy and consideration
of the mooring design indicated that both the static tension and cyclic loading on
the mooring hardware were higher than anticipated, resulting in the component
failure. The 1991 mooring was designed both to minimize the static tension along
the mooring line and to survive peak tensions in excess of those observed on the
pilot mooring.
Benefiting from extensive evaluation of the performance of the pilot mooring,
the 1991 MLML mooring (Figure 2) proved to be a reliable severe-environment plat-
form from which 131 days of surface and sub-surface data were collected between
29 April and 6 September of 1991. The critical design elements of the 1991 moor-
ing included upgraded hardware designed to survive cyclic loading, an increase in
scope (the ratio of the slack length of the mooring to the water depth) to minimize
static tension, and a compliant element which allowed the mooring to be "tuned"
so that the resonant frequency was outside of the surace wave band. The 1991
3
35W65N
30W 20W lOW o5N
60N
~"b
~ ON
Q"
2.00m .-c-.00_:o':-..'
.\:.......50N35W 30W
ONo
Figure 1: The MLML mooring site at 59.5°N, 21°W is shown along with a grid rep-resenting the shipboard survey region. The site at 59°N, 19°W is Ocean WeatherStation India (OSWI) were the data of Lambert and Hebenstreit (1985) were col-lected.
4
10m
20 m
30m
40m
45 m
50 m
14 294 54m15 310
50 m
70 m
90 m
2100 m
3 meter Discus Buoy
with 2 VAWRs and
Argos Telemetry
5.57 M 3/4" CHAIN
MVMS5.52 M 1/2" WIRE
BOMS7.54 M 1/2" WIRE
MVMS5.52 M 1/2" WIRE
BOMS2.2 M 3/4" CHAIN
MOORDEX3.47 M 3/4" CHAIN
MVMS
ADCP4.07 M 3/4" CHAIN
BOMS7.5 M 1/2" WIRE
MVMS17.1 M 1/2" WIRE
MVMS510M7/15"WIRE500 M 3/8" WIRE
500 M 3/8" WIRE
500 M 3/8" WIRE
Engineering Instrument100 M 3/8" WIRE
530 M 7/8" NYLON SPLICED TO
570 M 1-1/8" POLYPROPYLENE
(2) 17" GLASS BALLS
Engineering Instrument(80) 17" GLASS BALLS ON 1/2" CHAIN
Figure 2: Schematic diagram of the 1991 MLML surface moonng. Intruentacronyms are described in the text.
5
mooring was of compound (wire, nylon, and polypropylene) construction, using a
10 foot diameter discus as a surface float. The scope of the mooring was 1.25. The
mooring used the so-called "inverse catenar" design, wherein a section of nega-
tively buoyant nylon is spliced to a section of positively buoyant polypropylene just
above the flotation balls. At low current speeds, the nylonjpolypro section takes
on an "S" shape (Figure 2). This allows scopes significantly greater than one while
eliminating the possible tangling problem of slack line hanging down and fouling
lower components in low currents.
2.2 Instrumentation
Our responsibilty for instrumentation on the mooring included the meteoro-
logical measurements and the current and temperature measurements below about
100 m depth. Instrumentation prepared by the UOPG included two Vector Aver-
aging Wind Recorders (VAWR), 15 Submersible Temperature Loggers (STL), an
Acoustic Doppler Current Profiler (ADCP), three engineering instruments, and a
tensiometer.
Complementar instrumentation in the upper 100 m deployed by other MLML
investigators included five Multi-Variable Moored Systems (MVMSs; T. Dickey,
University of South~rn California (USC) and J. Mara, Lamont-Doherty Geologi-
cal Observatory (LDGO)), three Bio-Optical Moored Systems (BOMSj R. Smith,
University of California, Santa Barbara (UCSB)), and a moored bioluminescence
sensor (MOORDEX; J. Case, UCSB). The MVMSs provide point measurements
of horizontal velocity and temperature in addition to bio-optical variables, and we
include those velocity and temperature measurements in this report. No other data
from the USC, LDGO, or UCSB instruments are included.
6
. Instrumentation on the surface buoy included two VA WRs, an engineering in-
strument for sampling tension and vertical acceleration, a BOMS, and a dissolved
oxygen sensor. A communications module was included to allow the VAWR to trans-
mit meteorological data via ARGOS satellte. Two ARGOS antennas were mounted
on the buoy tower. Each transmitted data from one of the VA WRs and also provided
buoy position data. Another ARGOS transmitter in the buoy well was connected to
a flat, deck-mounted antenna. Besides telemetering instantaneous values of buoy
tension and battery voltage, this transmitter system was meant to be the backup
buoy location device if heavy seas broke off the tower-mounted antennas. An addi-
tional backup ARGOS transmitter was mounted on one leg of the three-legged bridle
below the buoy. It was mounted upside down and activated by a mercury switch in
the event that the mooring broke at or near the bridle and the buoy turned upside
down.
Two engineering instruments were placed on the mooring, one at a position 100
meters above the wire/nylon interface and the other just above the glass bal section.
They measured tension, inclination, temperature and depth. One char-recording
tensiometer was placed between the glass bals and the release.
One VA WR was scheduled for deployment on the MLML buoy by Marra. To
ensure that surface forcing data was collected successfully, we proposed a second
VAWR for installation on the buoy. In addition to the ARGOS telemetry, the
VAWRs recorded data internally at 15 min intervals. Both VAWRs were outfit-
ted with sensors for the measurement of wind speed (WS), wind direction (WD),
sea-surace temperature (SST), air temperature (AT), incoming shortwave radiation
(SW), barometric pressure (BP), relative humidity (RH), and incoming longwave
radiation (LW). The sensor specifications for the VAWR are given in Table 1.
7
Parameter Sensor Range Comments
Wind Speed Gil 3-cup 0.2-50 m/s Vector-averagigAnemometerR.M. YoungModel12170C100 cm/rev
Wind Direction Integr Vane 0-360° Vector-averagigwI Vane followerWHOI I EG&G
Shon wave Pyometer 0-1400 wans/m2 Average systemRadiation Eppley
Model: 8-48
Long wave Pyrgeometer 0-700 watts/m2 Average systemRadiation Model: PIR
Relative Humidity Varble 0-100% 3.5 sec sampleDielectrcConductorVaisaa Humicap
Barmetrc Quam Crysta 0-1034 mb 2.5 see samplePressure Digiqua (Burt taen midway
Parscientific thugh avg. period)Model: 215
Sea Temperatu Thermstor -5 to +30°C 1/2 tie averge.Therometres Meaured durg fit4K (g 25° C hal of avg. period.
Ai Temperatu Thermstor -10 to +35° C 1/2 tie avergeYellow Springs Meaured durg 2nd#4034 hal of avg. period.5K(g 25°C
Table 1: Sensor specifications for the Vector Averaging Wind Recorder (VAWR).
8
sensor height (m) separation (m)
SW /LW 3.6 0.1
WS 3.5 1.1
WD 3.2 1.1
AT/RH 2.8 0.2BP 2.5 0.6SST (SN 184) -1.0SST (SN 706) -2.0
Table 2: Height above the buoy waterline is shown for sensors on the two MLMLVAWRs. Horizontal separation is given for sensors at the same height on bothVAWRs.
All of the VAWR sensors, except SST, were attached to the discus buoy tower.
The two SST sensors were attached to the buoy bridle at depths of approximately
1 m and 2 m. The buoy tower was a tripod design, with the distance between
legs tapering from about 2.5 m at the buoy deck to 0.6 m at the upper platform
(Figure 3).
The two VAWR pressure housings were supported by an intermediate platform
at about 1.5 m height, and the sensors were clustered around the upper platform
at about 3 m height. Sensor positions with respect to the water line are given in
Table 2.
All of the meteorological sensors were calibrated both before and after the
experiment and "ground truth" measurements were made prior to deployment and
recovery of the buoy. The calibrations are discussed in Section 3 and the chronology
of the ground truth testing is given in Appendix 2.
Through the efforts of other MLML investigators, the upper 100 meters of the
mooring was instrumented with five MVMSs, three BOMS, and the MOORDEX
9
swfLW SW/LW
1.5 m
WS WS
WD WD
1.2 m
BUOY 'DECK
Figure 3: Schematic diagram of the meteorological sensor tower on the 1991 MLMLbuoy. The buoy deck is approximately 0.4 m above the water line. Sensor acronymsare described in the text.
10
(Figure 2). The MVMSs were deployed at 10 m, 30 m, 50 m, 70 m and 90 m depth
and the BOMS at at 20 m, 40 m and 60 m depth. These instruments provided
temperature data at 10 m intervas (except at 80 m) and currents at 20 m intervas
between 10 m and 90 m depth. UOPG instrumentation (15 temperature loggers
and an ADCP) was deployed to supplement these measurements and extend the
range of current and temperature observations to cover the full range of expected
mixed layer depths.
The fifteen Submersible Temperature Loggers (STLs) were acquired from Richard
Brancker Research Ltd. in Canada. These are self-contained instruments which
record internally to solid state memory. Ten of the loggers were Model XL-I00 and
five were Model XX-I05. The two models differ in their temperature precision and
pressure case design. The XX-I05 has increased precision compared to the XL:.I00,
but over a reduced temperature range. The XL-lOO pressure case is rated to 1000 m
and uses an externally mounted thermistor, while the XX-105 pressure case is rated
to 7500 m and has the thermistor mounted internally. We worked with the manu-
facturer to modify the XL-I00 and XX-I05 units to have similar temperature range
and precision. For the XL-I00, the original YSI 44203 thermistor was replaced by a
YSI 44033, resulting in a precision of 0.012°C over a range of -5 to 30°C. The resis-
tors of the XX-I05 bridge circuit were chosen to give a nominal precision of 0.004°C
over a range of 3.5 to 33°C (the actual precision vares slightly with temperature
from 0.002° at the low end to 0.007° at the high end). The stated accuracy of the
STLs is O.OI°C. During calibration tests at WHOI we found the XL-lOO units met
this specification, while the XX-I05 units typically performed somewhat better (e.g.
0.005°C).
The STLs were attached to the mooring wire using a hinge-type clamp which
was tightened around the wire. One STL was placed at 80 m depth to continue the
10 m temperature spacing down to 90 m. The remaining 14 sensors were placed at
11
16 m intervals between 102 m and 310 m depth to match the center points of the
averaged ADCP depth cells (see explanation below).
The ADCP was a 150 kHz, self-contained unit manufactured by RD Instru-
ments in San Diego. Outfitted with pendulum tilt sensors, a flux gate compass,
and 20 Mbytes of solid state memory, the instrument was clamped to a load cage
with the transducers pointing downwards from a depth of 54 m. Four transduc-
ers transmitted acoustic energy along narrow beams (approximately 40 half-power
beam width) insonifying a volume of fluid determined by the beam width, the du-
ration of the acoustic pulse, and the distance from the transducers. Backscattered
energy from the insonified volume arrives at the transducers with a Doppler shift
proportional to the average speed of the scatterers in the volume. To the extent
that the scatterers are advected with the fluid, Doppler shifts estimated at suc-
cessive times after transmission provide a profile of water velocity as a function of
distance along the beam.
For MLML, the ADCP was configured to send out pulsed transmissions at one
second intervals for a period of 60 s. This sequence of 60 transmissions, called an
ensemble, was repeated at 15 min intervals. Values of velocity in earth coordinates,
echo amplitude, and data quality parameters for each beam, along with heading,
tit, and temperature data were averaged for each ensemble and recorded to mem-
ory. The precision of velocity estimates from ADCPs depends principally on the
operating frequency and the pulse length. For MLML the estimated precision of
the 15 min average horizontal velocities is about 2 cm/s.
The backscattered signal from each transmission is processed over equally
spaced time intervals corresponding to successively deeper insonified volumes known
as depth cells (the depth cell length is the vertical component of the insonified vol-
ume). For MLML, data were processed over time intervals corresponding to a 8 m
12
depth cell, while the nominal depth resolution of the transmitted pulse was 16 m.
Thus, the data were oversampled in depth and successive depth cells are not inde-
pendent. Forty depth cells were recorded for each transmission, giving a profiing
interva of 320 m. The first depth cell recorded was centered at a depth of 66 m
and the center of the last cell was at a depth of 378 m. Prior to analysis, the data
is usually averaged over two depth cells so that the sampling interva matches the
16 m depth resolution. Considering the two-cell average ADCP data we see that
the 102 m STL is at the center of the third averaged cell, the 118 m STL at the
center of the fourth averaged cell, etc., down to the 310 m STL which is at the
center of the 16th averaged cell.
2.3 Deploymenti\ .
The ship used for the deployment cruise was the R/V ENDEAVOR, operated by
the University of Rhode Island, which sailed out of Reykjavik, Iceland for the MLML
experiment. The UOPG scientific party arrived in Reykjavik on 22 April 1991 to
begin cruise preparations. The ENDEAVOR sailed at mid-day on Saturday, 27 April
1991, arriving at the launch site approximately 275 miles south of Reykjavik at
0420 Z, 29 ApriL. Winds were out of the northeast at 15 gusting to 25 knots. The
sea state was 5, with an 8-foot swell, as estimated by the bridge. A CTD was taken
to 275 meters at 0500 Z to document pre-deployment vertical structure (Figure 4).
The acoustic release lowering was done to 750 meters.
The mooring launch commenced after breakfast on 29 April, with the entire
launch operation taking just under eight hours to complete. The anchor went over
the side at 1542:30 Z and hit bottom at 1603:52, giving an average descent rate
of 132 meters per minute. At the time of anchor launch, GPS was down, so we
elected to do the acoustic survey of anchor position using Loran-C. Later, when
13
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Figure 4: CTD cast taken from R/V ENDEAVOR on 29 April 1992, just prior todeployment of the MLML mooring
14
GPS was back up, we calculated the offset between GPS and Loran-C. The Loran-
C position was 0.44 Nautical miles away and bearng 0060 from GPS position. The
fial position of the anchor was calculated using this offset (Figure 5), giving 590
35.61'N latitude, 200 57.85'W longitude. The water depth at the anchor site was
determined to be 2822 m. After the anchor surey, the ship approached the surface
buoy to log its position and take some video footage. The Buoy position was about
1.2 miles northeast of the anchor.
At 1758 Z on 29 April we launched a Metocean drifter buoy number 14314,
given to us by the U. S. Navy (Naval Oceanographic Command) at Keflavik, Ice-
land. Position of the drifter launch was 590 34.6'N, 200 57.2'W. Having completed
deployment operations, the ENDEAVOR left the MLML site and returned to Reyk-
javik on 1 May 1991.
There was interest in documenting the watch circle of the large-scope MLML
mooring, which would also aid in determining the safe approach distance to the
anchor position for ships working in the area. From the water depth and a scope
of 1.25 the horizontal excursion for the buoy is estimated at 2.1 km (1.1 n-mi).
However, since the scope is defined using the slack length of the mooring, we must
account for the stretch of the synthetic components under load. Assuming that
the 1300 m of nylon and polypropylene stretches 15% gives a maximum horizontal
excursion to 4.7 km (2.5 n-mi). Buoy positions determined from ARGOS telemetry
for the period 1-9 May are shown in Figure 6. These positions have accuracy of
about 350 m (0.2 n-mi). The plot shows that the buoy is typically found between
the slack-length excursion and the maximum excursion.
15
r.Q;:E:E-~..::E-~ozc:r.r.~ør.Q
.¡
20 DEG.59'W.
DEGREES WEST LONGITUDE58' 57' 56' 55' 54' 53'
59 DEG38'N.
SHI'S POSITION16S7Z .
37'
36' 17SSZ RANGE ARC(LORAN-C)
16S7Z RANGE ARC(LORAN-C)
.SHIP'S POSITION1727Z
~GPSANCHORPOSITIO
35' 1727Z RANGE ARC(LRA-C)
.SHI'S POSmON17SSZ
34'
Figure 5: The MLML-91 mooring anchor position, determined from Loran-C fixeswhile GPS was down, and later adjusted using GPS (see text). The position of theanchor was determined to be 590 35.6lN, 200 57.85'W.
16
20 DEG.59'W.
DEGREES WEST LONGITUDE58' 57' 56' 55' 54' 53'
59 DEG38'N.
35'
37' e8
~ e7Q;: e9E-~E-~..::E-ei0 36'Z e3l"~ e4~ (!ei~ GPS~ ANCHORQ POSITION
ONE MlERADIUS
TWO MILERADIUS
34'
Figure 6: MLML-91 buoy positions from ARGOS for the period 1-9 May relative tothe estimated anchor position.
17
2.4 Recovery
The R/V ENDEAVOR sailed from Reykjavik, Iceland for the mooring recovery
at 1030 Z, 5 September 1991. The weather forecast called for flat seas for several
days, an unusual occurrence at the MLML site, but very good news for the mooring
recovery team. A cal was made to WHOI just before the ship sailed to check
the VA WR ARGOS telemetry data from the mooring, confrming that the highest
barometric pressure and lowest wind speeds of the entire experimental record were
being observed.
On the morning of 6 September ENDEAVOR arrived at the mooring site. En-
route to the mooring in calm seas (sea state 1), the buoy was seen on radar at a
distance of six miles. At 1100 Z, the buoy was sighted visually at three miles. The
ENDEAVOR hove-to 1/4 mile downwind of the buoy for a half-hour of meteorological
ground truth measurements. These data appear in Appendix 2. At least a hun-
dred seagulls were seen around the buoy, mostly swimming, but some perched on
the deck with one sitting on top of the BOMS sensor. The deck of the buoy was
covered with a greenish algae/weed growth, indicating it had been awash a good
bit. Sensors appeared to be undamaged and looked like new. A CTD was taken to
400 meters before the mooring recovery (Figure 7).
The acoustic release was fired at 1250 Z on 6 September and the mooring began
its ascent. The recovery went smoothly, with the mooring and all instruments
aboard by 1800 Z. Recovery was slowed by the TSE winch not having enough drum
capacity to hold all of the mooring; operations had to be stopped midway through
to offspool wire so that the rest of the mooring could be hauled in.
The condition of al instruments on recovery was good, with two exceptions.
The MVMS at 10 meters was covered with a black, oily fotÙing. The transmissome-
ter of this instrument was missing, with broken cable hanging loose, and the MVMS
18
i:G;i I II '! i~ ; I! II 1+1... ~+--t--t-H . 1-" J: I i I I I! I.",~ I ii I i 'i I I i i I I i~. I i,i i i I.
r¡I I I: """ tl l ii I . i .... i ¡ i ! i I
--r-i 1-1 . ~ ~mi 1--1¡ i i I I I Iv'" j i ¡ ! I r.
f-+.--'--f ! ,r~rlJIl-( .~.~~~. ~'i : I I ~ ki' ,i..t_lI ¡ ¡ i I i i I I! i i Iii ¡ .1 ii ! i I i ¡i. ¡ I ., -l----.,L-J-_l _I L~-~---i---_l""': ! I ! I I ri ! ! ! I I, i I i I' I ¡ii i ! i ItI~' ¡ " I" i I iti i, I i !' I ii : ! i !! i I . I i I I ¡
~ t -¡---. i --¡---¡---ttt-i-t-t---l--t,.-¡--¡. i ¡ II i i ¡ I I I i I. i I I ¡ I¡- i ! If' ! : i I I I I! I I i
i i ;1\.l-I'-ï-nit-ir~. L j.i.-.i'-J~tt.. ,..' . . +L---4Ji i'i .. Ii', i I I i i I -ti ~! ii"., ~ III i .1 i i
1/~~t\1 I i I . ..;t.+...-. ¡ i i I Ir" -i-.TT-r-i-rr.-ri--rl'-T--1IlQ.I'I I!! I I' i r -l...L 1.. I I i~ I I I i i I I Ii. '-'. I l~ I i i I i I i 1--1-..--JOJ i . . ... -a:a:a:C5
W HI d3(1
C5'I.InM
oo"o
~§ø:
..:I..:I!-a:
!-..a:C/ !-..
a:C/
o.
Po:Ii:!-
a:NInM
..ti;:'1
ø:r-NNZi:~
lS
C5C5'I
Figure 7: CTD cast taken from R/V ENDEAVOR on 6 September 1992, just priorto recovery of. the MLML mooring
19
at 50 meters had a broken Oxygen probe. The Argos transmitter on the buoy bridle
was severely corroded in the mid-section of its pressure case.. It was hypothesized
that this was due to the lack of a neoprene pad on the bottom mounting bracket
base plate, allowing the aluminum case to directly touch the bracket. The mooring
hardware and wire rope looked in good shape. None of the STL brackets showed
any signs of slippage on the wire rope. The nylon had three small wuzzles all within
100 m of the nylonjpolypro splice. The wuzzles may have been caused by the nylon
going slack and then throwing a loop and tightening itself on the loop.
The ship left the MLML site after recovery operations were complete, arriv-
ing outside Reykjavik harbor early on 8 September. Personnel from LDGO and
Mark Grosenbaugh from WHOI departed on the pilot boat, while the rest of the
science party remained onboard, sailing south to track down and recover the surface
float from the North-West mooring of the Subduction Experiment array which had
gone adrift. After recovering the drifting portion of the Subduction mooring on 15
September, ENDEAVOR arrived at WHOI on 23 September, 1992.
20
3 Data Presentation
The surface meteorological varables, air-sea fluxes, upper ocean temperatures,
and upper ocean currents observed from the MLML mooring are presented in this
section. The observations come primarly from the UOPG instruments on the moor-
ing (two VAWRs, the STLs, and the ADCP), but measurements of currents and
temperature from the MVMSs are also included. The principal means of presenta-
tion is a series of figures and tables which are described in the text and presented
at the end of the section.
3.1 Meteorological Variables
The VA WR data tap~s were read for each instrument resulting in files con-
taining time and eight meteorological vaiables: Wind speed (WS), wind direction
(WD), sea-surace temperature (SST), air temperature (AT), incoming shortwave
radiation (SW), barometric pressure (BP), relative humidity (RH), and incoming
longwave radiation (LW). The longwave radiation measurements from MLML are
discussed in Dickey et al. (1993) and wil not be presented here.
A small number of obviously bad points (less than 0.2% of the samples) were
edited out by hand and replaced by linearly interpolated values. In order to elim-
inate data from periods prior to deployment and after recovery of the mooring, a
de-facto definition of MLML-91 start and end dates was made. The resulting files
had 12384 15 min samples starting on 4/30/91 00:15 (yearday 120.0052) and ending
on 9/05/91 23:45 (yearday 248.9948).
Time series of meteorological variables recorded by the two VA WRs on the
MLML mooring are shown in four sections in Figure 8a-d. The data presented are
at the 15 min intervals recorded by the instrument, with no additional averaging
21
variable mean difference std dev
WS (m/s) -0.03 (0.4%) 0.21 (4.8%)WD (0) -4.60 3.74SST _1 (OC) +0.027 0.050SST-2 (OC) -0.036 0.467AT (OC) +0.002 0.083SW (W 1m2) -3.15 (1.8%) 5.16 (11 %)
BP (mb) -0.22 0.18RH (%) -1.11 0.81
Table 3: Statistics of the difference between measurements of like vaiables for thetwo VA WRs are shown. Statistics of the difference expressed as a percent of thetwo-sensor mean are also shown for some varables. SST _1 is the period of goodperformance, SST -2 the period of bad performance.
applied. Observations from VA WR Serial Number ('SN) 184 are shown as a solid
line, observations from SN 706 as a dashed line. The extent to which the two lines
are indistinguishable is a fist-order indication of the quality of the measurements.
The only discrepancies discernible in these plots are in the relative humidity and
the sea surface temperature.
Time series of the differences (SN 184 - SN 706) between varables observed
by the two VA WRs are shown in four sections in Figure 9a-d. These time se-
ries, and their statistics (Table 3), allowed evaluation of VAWR performance. The
best performing sensor for each varable was chosen to form the "best available"
meteorological data from which to compute air-sea fluxes.
Estimates of the accuracy (difference between observed and true value), pre-
cision (repeatability of successive readings), and resolution (smallest change de-
tectable by the sensor) for the VAWR are presented by Weller et aI., 1990. Values
from their Table 3 are quoted in the discussion below. The sensors on the two
22
VA WRs were in close enough proximity that we expected experiment-long mean
differences greater than the sensor accuracy to be indicative of calibration biases.
The observed differences at 15 min intervals can be effected by true small-scale
spatial varability in the measured quantity. Thus, it would be unlikely that the
standard deviation of the differences would be as small as the sensor precision (the
precision is the "best case" repeatability under controlled conditions). Stil, we ex-
pected the standard deviation to be near the estimated sensor accuracy for most
vaiables.
The wind speed difference had a mean of 0.03 mls and a standard deviation of
0.2 m/s. The standard deviation of the difference expressed in terms of a percent
of the wind speed was 5%. The wind direction difference had a mean of 50 and
a standard deviation of 40. This compares with an estimated accuracy of 2% for
wind speed and 30 for wind direction. We concluded that the wind sensors were
performing within tolerable bounds, although there was probably a small compass.
calibration bias resulting in the mean difference two degrees larger than the esti-
mated accuracy. From the information avalable, it was not possible to know which
sensor had the larger directional error. Instead we accepted a directional uncer-
tainty of about 50 and chose SN 184 for wind speed and direction based on its more
"reasonable" performance during the strong wind event on 20-21 May.
Sea surface temperature was the variable with the most obvious measurement
problem. It can be seen from the plots that the difference is small up until about
21 May and after 1 August. During this "good" period, the mean and standard
deviation of the difference are 0.030 and 0.050, respectively. The pre and post
deployment calibrations indicated both sensors to be accurate within 0.0050 or less,
quite reasonable given the estimated accuracy of 0.0040. The observed difference
statistics about an order of magnitude larger than the estimated accuracy may be
explained by the fact that the two sensors were separated by 1 m in the vertical.
23
The vertical variability of temperature near the sea surface presumably contributed
to observed differences on the order of 0.010.
During the "bad" period between 22 May and 31 July, the standard deviation
of the difference increased to 0.50 and peak differences of of up to 20 were observed.
A sensor malfunction of some type is indicated, but the problem was transient in
the data and did not show up the post deployment calibrations or electronics checks.
Both SN 184 and 706 appeared to be effected. As a result it was not possible to
determine the cause of the problem or to isolate the problem to a single sensor.
Instead, we chose the SST from SN 706, which showed fewer sharp jumps than
SN 184, and used the temperature from the MVMS at 10 m as a benchmark for
correction.
It was found that with two ad-hoc adjustments to the SN 706 SST, we could get
good agreement with the 10 m temperature. The first adjustment was made on day
151 where SST mysteriously jumps down by about a degree, and the second on day
168 where it jumps back up again. After several trials the fial adjustments were
b.Ti = +0.920 between yearday 151.1927 and 151.3281, and b.T2 = -0.64 between
yearday = 168.3906 and 168.5990. These adjustments were done after the initial
calibration adjustments (described in Section 3.3) were completed. This adjusted
record from SN 706 was used for SST.
Air temperature showed a mean difference of 0.002°e and a standard deviation
of 0.08°e. The observed mean difference indicates no biasing problems, given the
estimated accuracy of 0.008°e. Similar to the situation for SST during its period of
good performance, the standard deviation is significantly larger than the estimated
accuracy. Simple regressions were used without success in an attempt to fid a
relationship between the air temperature difference, low wind speed, and high in-
solation. There was no evidence of electronics problems for either sensor, and the
24
pre and post deployment calibrations for both sensors were within the estimated
accuracy. Under the assumption that the observed differences were the result of
small-scale variabilty in the true air temperature, which we would like to average
out, the mean value of AT from SN 184 and 706 was used.
Short wave radiation showed a mean difference of 3 W 1m2 (2%) and a standard
deviation of 5 W 1m2 (11%). The mean difference is acceptable given the estimated
accuracy of 3%. However, from the plots it appears that the large standard deviation
is the result of an error in one (or both) of the sensors which is proportional to the
magnitude of insolation. Calbration data showed that the SW sensor for VA WR
SN 184 had a significant post deployment calibration error (about 4%) which could
have accounted for the observed differences, while SN 706 performance was within
specifications. Thus, we chose to use the SW data from SN 706.
Barometric pressure showed a mean difference and standard deviation both
equal to 0.20 mb. This value is actually slightly less than the estimated accuracy
of 0.26 mb. In addition, pre and post calibrations for both instruments indicated
excellent performance. Since both sensors performed equally well, the choice of the
"best" sensor is arbitrary. We chose to use the BP data from SN 706.
Relative humidity showed a mean difference and standard deviation both equal
to 1 %. This value is less than the estimated accuracy of 3%, and we can conclude
that both instruments within their specifications. However, from the plots it can
be seen that the observed difference is principaly due to a high-humidity bias, with
SN 706 reading approximately 2% higher than SN 184 for RH greater than 90%.
It was found that SN 706 performed better than SN 184 in both pre and post
calibration tests, particularly in the RH range between 80% and 95%. Thus, the
RH measurements from SN 706 were chosen for the final data set.
25
The fial meteorological data set, determined to be the best available observa-
tions from the two VAWRs in the manner described above, is shown in nine sections
in Figure IDa-i. Note that the 14 day section intervals do not divide evenly into the
129 day experimental period. Rather than begin a tenth section, the ls.t three days
are not shown. The original 15 min data have been smoothed over four hours and
plotted every two hours. The variables are the same as those shown in Figure 8,
except here AT (solid) and SST (dashed) have been combined in one paneL.
3.2 Air-Sea Fluxes
The fluxes of momentum, sensible heat, and latent heat for the MLML site
were computed from the meteorological varables shown in Figure 10 using bulk
aerodynamic formulae of Large and Pond (1981; 1982). Several steps were necessar
to go from the raw meteorological variables to the momentum flux and total heat
flux. The most involved of these is the estimation of outgoing longwave radiation
from the sea surface, including a correction for cloud cover.
The outgoing longwave radiation can be estimated by assuming that the earth
is nearly a black-body radiator and accounting for the presence of clouds. A review
- of several such approaches is given by Fung (1984). We used a formulation for LW
as a function of SST, AT, and the mixing ratio from Clark et aI. (1974). Corrections
for slight departures from black-body behavior are included. Also included in this
formulation is a cloud correction function F(n), where n is the cloud fraction,
a number between zero (no clouds) and one (complete cloud cover). We used the
expression F( n) = 1 - b * n2 where b is an empirical parameter which vares
with latitude from about 0.5 at the equator to 0.8 at 800N (see Fug, 1984). The
diffculty is in determining the cloud fraction n.
26
The approach taken was to compute the clear sky shortwave radiation from
astronomical theory (List, 1984) and estimate the cloud cover by comparing the
computed clear sky vaue to the observations. The principal steps in this pro-
cess are outlined below. The shortwave radiation record was corrected for a smal
rught-time bias by subtracting a rught-time mean of 5.49 W 1m2 from all data. A
theoretical estimate of clear sky shortwave radiation for the MLML site was made
using the formulations of List (1984). The theoretical values were "tuned" to be
a good match to the sunruest days of the experiment by picking an albedo of 0.06
and an atmospheric transmission coeffcient of 0.77. The cloud fraction was then
estimated from the ratio of observed to theoretical shortwave radiation and checked
for consistency, i.e., a sensible distribution between zero (sunniest day) and one
(cloudiest day). This techruque, of course, works only during the day. Night-time
vaues of cloud cover were estimated by linear interpolation between the nearest two
daytime values. After interpolation, the cloud fraction record was smoothed over
30 hours to reduce sensitivity to the day Inight transitions.
The observed meteorological variables and the cloud fraction estimate are used
as input to a flux computation routine. Output from the irutial flux computation
includes stabilty, wind stress, sensible and latent heat flux, and cloud corrected
longwave radiation. Along with the observed shortwave radiation this forms a sur-
face flux time series for MLML which is complete except for precipitation. As a
fial step, the heat flux components are combined to form the total heat flux.
The MLML bulk fluxes are presented in Figure lla-i. The fluxes are computed
from the 15 min meteorological variables, but have been smoothed over four hours
prior to plotting. The five panels show (from top to bottom) sensible (solid) and
latent (dashed) heat flux, shortwave (solid) and cloud corrected longwave (dashed)
radiation, total heat flux, wind stress magnitude, and wind direction. The sign of
27
SN model depth pre post data recovery
2535 XL-I00 80 y y good data2539 XL-I00 102 y y good data2538 XL-lOO 118 Y n good data, failed during post-cal2534 XL-I00 134 y n no data, quit before deployment2540 XL-I00 150 y y good data2533 XL-I00 166 y y good data
3263 XX -105 182 y Y good data2536 XL-I00 198 y y good data2541 XL-I00 214 y y good data3299 XX-I05 230 y y good data3291 XX-I05 246 y y good data3301 XX-I05 262 y n no data, water leak
2542 XL-I00 278 y n no data, scrambled EPROM3264 XX -105 294 y n partial record, water leak2537 XL- 100 310 y y good data
Table 4: Tabulation of instrument serial numbers, depth of deployment, and datarecovery for the Brancker Submersible Temperature Loggers. Pre and post indicatepre-deployment and post-deployment calibrations, respectively.
sensible, latent and total heat fluxes as presented here are positive for a heat gain
by the ocean.
3.3 Upper-Ocean Temperature
Complete records of high quality temperature data were obtained from 11 of
the 15 STLs, a partial record was obtained from the 12th instrument, and no data
were recovered from the remaining three (Table 4).
The three failures left gaps in the temperature record at 134 m depth and be-
tween 246 m and 310 m depth. Instrument SN 2538 failed during post calibration
and was later repaired; good data were obtained during the deployment. SN 2534
28
and 2542 sufered from a ribbon cable chafng problem which was determined to
be generic to the Model XL-I00. This problem was corrected for XL-100s deployed
after MLML. SN 3301 and 3264 were found to have small amounts of water (ap-
proximately one tablespoon) in the pressure case upon recovery. SN 3301 lost all
data due to flooding, but a partial record (the first 90 days) was recovered from SN
3264.
The ten STLs which had post deployment calbrations were found to be ex-
tremely stable, i.e., the mean difference in observed temperature using the pre and
post calibration constants was 0.0050 or less, comparable to the instrument accu-
racy. This made the choice of pre or post deployment calibration coeffcients for
these units arbitrary. Due to the lack of post calibration for SN 2538 and 3264, the
pre calibration coeffcients were used for all .instruments.
Temperature data were also obtained from the USC and Lamont MVMSs de-
ployed between 10 m and 90 m. In order to be compatible with our STL sampling
interva the USC raw data, originally sampled at 1 min intervals, were averaged to
15 min. Similarly, the Lamont data, originally sampled at 4 min, were averaged
to 15 min intervals. Calibrations were not available for any of the USC or Lamont
temperature sensors.
The USC records were complete, and no further processing was required. The
Lamont temperature records at 30 m and 90 m had a gap between 27 July and
26 August. This segment was filled using linear interpolation between the nearest
neighbors in the vertical, i.e., 30 m data were filled using USC MVMSs at 10 m
and 50 m, 90 m data were filled using STLs at 80 m and 102 m. The Lamont
70 m temperature record stopped on 30 June. The missing 70 m data were also
filed by interpolation, using the MVMS at 50 m and the STL at 80 m. During the
processing of the Lamont temperature records, we took the opportunity to fill in
29
the missing data from the 294 m STL, interpolating between the STLs at 246 m
and 310 m.
It was clear from the initial CTD cast (Figure 4) that the water column was
fairly well mixed at the start of the deployment. The CTD temperatures were
within about O.I°C from the surface to 300 m, with a mean of about 8.130°C.
The temperatures observed on the mooring were very stable immediately following
deployment, after which significant surface waring began. Thus, we chose to
compare mooring temperatures averaged over the fist 8 hrs of 30 April to the
expected values based on the CTD cast. Instruments with good pre and post
deployment calibrations are shown in Figure 12 as circles, and are in good agreement
with the CTD profile. Instruments without good calibrations are shown as crosses
in the figure, and all but the Lamont 90 m MVMS appear suspect due to poor
agreement with the CTD cast and the appearance of strong temperature inversions
with depth.
As a first attempt at an ad-hoc "adjustment" of the temperature sensors with
suspect calibrations, we forced their initial values to agree with the average of
the STLs. The depth-mean from 80 m to 246 m of the STL 8 hr averages was
8.1304°C. The 8 hr averages for the other 7 sensors, and the adjustments used
to bring their means into agreement with the STLs, are given in Table 5. The
adjustment was applied as an additive constant to all temperatures in the record
for a given instrument.
The processing steps described above resulted in time series of temperature at
17 depths between the surace and 310 m depth (Table 6).
The temperatures are plotted as overlapped time series in Figure 13a-i. The
surface data are shown as a solid line, the 10 m data as a dashed line, etc., with
successive depths alternating as solid and dashed. These data were averaged over
30
source depth 8-hr mean adjustment
VAWR 0 8.1205 +0.0099USC MVMS 10 8.1091 +0.0213Lamont MVMS 30 8.1791 -0.0487USC MVMS 50 8.0964 +0.0340Lamont MVMS 70 8.0568 +0.0736Lamont MVMS 90 8.1409 -0.0105Brancker STL 294 8.0198 +0.1106
Table 5: Temperature adjustments used to bring the seven instruments withun-reliable calbrations into agreement with the STLs between 80 m and 246 m.Mean temperat_ures over the first eight hours of 30 April were used in the compar-isons.
2 hr prior to plotting. Note the occurrence of small, but persistent temperature
inversions between the surface and 10 m depth (e.g. 5-7 May, 28-31 May). These
are presumably not real, but rather a result of imperfect correction of the VAWRi
SST record. Inversions at other depths can occasionally be seen, which may be the
result of the crude nature of the temperature adjustments described above.
The temperature data are shown vs. depth and time as contour plots in Fig-
ure 14a-i. The data were averaged over 18 hr prior to contouring.
lr
3.4 Upper-Ocean Currents¡,
,N~ \
A complete record of currents was obtained from the RDI ADCP. Currents in
earth coordinates (i.e. rotated from a coordinate system relative to the instrument
into a geographical coordinate system using the measured pitch, roll and heading)
were averaged to create time series in 16 m depth cells between 86 m and 310 m
(Table 6). The ADCP recorded one profie (an average of 60 transmissions) every
31
depth temperature currents
0 VAWR 70610 USC MVMS USC MVMS30 Lamont MVMS Lamont MVMS50 USC MVMS USC MVMS70 Lamont MVMS Lamont MVMS80 Brancker STL90 ADCP (86 m)
102 Brancker STL ADCP118 Brancker STL ADCP134 ADCP150 Brancker STL ADCP166 Brancker STL ADCP182 Brancker STL ADCP198 Brancker STL ADCP214 Brancker STL ADCP230 Brancker STL ADCP246 Brancker STL ADCP262 ADCP278 ADCP294 Brancker STL ADCP310 Brancker STL ADCP
Table 6: The sensors used to provide temperature and current data at a given depth
are shown. If no sensor is shown then no data were available at that depth ( except
for the 90 m temperature which was available, but not used due to an unresolvedtiming problem).
32
15 minutes. The earth-coordinate current profiles were computed on a ping-by-ping
basis by the ADCP, so no further processing was necessary. Although the ADCP
passed all pre and post deployment diagnostic tests, no laboratory calbration of the
ADCP currents was possible. Instead, the ADCP currents at 86 m were compared
statistically to the MVMS currents at 50 and 70 m. The comparison showed rms
differences in speed of 2-3 cmjs, and in direction of about 70. Since these differ-
ences were near the expected instrumental error level and comparable to differences
between the 50 m and 70 m MVMS records, it was concluded that the ADCP was
performing properly. Coherence between the ADCP and MVMSs was significant
out to a frequency of about 0.3 cph where the ADCP spectra reached a noise floor.
Currents were also obtained from the USC and Lamont MVMSs at 10, 30, 50,
and 70 m (Table 6). As with the temperature data, the 1 min USC samples and 4
min Lamont samples were averaged to 15 min to be compatible with our nominal
sampling interval. The current records from the two USC instruments and the
70 m Lamont instrument were complete, and no further processing was done. The
Lamont record from 30 m stopped on 9 July due to a broken rotor. The missing
data were filled using linear interpolation between the 10 m and 50 m USC MVMSs.
The Lamont MVMS at 90 m recorded good data only for the first three days of
the deployment due to a compass problem, and was eliminated from any further
processing. Instead, the ADCP currents from the 86 m depth bin were used.
Figures 15a-i and 16a-i show the east and north velocity components from 11
depths as overplotted lines. Time series from the MVMSs at 10, 30, 50, and 70 m
are shown along with ADCP data from bins at 86, 102, 118, 150, 182, 214, and
246 m. Data were smoothed over 8 hr prior to plotting. In order to distinguish
data from different depths, a variety of line types is used. The 10 m data is plotted
as a solid line and data from 30, 50, and 70 m use progressively longer dashes, At
102 m and below all lines are solid. The currents below 100 m have little varation
33
with depth and form a "clump" of solid lines. When there is substantial shear in the
upper 100 m the solid 10 m line and the dashed lines at 30, 50 and 70 m separate
from the clump of solid lines from 102 m and below.
Figure 17a-i shows currents at selected depths between 10 m and 250 m as
vector stick plots. The nine panels, from top to bottom, show data from 10, 30,
50, 70, 86, 118, 150, 198, and 246 meters. A stick pointing upwards represents a
current towards the north. These data were averaged over 8 hr prior to plotting.
34
.. 100~..:i0:
..E 1 020..a.CD
980r: 1 000
E"-3: 500..3:V) 0
20..U0.. 1 2l-~
420..u
0
.. 1 2l-V)V)
4180..
0..0 0
3:
-180..(I 20"-E.. 1 0V)3:
60
Figue SaMeteorological variables from the two VAWR.
35
.- 100~'-:ia:
.-Ê 1 020'-0-m
980.- 1 000NE"~ 500'-~(/ 0
20.-Uo'- 12i-~
.-Uo
'- 12i-(/(/
.-o'-o~
-180.-,20E'- 10(/~
60
420
4180
-. --, '--'
o
o
Figure 8b
Meteorological variables from the tw VAWR.
36
_ 100~..:cCt
-Ê 1 020..a.m
980- 1000NE"'~ 500..~en 0
20-Uo.. 12l-~
-Uo.. 12l-enen
-o..ci~
-180-,20E.. 10en
~ 0
60
420
4180
o
Figue 8eMeteoro1ogieal variab1es from the tw VAWR.
37
.. 100~..:ie:
..E 1 020..0-m
980.. 1000NE
~ 500..~en 0
20..U0.. 12i-~
420..u
0.. 12i-enen
4180..
0..0 0
~-180..U) 20"'E.. 10en~
0
60
Figue 8dMeteorological variables from the tw VAWR.
38
4..~~ 0:ia:
-4
.. 1..E 0~a.CD -1
..N 30E..~ 0~~ -30(f
..U0~ 0..~
-1.. 2u0~
0..(f(f -2.. 5(I..E 0~w~ -5
.. 5(I..E 0~Z~
Figue 9aDifferences between meteorological variables.
39
4-~-. 0:ia:
-4
- 1..E 0-.0-m -1-
C' 30E"'~ 0'-~ -30Vl
-U0-. 0~.:
-1- 2Ua-.
0~VlVl -2- 5en"'E 0-.
W~ -5- 5en"'E 0-.Z~ -5
Figue 9bDifferences between meteorological variables.
40
4,.~.. 0:ia:
-4
,. 1..E 0..
CLCD -1
,. .N 30E'"~ 0..~ -30V)
,.U0.. 0I-~
-1,. 2u0.. 0l-V)V) -2,. 5
U)'"E 0..w~ -5
,. 5U)'"E 0..Z~ -5
Figue 9cDifferences between meteorological variables.
41
4-~'- 0ia:
-4
-..E 0'-0-CD -1-
N 30E..~ 0'-~ -30Ul
-U0'- 0i--i
-1- 2u0'-
0i-UlUl -2- 5en..E 0'-w~ -5- 5en..E 0'-Z~ -5
5 10 15
AUG20
Figure 9dDifferences between meteorological variables.
42
".~-:ic:
"...E 1 020-a-m
1000".N
E..;: 500-;:en
0".U~ 14t-en 10(f..t- 6~
180
".o-o;:
-180
'; 20..E-10
en;:
100
60
980
o
o137Figue lOa MAY
Best available meteorological variables.
43
,.~'-:ie:
,..0E 1 020'-c.m
1000,.NE"'3= 500'-3=(I
,.U~ 14l-(I 10(I"'l- 6c:
180
,.o'-o3=
-180
"' 2 0"'E'- 10(I3=
100
60
980
o
o
o20 21
Figure lOb MAYBest availble meteorological variables.
44
'"~..:cc:
'"..E 1 020..0-m
1000'"NE"3= 500..3=en
'"u014l-en 10en"l- 6oc
180
'"o..c:3=
-180
-- 20"E.. 10en3=
100
60
980
o
o
o 5 6Figue lOc J U NBest availab1e meteoro1ogica1 variab1es.
45
..~'-:i0:
....E 1 020'-0-m
1000..N
E..:: 500'-::(/
0..U~ 14~(/ 10(/..~ 6oc
180
..o'-Cl::
-180
-- 20..E'- 1 0(/::
100
60
980
o
o17 18
Figue 10d J U NBest available meteorological variables.
46
,.~'-:ia:
,..0E 1 020'-0-m
1000,.NE"-
5003:'-3:en
0,.U~ 14l-en 10en"-l- 6~
180
,.0'-c 03:
-180
-- 20"-E'- 10en3:
0
100
60
980
Figue lOeBest available meteorological variables.
47
..~~:i0:
...0E 1 020~a.m
1000..N
E..:= 500~:=V)
..U~ 14l-V) 10V)..I- 6~
180
..o~o:=
-180
"' 2 0..E~ 10V):=
100
60
980
o
o
o
Figure 10£Best available meteorological variables.
48
..~'-:i0:
...cE 1 020'-
0-m
980
1000..NE..~'-~en
..U~ 14 _l-en 10en..l- 6ct
180
..o'-o~
-180
l; 20..E'- 1 0en~
100
60
r
500
o
o
o5
Figure 109Best available meteorological variables.
49
..~"':i0:
..JJE 1020"'a.CD
1000..N
E..~ 500"'~en
..U~ 14l-en 10en..l- 6~
180
..o"'Cl~
-180
~ 20..E"' 1 0en~
06
100
60
980
o
o
Figue lOhBest available meteorological variables.
50
-~..:ie:
-.0E 1 020..
0-m
980
1000-NE"'~..~(f-
U~ 14~(f 10(f"'~ 6oc
180-o..o~
-180
"; 2 0"'E.. 10(f~
100
60
500
,
~,""~
L
l\
o
o
o 25 26Figue lOi AUGBest available meteorological variables.
2
51
..N
E 0'".. "
~~ -40..0.. -80rncCDrn -120..N
600E..400~~
~ 200.. 0~
rn-200..
N 600E.. 400~~.. 2000CD 0.t.. -200CDc
0.8..NE 0.6..z~ 0.4
rnrnCD 0.2~..rn
0.0
..0~ 90~"' 0rnrnCD -90~..rn
,,,
"1
1, 1, ,..1
\,
-- - - - - -- --- ---- -~ ---- --- ------------ ------
30
Figure llaAir-sea fluxes
7
MAYfrom bulk forme.
13
52
-NE 0"' '\ ,~ " \ \'- -40 "J \ .,\ I'-C "',,', ,
I"' -80rnc:CDrn -120-
NE 600"'
400~'-~ 200"' 0~ -----
rn-200-
N 600E"' 400~'-- 200cCD 0-r- -200CD
c:0.8-
NE 0.6"'z'- 0.4
enenCD 0.2L.-en
0.0-0'- 90L.
"" 0enenCD -90L.-en
14
Figue llbAir-sea fluxs
53
,,,.,,,..,,I, I
'./
27
-('E 0"3: -40'--c" -80(Ic
CD(I -120-N
600E"4003:'-
~ 200" 0~(I
-200-N 600
E" 4003:'-- 200cCD 0..- -200CDc
0.8-NE 0.6"z'- 0.4(I(ICD 0.2L.-(I
0.0-0'- 90L.
'"0
(I(ICD -90L.-(I
-,\
'\ -I ,,~ , \ ,.. ~I ¥ \"",_1
.. 1"
\1\..\ I\, I\ I'-
Figue HeAir-sea fluxes from bulk forme.
54
..NE 0"?;'- -40-c" -80
UJcQ)UJ -120
..NE 600? 400'-~"~UJ
200
o
-200..N
E"?;'--cQ)..Q; -200c..N
E 0.6"z'- 0.4UJUJQ) 0.2~-UJ
..0'- 90~"'
0UJUJQ) -90~-UJ
600
400
200
o
0.8
0.0
Figue lldAir-sea fluxes from bulk forme.
55
-N
E 600..4003='-
~ 200.. 0~ ------ ----------- -----
UJ
-200-N 600
E.. 4003='-- 2000CD 0.L- -200CD
c:
-NE 0..3='- -40-o.. -80
UJc:CDUJ -120
-NE 0.6..z'- 0.4
UJUJ
~ 0.2-UJ
-0'- 90L.
"'0
UJUJCD -90L.-UJ
"'.. -,'\A.,'" \ , \.... ,,' \ ..,.. , ' ..
..
0.8
0.0
8
Figue HeAir-sea fluxes from bulk forme.
56
-NE 0"~ ,.. -40 ,
, ,- ,c ' ,~" -80(Ic
Q)(I -120-N
E 600"400~..
~ 200" 0~(I
-200-N 600
E" 400~..- 200cQ) 0..- -200Q)c
0.8-NE 0.6"z.. 0.4(I(IQ) 0.2~-(I
0.0-0.. 90~-c 0(I(IQ) -90~-(I
~.I-,.., \ -,, ---, \I \, ,--I , I, I "'.','
9 10Figue 11fAir-sea fluxes
14 15 16
JULfrom bulk forme.
17 18 19 20 21
57
..NE 0..3='- -40-c.. -80(Ic:Q)(I -120..NE 600~ 400'-~..~(I
-200..N
E..3='--cQ).lq; -200c:
..NE 0.6..z'- 0.4(I(I~ 0.2-(I
..0'- 90L..-""
0en(IQ) -90L.-(I
'ii ,- i ,-\\, ',",,-',
200
o _-------------______-_ -------- - -- ------ -- - - -----
600
400
200
o
0.8
0.0
Figue l1gAir-sea fluxes from bulk forme.
58
200
o
"N
E 0" 1
3=1,'- -40 ,- " ' ,
0 I"''' \.., ," -80 \,
rncQ)rn -120"
NE 600~ 400'-~"~rn
-200"N 600
E" 4003='-- 2000Q) 0..- -200Q)c"NE 0.6"z'- 0.4
rnrn~ 0.2-rn
"0'- 90L.
"' 0(I(IQ) -90L.-(I
-- - ------------- - -- - -- -- ----- ------------ - - ------ - ---
0.8
0.0
;'
Iit(\
6 19
Figue llhAir-sea fluxes from bulk forme.
59
..N ,-
E 0"' ,
"
3: '\ ' ,I.. -40 i \ .. I ,I" \
I' I,. i
,..' \ i " \ ,"'1 \"- \ ,,.I I0 , i i, \ ..I I ,"' -80 i i i
UJ , 1'1C , iQ)
I iUJ -120 ,
..N
600E"'4003:..
~ 200"' a~ ---------- - - - --- - --- ------ ----
UJ
-200..N 600
E"' 4003:..- 2000Q) a..- -200Q)c
0.8..N
E 0.6"'z.. 0.4
UJUJQ) 0.2L.-UJ
0.0
..0.. 90L.
-0 0UJUJQ) -90L.-UJ
20 2
Figue HiAir-sea fluxes from bulk forme.
60
0 xx
x
-50 x
x0
x-100 0
x-E--= -150 0a.Q) 0
"C0
-200 00
0
-250 0
-300
8
x
8.02 8.04 8.06 8.08 8.1 8.12 8.14 8.16 8.18 8.2temperature (deg C)
Figure 12Eight-bour mean temperatures versus depth.
61
~~
-.l)o
temperature (degrees DC)l)No
l)eno
c.o
-------'------.._----
N
c.
.t
01
en
-.
l)
(0
..o
....
N
..c.
Figue 13aSub-surface temperature tim series.
62
(X
~to
~s: a
~ ~~
~~
~v.
~.t
~U1
~en
~'-
'-(Xa
~.t
~U1
~en
~'-
temperature(X~a
(degrees °C)(Xena
toaa
--~--.. ---
Figure 13b
Sub-surface temperature tim series.
63
-- -:----c:..c_;===_
-:
temperature (degrees DC)
..(J
()(J
I'()
I'to
v.o
v.-"
to(J
-"o(J
to
Figure 13cSub-surface temperature tim series.
64
L "CZ ..
()
..CD
N0
N..
NN
NU
N~
"0
....
..N
..U
..~
(J
..m
temperature (degrees DC)
CD
o.... ..
Uoo
Figure 13d
Sub-surface temperature tim series.
65
temperature (degrees DC)-"
-.0
I\ui
I\0)
I\c. -.CZ I\
(X
I\to
v.0
-"
too o
I\
v.
-"v.o
'--..----'--:=.:
"---...._-
~c.Cr
ui------'..-
.:i
0) ,,,\i
"..-.
(X
Figure BeSub-surface temperature tim series.
66
~0
~~
~'"
~u.
~..
~c. (J
Cr ~en
~-.
~()
temperature (degrees DC)
-.o
(0o
(0i_----
.,--~ .... -
_oJ..~I---_..
-..~..------,.
..,..--,"--..
(_J'-- ..
-'---~--..
",-'
':..,
oJ---"..
(0
'"o
'"~
--..,..--,.-J~--,--....
c_,......
-!.'"'"
~o
Figure 13fSufi-surface temperature tim series.
67
~u.o
temperature (degrees °C).. ..
m a ~a a a
I'c.
I'~
I'(J
I'm
LC I'..r
I'co
I'to
c.a ----",-
..)'-c. -..--.. ,
.. ~, ..
-' -"'
'I.. "r
~
iL-
¡,I' "fi
): --C c. ---
::.G' .. -
"..,.... ,~
1,..-----,
(J
Figure 13gSub-surface temperature tim series.
68
..a
....
..~ N
CGì ..t.
....
temperature (degrees °C).. ....a (0
a a t.a
en
..
co
(0
oi
..en
..
..co
..(0
Figue 13h
Sub-surface temperature tim series.
69
..oia
..0
'"0
'"~
'"'"
'"c.
'"~
'"); 01
CG) '"
en
'"..
'"(X
'"to
c.0
c.~
temperature (degrees DC)
too
~~ c.o~
o
'"
Figure 13iSub-surface temperature tim series.
70
,.E..:5 1 60a.Q)-0
240
o
80
o
30 1 2 3 5 6 7 8MAY
4 9 10 11 12 13
Figure 14aContours of sub-surface temperature.
71
- ..
E..:S 1 600-Q)"'
240
o
80
a:.~o
14 15 16 17 18 19 20 21 22 23 24 25 26 27MAY
Figure 14bContours of sub-surface temperature.
72
--E'-:5 1 60a.Q)
"U
240
o
80
~.?o
28 29 30 31 3 5 6JUN
7 8 9 101 2 4
Figure 14c
Contours of sub-surface temperature.
73
..E--:5 1 600.Q)"'
o
80
240
11 12 13 14 15 16 17 18 19 20 21 22 23 24JUN
Figure 14d
Contours of sub-surface temperature.
74
..E'-:5 1 60a.Q)-0
240
o
11.511.010.5
10.0
9.5
80
II
øi'0 ~ .
25 26 27 28 29 30 1JUN
2
Figure 14e
Contours of sub-surface temperature.
75
3 4 5JUL
6 7 8
..E~:5 1 60a.m""
a
809.0
240 CD
b~
9 10 11 12 13 14
Figure 14fContours of sub-surface temperature.
15 16
JUL17 18 19 20 21 22
76
..E'-:: 1 60a.(l
"U
o "-u¡~,O\O.O~"-
9.5__ ""
'-~ ~!~~
~ ~ = :::2~ -- .~9.s
80
aiUi
Cß'0
240
23 24 25 26 27 28 29 30 31JUL
2 3 4 5AUG
Figure 14gContours of sub-surface temperature.
77
,.E..:S 1 60a.ID"'
o
ii:r 9.5
~ i~-=U
~.9'OS
80
240
6 7 8 9 10 11 12 13 14 15 16 17 18 19AUG
Figure 14h
Contours of sub-surface temperature.
78
.-E..:5 1 60a.Q)"'
240
o
11.°,0.510.0
9.5
80
20 21 22 23 24 25 26 27 28 29 30 31 2AUG
Figure 14i
Contours of sub-surface temperature.
79
~~ ~
velocity east (em/see)I~a a ~a
(.a
..
I\
(.
~
(J
en
co
to
..a
..
I\
..(.
Figure 15aVelocity tim series, East component.
80
'-
-"co
-"(0
I\š:
0
~ I\-"
I\I\
I\VI
I\~
I\U1
I\m
I\'-
I
m9
velocity easti~o
(cm/sec)iI\o
-"~
-"U1
-"m
"c" ;;- -1....
_,"~~;_~;:_l;==:::~
..:;-
--- -:-=----=--~;;;::,.
Figue 15h
Velocity tim series, East component.
81
9
--~--~""-
.... _::~
- ::::::: -:---..-"
_ J
-....
..
'-cz
~(X
~(0
v.o
v...
~
v.
~
U1
en
..
OJ
(0
..o
I~9
velocity east (cm/ sec)i~o
"",.. \--.. -- - -~- --..
Figure 15c
Velocity tim series, East component.
82
o
..-
~
velocity east (em/see)I
No o N!=
~~.~-~................
'.:i
Vo
~N
~
~U1
~0'
~'- -.CZ ~
CD
~to
N0".
:;¡¡o'"
Nl\~
NN
NVo
N..
Figue 15dVelocity tim series, East component.
83
I.ta
velocity east (cmj sec)i
'"a !=
'"
'"01
'"0)
'"'- ..CZ '"
co
'"to
v.a
v.
.t'-Cr
01
0)
..
co
Figue 15eVelocity tim series, East component.
84
v.
--~
--c. ui
Cr --en
---.
velocity east (cmjsec)I~
!= o
to
--o
----
--'"
cx
--to
'"o
'"--
'"'"
Figue 15fVelocity tim series, East component.
85
~!=
velocity east (cm/ sec)I
Na pNP
-'
Nv.
N~
N(J
Nen
c.C N'-r
N(X
'"-------'
N(0
v.a
v.-'
N
~C v.G)
~
(J
Figure 15gVelocity tim series, East component.
86
a
~~
~J: '"
CC) ~
v.
~~
~()
en
-.
co
to
en
~-.
~co
~to
velocity east (cm/ sec)I
'"a ~a a ~
....-...,---------...........-_....
- ~::::-""'ii-S::::a
---
:::::-;':~-
- -----
- -
Figure ISh
Velocity tim series, East component.
87
I'I'
I'(.
I'~
I'): ()cG) I'
m
I'..
I'(X
I'to
(.a
(.-.
I
ma
velocity east (em/see)i I~ I'a a a
I'a
I'
-:....
.~.........~....-.c--.._,
:-:S-;~;-~~-~~-~
-.
,.':.---~....._-----....-
--------'
.~~~~::::::..
..- ~ ---:-:-
...,
I'
Figure lSiVelocity tim series, East component.
88
š:~
velocity north (cm/sec)a .ta
c.a
~.f-
r
..
N
c.
.t
ui
en
..
CX
to
..a
....
N
..c.
Figure 16aVelocity tim series, North component.
89
velocity north (em/see)I~~ o ~
~
--~
--01
--Ol
..
CX
-"l.
i-s: 0
~ i--"
i-i-- ;"-4
i- ~v..-.
t - -- -i-~
i-01
i-Ol
i-..
Figure 16bVelocity tim series, North component.
90
velocity north (cm/sec)i I I I
(J .. VI '" --0 0 0 0 0
'"(X
'"co
VI0,. -40 __
VI--
..
................_.. .
-- ..-..
--
'"
VI
(J'-CZ
m
'-
(X
co
--o
Figure 16cVe10city tim series, North component.
91
0'
..r- ..CZ ..
OJ
..to
I'a
I'..
I'I'
I'ú.
I'~
I
I'a
velocity north (em/see)i..a a a..
....-------------------------- -----------------.
.-
.-...-._-.;--~---
..I'
ú.
..~
..(J
.;~
Figure 16dVelocity tim series, North component.
92
velocity north (cmjsec)~ ~ '"~ 0 0 0
'"01
'" - ---ai .. -
'"Co -.CZ '"
(X
'"to
~..-:..:::..:-..... - .
VI "' ------_................0 ...--....
CoCr
(X
'"
VI
~
01
ai
-. --,/ '\- -
Figure 16eVelocity tim series, North component .
93
~
~c. (J
Cr ~en
~..
~OJ
~to
'"0
'"~
'"'"
to
~o
~~
~'"
~VI
I
'"o
velocity north (em/see)io != o~
-.::::_
:.c:- - .....~.---------..
....'"'" ...- ......~--
-- :. :: :: :. -_ .-A_ __ __- -
Figue 16£Velocity tim series, North component.
94
velocity north (em/see).. ..a a aa a a
.' -::- .. ~"" - - --- -- --VI .._~": --
..-"':".,"" ---'
""~
""C1
""en
CoC ""~r
""(X
.-:::_-----......""(0
VI0
VI ---.._--....
..
..--"" ----..
~C VI
G)
--~.,-
C1
Figure 16gVelocity tim series, North component.
95
..a
....
..~ I\CG) ..
VI
..~
en
'"
co
to
(J
..en
'"
co
..to
velocity north (cm/sec)II\a I\a ~ap
Figure 16h
Ve10city tim series, North component.
96
I.t0
~0
~~
~~
~c.
~.t
~); ui
CGJ ~
en
~..
~(X
~to
c.0
c...
velocity north (cm/sec)
.to 0
..
~
Figure 16iVelocity tim series, North component.
97
40E _o 0--
-40. _ __ ~ ~II//Irt\\\\~\\~.~~"'-
40E _o 0", -40
- - --...rØIU~\\~~_~~-
40E .-o 0to _ 40
~¿¡////lllmI_~. .
40E --o 0" -40
~1.m\\\\I\I\i\~\\\~~
E 40 ..CD 0IX -40
-"~l1$/Æ\\\_~~
E 40 --IX 0 ---
.
.
-"~~ß~\\\\\\~~-- -40
E 40 --o 0 -It-- -40
~l\\\\\\~.. .
E 40IX 0 --m-- '-40
-~!A\\\ll~~.
E 40CD 0 --~N -40
.
.
- - -~J~\\\\\i-~30 1 2 3 4 5 .6 7 8 9 10
MAY
11 12 13
Figure 17aSub-surface velocity vectors at selected depths.
98
40Eo 0" ~\\\,-,..- -.. "'~~¡p/lrrr~rrrFlIØlf_-40
40~ 0 '1 ~\\ir'I" _ 40
- J- ~rø~rrrrr~~~p~R/.-.
oin
40E
o-40
~~I - _lJJ~~~rr-r~r~~~~~E 40o O~~\~~~~" -40 - '-~~~rrrrrl'p;jH~
40~ 0 -., -- -IX -40
--i~~rrrr-~~~~~~E 40IX O~~~ i-.... -40 ---~~~~r~/'r-~~~~~
~~ - - ---A:.__~~~~~~~~
~ -~l~_!~i~pm_E 40to O~ ~"" -~N -40 ~ - '-'_ U%~~J~~_ß~~L~~~l~
14 15 16 17 18 19 20 21 22 23 24 25 26 27MAY
Figure 17bSub-surface velocity vectors at selected depths.
99
40E
~ _ 4 0 -l-l/IIIII/IIIIIi'I/ II/U//11/V/IIIW111IV////IlII////IIII/IIII/I//IIIW/llfl6#lIlr
E
g _ 4 0 -lf/f/f//I/I1/11 WIIIIIII//lI/IIIII//III/II/IIIII///III/I/lllft/II/lII//IIIII////li/11////II/1/
Eg 0 -l/f/ff!l///III///////II/////I/////II/III//III/I/I///I//I////////11I1I1I1//////U/I/l!f6ll/fP
-4
40E
g _ ~4 .$///fIIl/IIIPIIII/IIIIII/IIIIIIIIII/IIIII/lIIII/I 1 i /1~i1111/1111~i1/1~i1111~i 111/1/111111/////!II///IFA40 ..40
E
:g _ 4 0 -l-lIIII/IIIII/I/IIUlIIIII/I/IIII///IIII///I/I/lIII//II///I/////////lIii/U/iilI~pr
E 40
~ _ 4 0 -l-lIIIIIII/II///IIV/I/III//III1I///I/I/1II/I/JII///////////////II///////I/~
E 40
~ _ 4 0 -lfI/II//ll/lllllllffIIIIIH//I/III///II/I///III///////////////////////lII/////II/~~
E 40
~ -4 0 -lIIIIIUI//lffllllllll/ll/lllffll/III////////////III/////////IPlP
E 40
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28 29 30 31 1 2 3 4 5 6 7JUN
8 9 10
Figure 17cSub-surface ve10city vectors at se1ected depths.
100
20E
~ _ 20 ~/rrl\'f/\\~I\\"/I\\\liiilllllllll\\\\\\\\\~~\\U/'I\\\\\I\\\V/I?-F1~
20E
g _ 2l ~'''''''/ll/\~\''\~/I\\'''II'''''-'!~ ~n~~~'VII//I"iill\IiiUlr/l.~
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~/\\V,\\~\~\\\\\\\\\'W",'r"\II'~,-i~!t ¡~\\\VJII/JI'III/Ilf~R"n
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Figure i 7 dSub-surface velocity vectors at selected depths.
101
~-:~-:i'~~~~~~~s~- :- ~~-~= ¡
, ~ -:~t.~: ~ : - ~ - - : ~~- :-:- : -: - : -~ ~ ¡
~-:~t.-: : :--: : :~u: -~~..~~~ -~~-:~~: :- :-: : -~~~: :- .~/~~
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~ _:~+~~: ~.: -: :~~ ~ ~ ~\~ =~i. ¡
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. ~ -:~t - : - : _.~ : ~:~ :-: : -~ ~: ..-: ¡25 26 27 28 29 30 1 2 3 4 5 6 7 8JUN JULFigue 17eSub-surface velocity vectors at selected depths.
102
20Eo.. ¥ Y~~::rl'fI'\\I\\\\\\\\~\~~'''~A'P~~
E ~,."'il/iiiiiiil\iill\\~_- - Jl~"l/.K~
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.,11,. .'\1/11 11111/1 ,,~.._ ~\\Wp'ø.
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~ : : .~ .~/_'''~--~ ~\\\~~ :- ¡
= : : ~ ~~p,,~~~ ~ii\~~: - : -I
~ -~ ~ : ~- ~ _.~''':~~-: ~I/~: :- ¡
i -~ ~ : -: ~ --~':\~--: ~/~~;: :-19 1 0 11 12 1 3 1 4 15 1 6 1 7 18 19 20. 21 22
JUL
~-:H~ 2~.. -20
~ ~~.. -20
~:;r
g
r
Figure 17f
Sub-surface velocity vectors at selected depths.
103
Eo 'j/'r'y'rrr'Y'""\'~-"\\\"""flr ,;- .... -- ..
E :i,;- ~4/,.;rI\\\I"~,..--/lIIII1.."IIIIJ/r .. - _ -..../..
EoIt -20 ~., 4/11\\~../~"."1111~ - -, ,,-,I/'
~ -~~: .: ~ : : -~~y~ ~:"~.,"~/~: : :.1
~ ~!t~: ~~~ ~ -~ ~ ~~III\~~~'-;://r ~ :- :-1E
IX ~"" ~ --ø/I\\~~gt\.w#, - ~
E
~:; -..n/I\\\~~../,ø..~, -
E
~ i7 _///III\\\\\\\~"'.-I/IIÅl~~_
E 20~-_~//I/1I1I\\\\\,..I"I/IT~ __
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23 24 25 26 27 28 29 30 31 1 2 3 4 5
JUL AUGFigure 17 g
Sub-surface velocity vectors at selected depths.
104
Eo
-4040
o
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o
-4040
o
o..
Eo,.
Eo10
Eof'
-4040
to 0co
-40
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-40
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-40
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-40
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40 ._",_,,.,I~\\I~~~I£\lk\\\\\\\III\\\\\\\~
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.
.
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:.
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AUG14 15 16 17 18 198 10 11
Figue 17hSub-surface velocity vectors at selected depths.
105
.,
E 40 \ I~\~\~\&\\~~~\\"'\i~~ _ -'-r'l'/T"rJ(l"IlYI¡¡o 0 ~ '.. - 40
E 40 \i~\~\~\~~~~~\~~~~o 0 .If -40
.
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40E 0oto _ 40
.
~~\\_\\..~~~~,,~~- -N~ ~,pP$~~.
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20 21 22 23 24 25 26 27 28 29 30 31 1AUG
2
Figure i 7i d hSub-surface velocity vectors at selected ept s.
106
Acknow ledgments
The cooperation of M. Grosenbaugh in the 1991 mooring design study con-
tributed to its success. The mooring was expertly fabricated at the WHOI rigging
shop under the direction of D. Simoneau. Experimental logistics and cruise prepa-
ration were overseen by R. Trask. The deployment and recovery operations would
not have been possible without the cooperation and assistance of the Captain and
crew of the R/V ENDEAVOR. Much of the substantial effort resulting from pre and
post deployment calibrations of the UOPG instrumentation was borne by R. Payne
and W. Horn. C. Grant and L. Costello of WHOI assisted in the deployment and
recovery operations. N. Brink handled the initial processing of the VAWR data
tapes. M. Samelson handled the initial processing of the Brancker STLs and as-
sisted in the flux calculations. M. A. Lucas assisted with the preparation of the
manuscript. This work was funded by Codes 1122SS and 1123B of the Offce of
Naval Research under Grant Number NOO0l4-89-J-1683.
107
References
Briscoe, M. G. and R. A. Weller, 1984. Preliminary results from the Long-TermUpper-Ocean Study (LOTUS). Dynamics of Atmospheres and Oceans, 8, 243-265.
Clarke, N. E., L. Eber, R. M. Laurs, J. A. Renner, and J. F. T. Saur, 1974.
Heat exchange between ocean and atmosphere in the eastern North Pacificfor 1961-71. NOAA Technical Repòrt, NMFS SSRF-682, U.S. Department ofCommerce, Washington, D.C.
Dickey, T. D., J. Marra, C. Langdon, and D. A. Siegel, 1988. Preliminary resultsobtained from the multi-variable moored system during the Biowatt experi-ment in the Sargasso Sea. Eos, 68, 1703-1704.
Dickey, T. D., J. Marra, T. Granata, C. Langdon, M. Hamilton, J. Wiggert, D.Siegel, and A. Bratkovich, 1991. Concurrent high resolution bio-optical andphysical time series observations in the Sargasso Sea during the Spring of1987. Journal of Geophysical Research, 96(C5), 8643-8663.
Dickey, T. D., D. V. Manov, D. A. Siegel and R. A. Weller, 1993. Determinationof net longwave heat flux at the air-sea interface using measurements fromship and buoy platfo.rms. Journal.of Atmospheric and Oceanic Technology,
submitted.
Ducklow, H. W., 1989. Joint global ocean flux study: The 1989 North Atlanticbloom experiment. Oceanography Magazine, 2(1), 4-7.
Fung, i. Y., D. E. Harrison, and A. A. Lacis, 1984. On the variability of the netlongwave radiation at the ocean surface. Reviews of Geophysics and Space
Physics, 22, 177-193.
Isemer, H. J., and L. Hasse, 1987a. The Bunker climate atlas of the North AtlanticOcean. Volume 1: Observations. Springer-Verlag, Berlin, 218 pp.
Isemer, H. J., and L. Hasse, 1987b. The Bunker climate atlas of the North AtlanticOcean. Volume 2: Air-Sea Interactions. Springer-Verlag, Berlin, 252 pp.
Kraus, E. B., 1977. Modellng and prediction of the upper layers of the ocean.Pergamon Press, Oxford, England, 325 pp.
Lambert, R. B. and G. T. Hebenstreit, 1985. Upper ocean stratification andvariability in the North Atlantic. Technical Report SIAC-84jl778, ScienceApplications International Corporation, McLean, Virginia, 67 pp.
108
Large, W. G. and S. Pond, 1981. Open ocean momentum flux measurements inmoderate to strong winds. Journal of Physical Oceanography, 11, 324-336.
Large, W. G. and S. Pond, 1982. Sensible and latent heat flux measurements overthe ocean. Journal of Physical Oceanography, 12, 464-482.
Levitus, S., 1982. Climatological Atlas of the World Ocean. NOAA ProfessionalPaper No. 13, National Oceanic and Atmospheric Administration, Rockvile,Maryland, 173 + xv pp.
List, R. J., 1984. Smithsonian Meteorological Tables, Smithsonian Institution
Press, Washington, DC, 572 pp.
Paulson, C. A., and J. J. Simpson, 1977. Irradiance measurements in the upperocean. Journal of Physical Oceanography, 7, 952-956.
Price, J. F., R. A. Weller and R. Pinkel, 1986. Diurnal cycling: Observations
and models of the upper ocean response to diurnal heating, cooling, and windmixing. Journal of Geophysical Research, 91(C7), 8411-8427.
Robinson, M. K., R. A. Bauer and E. H. Schroeder, 1979. Atlas of North Atlantic-Indian Ocean monthly mean temperatures and mean salinities of the surfacelayer. U.S. Naval Oceanographic Offce Reference Publication 18, Departmentof the Navy, Washington, D.C., 234 pp.
Siegel, D. A., and T. D. Dickey, 1987. Observations of the vertical structure of thediffuse attenuation coeffcient spectrum. Deep-Sea Research, 34(4), 547-563.
Weller, R. A., D. L. Rudnick, R. E. Payne, J. P. Dean, N. J. Pennington, andR. P. Trask, 1990. Measuring near~surface meteorology over the ocean from
an array of surface moorings in the subtropical convergence zone. Journal ofAtmospheric and Oceanic Technology, 7(1), 85-103.
109
Appendix 1: Cruise Participants
WHOI Participants on Deployment Cruise:
George TupperWil Ostrom
Bryan WayPaul BouchardCarleton Grant
WHOI Participants on Recovery Cruise:
Mark Grosenbaugh
George TupperLarry Costello
Wil Ostrom
Carleton Grant
110
Appendix 2: Chronological Log
The UOPG scientific party arrived at the agent's in Reykjavik at 0900Z, 22
ApriL. The shipping agent for the cruise was the Iceland Steamship Company (Eim-
skip), who provided very good support in general, although we did have to wait 1/2
day for our container to be delivered to our working area. The working area itself
was excellent, a portion of a large warehouse, about 30 feet from where the ship
was tied up. Workbenches were 4 x 8 sheets of plywood set on stacks of pallets.
Power was supplied by a long extension cord and was 220 volts, 50 cycles. We had
brought a step-down transformer and all equipment seemed to work fine on 110V
50 cycles. By the end of the day our container was unloaded and the electronics
test stations were set up and running.
A magnetic survey was done by George Tupper outside the warehouse in an
attempt to find a good location for buoy spins. Unfortunately, the magnetic vari-
abilty was very strong. The magnetic heading to a visual reference point varied by
25 degrees over a distance of 30 feet. It was assumed that this variation was caused
by the pilings under the dock. Since the overhead door opening was high enough to
get a fully instrumented discus buoy through, We decided to do the spins indoors,
sighting through the open door on a small lighthouse which appeared to be 1-2
miles away and had a bearing of 035 degrees magnetic. The magnetic variabilty
indoors was significantly better than on the dock, with a typical variation of 2-3
degrees over a distance of 10 feet The resulting compass variation (Figure 18) didn't
come out quite as well as we would have liked, but we decided not to attempt any
corrective action since the local conditions were less than ideal and the spins done
at Woods Hole with the same instruments and the same buoy were good.
During pre-cruise checkout, Bryan Way found a high current drain in VAWR
SN 706. He found a bad FSK Modem Controller, replaced it, and both VAWRs
111
were up and running. While the spins were in progress, Bryan noticed that VA WR
SN 184 was outputting data through the Argos package every 3-5 seconds (should
be once every 15 ininutes). After the spins were completed, he found a bad O.C.
controller in the Argos package. He replaced that and fixed the problem.
There were a few problems with the documentation of the buoy tension package
and George spent some time making sure things were right before installing it into
the buoy. The final check was to hook the tensiometer to an upright roof support
and pull on it with a forklift to see that tension really was working.
At 1500Z on 26 April, the buoy was moved outside, where the air temperature
was about 4°C, and the wind was estimated at 15-20 knots from the east. At 1624Z,
the two sea temp thermistors were put into an ice bucket and left there overnight.
The buoy was on the ship from midday 27 April til midday 29 ApriL. Ground truth
measurements were made near the buoy with hand-held standards. A chronology
of important events during deployment and recovery operations and documentation
of ground truth data follows.
26 April 1991
0850Z Begin buoy compass spin.
1022Z Finish spin (see Figure 17).
1029Z Chart-recorder tensiometer (SN 278) turned on.
1105Z Pulled 500 Lbs on tensiometer 278 for one minute.
1500Z Discus buoy moved from indoors to outdoors (Outside air temp = +4°C).
1624Z Both VAWR Sea Temp probes placed in bucket of ice water, remained in
water overnight.
112
1600Z Begin pre-deployment ground truth observations.
WSPD(m/s)
BP(mb)
RH(%)
AT(C)
1600Z (26 April)1800Z1915Z2248Z0730Z (27 April)
7-105-85-81-21-2
995.4 69.0 +5.5
993.2 75.5 +4.6
992.4 77.4 +4.7
989.5 78.9 +5.2
986.5 68.8 +6.0
28 April 1991
1230Z Continued ground truth observations, note that comparison with buoy speed
wil not be valid because at this time the buoy is on its side on the deck of
the ENDEAVOR.
WSPD(m/s)
BP(mb)
RH AT(%) (C)
1230Z1630Z
1014.4 46.0 7.41016.6 47.9 8.3
6 September 1991
1130Z Begin pre-recovery ground truth observations. Measurements made with
hand-held sensors onboard ENDEAVOR approximately 1/4 mile downwind
from buoy. Ship's sail data also recorded.
113
Hand-held I Endeavor SAIL
Wet Dry BPI BP
RH(C) (C) (mb) (%)-(mb)
1130Z 13.50 14.4 1036.3 1035.5 93.4
1135Z 13.45 14.7 1036.3 1035.2 93.4
1140Z 13.40 14.5 1036.2 1035.2 93.4
1145Z 13.45 14.6 1036.2 1035.2 93.3
1150Z 13.40 14.3 1036.2 1035.1 93.3
1155Z 13.40 14.3 1036.2 1035.3 93.3
1200Z 13.40 14.3 1036.2 1035.2 93.2
1250Z Acoustic Release fired.
1900Z All mooring instrumentation, wire, and hardware aboard.
7 September 91
1302Z Ice-water bag held against lower thermistor on bridle (VAWR SN 706).
1334Z Ice bag off lower thermistor, transferred to upper thermistor (VAWR SN
184).
1415Z Ice bag off upper thermistor.
18 September 91
1221:00Z Pull on bridle tensiometer with come-along
1222:00Z Loosen come-along
1223:30Z Pull on bridle tensiometer with come-along
1223:00Z Loosen Com-along
114
1723Z 15 Temperature loggers from MLML mooring into walk-in reefer.
1840Z 15 Temperature loggers out of reefer, back in main lab.
22 September 91
1213:50- 1218Z Two MLML engineering instruments turned vertical (before and
after this period they were stored horizontally).
1227Z 12 Subduction NW Temperature loggers into walk-in Reefer.
1401Z 12 Subduction NW Temperature loggers out of walk-in, back in main lab.
..
115
Figure 18: Data from the pre-deployment buoy spin in Reykjavik, Iceland are shown.Compass readings from the two VAWRs (SN 184 and 706) are compared to a sightingpoint at a bearing of 0350.
116
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REPORT DOCUMENTATION 11. REPORT NO.PAGE WHOI-93-334. Title and Subtitle
The Marne Light - Mixed layer Experiment Cruise and Data ReportR/V Endeavor Cruise EN-224, Mooring Deployment, 27 April-l May 1991Cruise EN-227, Mooring Recovery, 5-23 SePtember 1991
7. Author(s) Albert J. Plueddemann, Robert A. Weller, Thomas D. Dickey, John Mar, George H.Tupper, Bryan S. Way, Wiliam M. Ostrom, Paul R. Bouchard, Andrea L. Oien, and Nancy R. Galbraith9. Performing Organization Name and Address
2. 3. Recipient's Accession No.
5. Report DateMay 1993
6.
8. Performing Organization Rept. No.WHO! 93-30
10. ProjectlaskIork Unit No.
The Wqøds Hole Oceanographic InstitutionWoods Hole, Massachusetts 02543
11. Contract(C) or Grant(G) No.
(C) NOOO14-89-J-1683
(G)
12. Sponsoring Organization Name and Address 13. Type of Report & Period Covered
Office of Naval Research Technical Report
14.
15. Supplementary Notes
This report should be cited as: Woods Hole Oceanog. Inst. Tech. Rept., WHOI-93-33.
16. Abstract (Limit: 200 words)
The Marne Light - Mixed Layer experiment took place in the sub-Arctic North Atlantic ocean, approximately 275 milessouth of Reykjavik, Iceland. The field program included a central surface mooring to document the temporal evolution of physical,biological and optical properties. The surface mooring was deployed at approximately 59°N, 21 oW on 29 April 1991 and recoveredon 6 September 1991. The Upper Ocean Processes Group of the Woods Hole Oceanographic Institution was responsible for design,preparation, deployment, and recovery of the mooring. The Group's contrbution to the field measurements included four differenttypes of sensors: a meteorological observation package on the surface buoy, a string of 15 temperature sensors along the mooringline, an acoustic Doppler current profier, and four instrments for measuring mooring tension and accelerations. The observationsobtained from the mooring are suffcient to describe the air-sea fluxes and the local physical response to surface forcing. Theobjective in the analysis phase wil be to determine the factors controlling this physical response and to work towards an under-standing of the links among physical, biological, and optical processes. This report describes the deployment and recovery of themooring, the meteorological data, and the subsurface temperature and current data.
17. Document Analysis a. Descriptors
1. air-sea interaction
2. upper ocean strcture
3. re-stratification
b. IdentifiersOpen-Ended Terms
c. COSA TI Field/Group
18. Availabilit Statement
Approved for publication; distribution unlimited.
19. Security Class (This Report)
UNCLASSIFIED21. No. of Pages
124
20. Security Class (This Page) 22. Price
(See ANSI-Z39.18) See Instructions on Reverse OPTIONAL FORM 272 (4-77)(Formerly NTIS-35)Department of Commerce
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