A.    Cruise Narrative: PR23, PCM11 The Samoan Passage Experiment

A.1.  Highlights
                         WHP Cruise Summary Information

                     WOCE section designation  PR23, PCM11
            Expedition designation (EXPOCODE)  316N138_8
     Chief Scientist(s) and their affiliation  R.D.Pillsbury/OSU,
                                               Daniel L. Rudnick/UW
                                        Dates  1992.SEP.15 - 1992.SEP.27
                                         Ship  R. V. Knorr
                           Number of stations  12
                 Floats and drifters deployed  6 ALACE floats
               Moorings deployed or recovered  6


Scientific Goals

The central goal of the project is to determine the northward transport of 
abyssal water through the Samoan Passage, which appears to be the major pathway 
through which water deeper than 4000 m can go from the South Pacific to the 
North Pacific. An estimate of this transport is crucial to an understanding of 
abyssal circulation in the Pacific. Additional goals are to estimate the flux of 
heat, salt, oxygen and nutrients through the Samoan Passage, and to observe the 
low frequency variability in the transport.

Cruise Objectives

The main objective of the cruise was to deploy six subsurface moorings 
instrumented with current meters from 3000 m to the bottom. In support of this 
objective, twelve full-depth CTD casts were made to obtain the temperature-
salinity characteristics of the abyssal water. In addition, six neutrally 
buoyant floats, called Autonomous Lagrangian Circulation Explorers (ALACE), were 
deployed. Bathymetry was collected while underway over the Robbie Ridge and 
Samoan Passage.

The six subsurface moorings were deployed along a transect in the Samoan Passage 
(Table 1, Figures 1-3). Each mooring had a radio buoy at the top, current 
meters, glass balls for flotation, an acoustic release, and an anchor. A total 
of 27 current meters were deployed, each measuring horizontal current and 
temperature. The upper two current meters on each mooring had pressure sensors. 
The moorings are due to be recovered in September 1994.

A total of 27 Aanderaa RCM8 current meters were employed, each measuring
horizontal current and temperature, with the upper two meters on each
mooring also measuring pressure. All instruments were recovered. There were
some failures:

   * Instrument 5872, the top meter of Mooring 2, experienced an electronic
     board failure after 5 days and stopped recording data. The data from
     this meter are not presented here.
   * The pressure sensor on Instrument 4412 (2990 m on Mooring 1) showed
     abrupt depth changes several times. We believe these to be spurious,
     due to a sensor failure.
   * The temperature sensor of Instrument 5856 (2970 m on Mooring 6)
     malfunctioned after 9 months.
   * The compass of Instrument 7769 (4900 m on Mooring 3) failed its
     post-cruise calibration. It appears that the failure occured
     approximately one-fourth of the way through the experiment. Because the
     data are vector averages, both speed and direction are suspect.

The quality of the remaining records was excellent.

Table 1. Mooring positions.

  Mooring  Latitude    Longitude
  -------  --------    -----------
     1      9°41.12'S  170°28.13'W
     2      9°50.34'S  169°59.23'W
     3      9°55.08'S  169°44.35'W
     4     10°00.13'S  169°29.42'W
     5     10°05.13'S  169°14.72'W
     6     10°13.21'S  168°50.00'W

Of the twelve CTD casts, one was done north of a gap in the Robbie Ridge, and 
eleven were done in the Samoan Passage (Table 2). These casts provided 
measurements of temperature, conductivity, pressure, and oxygen from the bottom 
to the surface. Water samples were taken to calibrate the CTD conductivity 
sensor, although the oxygen sensor was not calibrated. The second component of 
the Samoan Passage Experiment is WOCE hydrographic line P31, from Fiji to Tahiti 
via the Robbie Ridge and Samoan Passage. This line is to be done by Dean 
Roemmich before the current meters are recovered, and is to include the full 
suite of WOCE hydrographic measurements.

Table 2. CTD stations.

  Station  Latitude   Longitude
  -------  --------   ----------
     1     9°30.3' S  174°44.5'W
     2     10°13.3'S  168°52.9'W
     3     10°09.01S  169°01.9'W
     4     10°05.2'S  169°14.7'W
     5     10°02.5'S  169°22.0'W
     6      9°59.6'S  169°32.6'W
     7      9°57.4'S  169°37.0'W
     8      9°50.0'S  170°02.1'W
     9      9°51.9'S  169°51.8'W
    10      9°54.6'S  169°47.1'W
    11      9°41.0'S  170°31.1'W
    12      9°45.4'S  170°13.8'W

Six ALACEs were launched: one north of the Robbie Ridge, three in the Samoan 
Passage, and two east of the Manihiki Plateau (Table 3). The ALACEs, deployed 
for Russ Davis, were designed to float at 1500 m and to cycle to the surface 
every 26 days to report positions and temperature profiles. The ALACEs are 
expected to continue cycling for three to four
years.

Table 3. ALACE deployments.

  Serial Number  Latitude    Longitude
  -------------  ----------  -----------
       177        9°31.44'S  174°43.99'W
       178       10°12.77'S  168°53.04'W
       181        9°54.64'S  169°44.38'W
       171        9°40.80'S  170°30.94'W
       172       13°55.44'S  159°46.09'W
       173       15°46.92'S  154°56.63'W


Robbie Ridge

The original plan was to deploy five moorings in the Samoan Passage near 10°S, 
170°W, and one mooring in a gap in the Robbie Ridge at 10°05'S, 174°10'W. Having 
departed Suva, Fiji at 050OZ 15 September, the first mooring deployment was to 
have been at the Robbie Ridge (Figures 1 and 2). A bathymetric survey was begun 
at 1645Z 17 September and terminated at 0718Z 18 September. The gap in the 
Robbie Ridge was approximately 4200 m deep and several miles wide amid very 
rough topography. Because the gap was so small, we determined that it could not 
be a major pathway for water colder than 1°C and did not deploy a mooring.

A CTD station was occupied north of the Robbie Ridge at 09°30.3'S, 174°44.5'W to 
look for evidence of abyssal water flowing over the ridge. The coldest water at 
this 4525 m deep station had a potential temperature of 0.87°C, so little 
abyssal water was flowing through the gap. After deploying ALACE 177 we headed 
for the Samoan Passage.


Samoan Passage

We arrived at the Samoan Passage at 0838Z 19 September and began a bathymetric 
survey consisting of a transect of the passage. After the transect was completed 
at 2220Z, we determined mooring positions on the basis of the bathymetry (Table 
1, Figure 3). The horizontal spacing of the array in the center of the Passage 
was about 28 km.

During the four days on station in the Samoan Passage, our general plan was to 
deploy moorings during the day and to do CTD casts at night. This plan took 
advantage of the daylight for mooring operations, and allowed time for eleven 
CTD casts: six casts next to the moorings, and five between the moorings. Three 
ALACEs were deployed in the passage.

The moorings were designated 1 through 6 from west to east. Since the 
bathymetric survey left us on the east side of the passage, we began with 
mooring 6. Prior to each mooring deployment a small-scale bathymetric survey 
consisting of a box, one mile on a side, was done around each mooring site. Fine 
adjustments in mooring positions were made using the results of these surveys. 
Following each deployment, a survey was done to determine the position of the 
acoustic release.

Deployment of mooring 6 began at 0145Z and concluded at 0326Z 20 September 
(1626LT). CTD stations 2-4 were done during the evening: CTD 2 was three miles 
off (to avoid tangling) from mooring 6, CTD 3 was between moorings 5 and 6, and 
CTD 4 was at mooring site 5. ALACE 178 was launched upon the conclusion of CTD 
station 2.

Mooring 5 was deployed during 1806Z-1952Z 20 September, and mooring 4 was 
          deployed during 011OZ-0309Z 21 September. CTD stations 5-7 were done 
          during the evening: CTD 5 was between moorings 4 and 5, CTD 6 was 
          three miles off from mooring 4, and CTD 7 was between moorings 3 and 
          4.

Mooring 3 was deployed during 1931Z-2154Z 21 September, and mooring 2 was 
          deployed during 0152Z-0348Z 22 September. ALACE 181 was deployed after 
          mooring 3. The evening's CTD stations were 8-10: CTD 8 was three miles 
          off from mooring 2, CTD 9 was between moorings 2 and 3, and CTD 10 was 
          three miles off from mooring 3.

Mooring 1 was deployed from 2341Z 22 September to 0046Z 23 September. CTD 
          station 11 was three miles off from mooring 1, and CTD 12 was between 
          moorings 1 and 2. ALACE 171 was launched after CTD 11.

Having finished all the mooring deployments and CTD casts, we headed back along 
the transect and resurveyed the acoustic releases on moorings 3 and 6. These 
additional surveys were necessary because of intermittent failures in the 
acoustic release deck box.

At 2044Z 23 September the resurvey of mooring 6 was completed and we were 
underway to Papeete, Tahiti. ALACEs 172 and 173 were launched on the way.

We arrived in Papeete at 0235Z 28 September.


Personnel

Daniel Rudnick,  University of Washington
Dennis Root,     Oregon State University
Robert Still,    Oregon State University
John Simkins,    Oregon State University
Dennis Barstow,  Oregon State University
Mary Johnson,    Scripps Institution of Oceanography
Scott Hiller,    Scripps Institution of Oceanography
Wendi Eastman,   University of Washington
Christine Halas, University of Washington

Acknowledgments

I would like to thank Captain Chiljean and the crew of the R/V Knorr for their 
help, especially during mooring deployments. It was a pleasure to sail with such 
an able and professional science party. This cruise was sponsored by the 
National Science Foundation under grant OCE-9104161.





Log

Date    Time  Latitude    Longitude    Event
         (Z)
------  ----  ----------  -----------  ----------------------------------------
15 Sep  0500  18°07.86'S  178'24.83'E  Depart Suva
17 Sep  1645  10°34.88'S  174°36.23'W  Begin bathymetric survey at Robbie Ridge
18 Sep  0718  09°44.61'S  175°00.28'W  Terminate bathymetric survey
        0950  09°30.04'S  174°44.07'W  Start CTD station #1
        1233  09°31.39'S  174°44.31'W  End CTD station #1
        1243  09°31.44'S  174°43.99'W  Launch ALACE #177
19 Sep  0838  09°30.09'S  171°00.00'W  Begin bathymetric survey at Samoan 
                                       Passage
        2220  10°20.81'S  168°28.71'W  End bathymetric survey
20 Sep  0145  10°12.96'S  168°51.35'W  Begin deployment of mooring #6
        0326  10°13.38'S  168°49.93'W  Anchor away for mooring #6
        0533  10°13.50'S  168°52.96'W  Start CTD station #2
        0817  10°12.98'S  168°53.09'W  End CTD station #2
        0829  10°12.77'S  168°53.04'W  Launch ALACE #178
        0934  10°09.10'S  169°02.19'W  Start CTD station #3
        1212  10°09.06'S  169°02.18'W  End CTD station #3
        1336  10°05.23'S  169°14.70'W  Start CTD station #4
        1631  10°05.22'S  169°14.61'W  End CTD station #4
        1806  10°04.94'S  169°17.68'W  Start deployment of mooring #5
        1952  10°05.12'S  169°14.62'W  Anchor away for mooring #5
21 Sep  0110  09°59.13'S  169°32.82'W  Start deployment of mooring #4
        0309  10°00.21'S  169°29.38'W  Anchor away for mooring #4
        0610  10°02.94'S  169°21.91'W  Start CTD station #5
        0902  10°02.25'S  169°22.34'W  End CTD station #5
        1016  10°00.08'S  169°32.34'W  Start CTD station #6
        1331  09°59.01'S  169°32.87'W  End CTD station #6
        1420  09°57.46'S  169°37.00'W  Start CTD station #7
        1714  09°57.56'S  169°37.58'W  End CTD station #7
        1931  09°55.15'S  169°48.41'W  Start deployment of mooring #3
        2154  09°55.15'S  169°44.28'W  Anchor away for mooring #3
        2313  09°54.64'S  169°44.38'W  Launch ALACE #181
22 Sep  0152  09°50.40'S  170°02.68'W  Start deployment of mooring #2
        0348  09°50.41'S  169°59.22'W  Anchor away for mooring #2
        0643  09°50.35'S  170°02.17'W  Start CTD station #8
        0929  09°49.19'S  170°01.86'W  End CTD, station #8
        1042  09°52.82'S  169°52.15'W  Start CTD station #9
        1336  09°51.18'S  169°51.56'W  End CTD station #9
        1425  09°55.17'S  169°47.04'W  Start CTD station # 10
22 Sep  1722  09°53.99'S  169°46.80'W  End CTD station 410
        2341  09°41.13'S  170°30.08'W  Start deployment of mooring #1
23 Sep  0046  09°41.10'S  170°30.08'W  Anchor away for mooring #1
        0331  09°41.10'S  170°31.12'W  Start CTD station #11
        0554  09°40.80'S  170°31.18'W  End CTD station #11
        0605  09°40.80'S  170°30.94'W  Launch ALACE #171
        0755  09°45.30'S  170°13.59'W  Start CTD station #12
        1015  09°45.46'S  170°14.03'W  End CTD station #12
25 Sep  1821  13°55.44'S  159°46.09'W  Launch ALACE #172
26 Sep  1817  15°46.92'S  159°56.63'W  Launch ALACE #173
28 Sep  0235  17°27.84'S  149°36.52'W  Arrive Papeete



CTD Data

Potential temperature, salinity, and potential density for each of the twelve 
CTD stations are shown in the following plots. The location, bottom depth and 
time are given for each station.

PCM11 discrete salts comments

001/01  bottle 24: lanyard hung up, no sample
002/01  bottle 20: lanyard hung up, no sample
002/01  ALL differences +.01 compared to ctd; only cast this high; not rerun
003/01  end standard drift +.00023
004/01  huge end drift (+160) - RERUN looks fine
005/01  ok
006/01  bottle 20: lanyard hung up, no sample
007/01  ok
008/01  ok
009/01  see station 10 - not rerun
010/01  bottle 20: lanyard hung up, no sample
010/01  run back to back with 9; large drift (+53) - RERUN looks fine
011/01  bottle 116 salt looks low
012/01  ok

a "D" in the differences report next to bottle salinity means the salinity
value is the CTD salinity - no difference will be reported.  These bottles
were mis-trips and came back with no water.  All data values were included
in the report, even if they were questioned or not used for ctd calibration.


June 2001

ODF has discovered a small error in the algorithm used to convert
ITS90 temperature calibration data to IPTS68.  This error affects
reported Mark III CTD temperature data for most cruises that occurred
in 1992-1999.  A complete list of affected data sets appears below.

ODF temperature calibrations are reported on the ITS90 temperature
scale.  ODF internally maintains these calibrations for CTD data
processing on the IPTS68 scale.  The error involved converting ITS90
calibrations to IPTS68.  The amount of error is close to linear with
temperature: approximately -0.00024 degC/degC, with a -0.00036 degC
offset at 0 degC.  Previously reported data were low by 0.00756 degC
at 30 degC, decreasing to 0.00036 degC low at 0 degC.  Data reported
as ITS90 were also affected by a similar amount.  CTD conductivity
calibrations have been recalculated to account for the temperature
change.  Reported CTD salinity and oxygen data were not significantly
affected.

Revised final data sets have been prepared and will be available soon
from ODF (ftp://odf.ucsd.edu/pub/HydroData).  The data will eventually
be updated on the whpo.ucsd.edu website as well.

IPTS68 temperatures are reported for PCM11 and Antarktis X/5, as
originally submitted to their chief scientists.  ITS90 temperatures
are reported for all other cruises.

_______________________________________________________________________

Changes in the final data vs. previous release (other than temperature
and negligible differences in salinity/oxygen):

S04P: 694/03 CTD data were not reported, but CTD values were reported
      with the bottle data.  No conductivity correction was applied
      to these values in the original .sea file.  This release uses
      the same conductivity correction as the two nearest casts to
      correct salinity.

AO94: Eight CTD casts were fit for ctdoxy (previously uncalibrated)
      and resubmitted to the P.I. since the original release.  The
      WHP-format bottle file was not regenerated.  The CTDOXY for
      the following stations should be significantly different than
      the original .sea file values:
      009/01  013/02  017/01  018/01  026/04  033/01  036/01  036/02

I09N: The 243/01 original CTD data file was not rewritten after
      updating the ctdoxy fit.  This release uses the correct
      ctdoxy data for the .ctd file.  The original .sea file was
      written after the update occurred, so the ctdoxy values
      reported with bottle data should be minimally different.

========================================================================

DATA SETS AFFECTED:          
          


WOCE FINAL DATA - NEW RELEASE AVAILABLE:          
          
WOCE Section ID     P.I.                 Cruise Dates
--------------------------------------------------------
S04P               (Koshlyakov/Richman)  Feb.-Apr. 1992
          
P14C               (Roemmich)            Sept. 1992
PCM11              (Rudnick)             Sept. 1992
P16A/P17A (JUNO1)  (Reid)                Oct.-Nov. 1992
P17E/P19S (JUNO2)  (Swift)               Dec. 1992 - Jan. 1993
P19C               (Talley)              Feb.-Apr. 1993
P17N               (Musgrave)            May-June 1993
P14N               (Roden)               July-Aug. 1993
P31                (Roemmich)            Jan.-Feb. 1994
          
A15/AR15           (Smethie)             Apr.-May 1994
          
I09N               (Gordon)              Jan.-Mar. 1995
I08N/I05E          (Talley)              Mar.-Apr. 1995
I03                (Nowlin)              Apr.-June 1995
I04/I05W/I07C      (Toole)               June-July 1995
I07N               (Olson)               July-Aug. 1995
I10                (Bray/Sprintall)      Nov. 1995
          
ICM03              (Whitworth)           Jan.-Feb. 1997
          


NON-WOCE FINAL DATA - NEW RELEASE AVAILABLE:          
          
Cruise Name         P.I.                 Cruise Dates
--------------------------------------------------------
Antarktis X/5      (Peterson)            Aug.-Sept. 1992
Arctic Ocean 94    (Swift)               July-Sept. 1994
          


PRELIMINARY DATA - WILL BE CORRECTED FOR FINAL RELEASE ONLY
                   NOT YET AVAILABLE:          
          
Cruise Name         P.I.                 Cruise Dates
--------------------------------------------------------
WOCE-S04I          (Whitworth)           May-July 1996
          
Arctic Ocean 97    (Swift)               Sept.-Oct. 1997
HNRO7              (Talley)              June-July 1999
KH36               (Talley)              July-Sept. 1999
          


"FINAL" DATA FROM CRUISE DATES PRIOR TO 1992, OR CRUISES 
             WHICH DID NOT USE NBIS CTDS, ARE NOT AFFECTED.
          


POST-1991 PRELIMINARY DATA NOT AFFECTED:          
          
Cruise Name         P.I.                 Cruise Dates
--------------------------------------------------------
Arctic Ocean 96    (Swift)               July-Sept. 1996
WOCE-A24 (ACCE)    (Talley)              May-July 1997
XP99               (Talley)              Aug.-Sept. 1999
KH38               (Talley)              Feb.-Mar. 2000
XP00               (Talley)              June-July 2000



Jun 2001

>>REVISED FINAL quality-coded WHP-format CTDO + Bottle Data release for
  WOCE92-PCM11

These data were revised to correct a temperature conversion error.
Please see the file DOC/README.Jun2001 for more information regarding
this error and its correction.  This is the first release of these
data in WHP standard format.

The CTD data in this release have been corrected using pre- and post-cruise
laboratory calibrations for pressure and temperature, and bottle salt vs CTD
comparisons to calibrate conductivity/salinity.  Interpolated/extrapolated
data records are identified by a quality code of "6666".  Only surface
(0-decibar) levels may have been extrapolated in this data set.  The
default quality code of "2" (acceptable) was used for CTD Pressure,
Temperature and Salinity.

CTD oxygen data are quality-coded "1" (uncalibrated) because no bottle
oxygen samples were drawn or analyzed.  CTD oxygens cannot be corrected
without check sample data taken during the casts.  The shipboard oxygen
corrections from P14C/station 37, during the leg which preceded this cruise,
were used for all casts in order to provide some idea of approximate maxima
and minima only.  These CTD oxygen data should in no way be used to draw any
conclusions about oxygen for these casts.

The only bottle data collected during PCM11 were salinity check-samples
for the purpose of calibrating CTD salinity.  A WOCE-format ".sea" file with
bottle salinities and standard CTDO values is included with this release.
Further documentation, including data processing details and problems or
tables of correction coefficients, will not be produced for this cruise.
Wilf Gardner at TAMU (wgardner@tamu.edu) should be contacted regarding
any transmissometer data collected with PCM11 CTD casts.



QUESTIONS:

Chief Scientist/PI:
    Dr. Daniel Rudnick
    PORD M.C. 0230
    Scripps Institution of Oceanography
    UC San Diego
    9500 Gilman Drive
    La Jolla, CA 92093-0230
    phone: (858) 534-7669
    email: drudnick@ucsd.edu

Questions regarding the CTD data should be directed to:
    Mary Carol Johnson
    STS/ODF M.C. 0214
    SIO/UC San Diego
    9500 Gilman Drive
    La Jolla, CA 92093-0214
    phone: (858) 534-1906
    email: mary@odf.ucsd.edu

