Preliminary report
May 15, 1995
A. Cruise narrative
A.1 Highlights
A.1.a WOCE designation: PR20
A.1.b EXPOCODE 21OR257/1
A.1.c Chief Scientist: Cho-Teng Liu
Institute of Oceanography
National Taiwan University
Taipei POB 23-13, Taiwan, ROC 10764
e-mail: CtLiu@ccms.ntu.edu.tu
A.1.d Ship: Ocean Reseracher
A.1.e Ports of Call: Kaohsiung Harbor, Taiwan
A.1.f Cruise Dates: October 11 to October 15, 1990
A.2 Cruise Summary
A.2.a Geographic boundaries
A.2.b Total number of stations
A.2.c Floats and drifters deployed
A.2.d Moorings deployed or recovered
A.3 List of Principal Investigators
Table 1: List of Prinicipal Investigators
Name Responsibility Institution*
-------------------------------------------------------------------
LIU, Cho-Teng calibration, processing and NTU
interpretation of CTD and
ADCP data
PAI, Su-Cheng collection, analysis and NTU
interpretation of water
sample data
CHEN, Chen-Tung Arthur developing skills for NSYSU
collecting C-14 samples for
one-time survey
LIU, Kon-Kee: collection, analysis and AS
interpretation of water sample
data
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*See Table 2 for list of Institutions
Table 2: List of Institutions
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Abbreviation Institutions
----------------------------------------------------------------------
NTU National Taiwan University
Taipei, Taiwan, ROC 10764
NSYSU National Sun Yat-sen University
Kaohsiung, Taiwan, ROC
AS Academia Sinica
Taipei, Taiwan ROC 10764
A.4 Scientific Programme and Methods
The ship R/V Ocean Researcher 1 left Kaohsiung Harbor in souther Taiwan
at 10:30 am of 1990 October 11. After leaving the harbor for two nm, we re-
installed the ADCP in the Moon Pool near the center of the ship, which is near
the front part of the aft deck. We first sailed southwestward to recover a
month-long current meter mooring, then sailed to the first hydrographic
station of PR20. The weather was warm but very windy (northeasterly winter
monsoon), the sea state was so rough that the ship was sailing at 6 - 8.5
knots only, vs. 12.5 knots when the swell is low. It improved near the end of
PR20 section.
During the first four CTD stations, the wire angle was relatively large
because of the rough sea. This seems to correlate with the anomalous CTD
distribution and the derived geostrophic velocity near this region. Besides,
other problems are
(1) the conductivity data made jumps at st. 12-14 near 825 m depth, but they
behave well afterwards. All CTD data at st. 12-14 below the jump were thrown
out in post processing. After the cruise, SBEI found a crack in the
conductivity sensor. Every few stations, the water samples were taken for
salinity calibration;
(2) the DO data behaved abnormally since the first station due to bad contact
to the underwater unit. The connector was replaced and put back to work from
station 10;
(3) the effect of southwestward wind (winter monsoon) results 0.6-0.9 knots
ship drift towards west to northwestward, rather than northward along Kuroshio.
In addition to the WOCE hydrographic survey of repeated sections, we also tried
(1) improving our skill of water analysis in order to meet the requirement for
one time survey;
(2) taking some water samples for heavy metal analysis;
(3) taking CTD sections near PCM1 line NE of Taiwan, for the design of mooring
locations.
A.5 Major Problems and Goals not achieved
A.6 Other Incidents of Note
A.7 List of Cruise Participants
Table 3: List of Cruise Participants
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Name Responsiblity Institution*
------------------------------------------------------------------------------
LIU, Cho-Teng chief scientist NTU
PAI, Su-Cheng chief chemist NTU
GONG, Gwo-Ching nitrate analysis, chemical hydrography NTU
data processing NTU
LIN, Sheng-Fon CTD data processing NTU
YANG, Chung-Cheng silicate analysis NTU
JENG, Kwung-Lung phosphate analysis NTU
KUO, Ting-Yu dissolved oxygen analysis NTU
CHEN, Hung-Yu trace metal NTU
KUO, Jing-Sen pH analysis NSYSU
CHENG, Li-Lin alkalinity analysis NSYSU
------------------------------------------------------------------------------
*See Table 2 for list of Institutions
B. Underway Measurements
B.1 Navigation and bathymetry
B.2 Acoustic Doppler Current Profiler (ADCP)
B.3 Thermosalinograph and underway dissolved oxygen, fluorometer, etc
B.4 XBT and XCTD
B.5 Meteorological observations
B.6 Atmospheric chemistry
C. Hydrographic Measurements
D. Acknowledgments
E. References
Unesco, 1983. International Oceanographic tables. Unesco Technical Papers in
Marine Science, No. 44.
Unesco, 1991. Processing of Oceanographic Station Data, 1991. By JPOTS
editorial panel.
F. WHPO Summary
Several data files are associated with this report. They are the OR257.sum,
OR257.hyd, OR257.csl and *.wct files. The OR257.sum file contains a summary of
the location, time, type of parameters sampled, and other pertient
information regarding each hydrographic station. The OR257.hyd file contains
the bottle data. The *.wct files are the ctd data for each station. The *.wct
files are zipped into one file called OR257wct.zip. The OR257.csl file is a
listing of ctd and calculated values at standard levels.
The following is a description of how the standard levels and
calculated values were derived for the OR257.csl file:
Salinity, Temperature and Pressure: These three values were smoothed from
the individual CTD files over the N uniformly increasing pressure levels
using the following binomial filter-
t(j) = 0.25ti(j-1) + 0.5ti(j) + 0.25ti(j+1) j=2....N-1
When a pressure level is represented in the *.csl file that is not
contained within the ctd values, the value was linearly interpolated
to the desired level after applying the binomial filtering.
Sigma-theta(SIG-TH:KG/M3), Sigma-2 (SIG-2: KG/M3), and Sigma-4(SIG-4:
KG/M3): These values are calculated using the practical salinity scale
(PSS-78) and the international equation of state for seawater (EOS-80)
as described in the Unesco publication 44 at reference pressures of the
surface for SIG-TH; 2000 dbars for Sigma-2; and 4000 dbars for Sigma-4.
Gradient Potential Temperature (GRD-PT: C/DB 10-3) is calculated as the
least squares slope between two levels, where the standard level is the
center of the interval. The interval being the smallest of the two
differences between the standard level and the two closest values.
The slope is first determined using CTD temperature and then the
adiabatic lapse rate is subtracted to obtain the gradient potential
temperature. Equations and Fortran routines are described in Unesco
publication 44.
Gradient Salinity (GRD-S: 1/DB 10-3) is calculated as the least squares
slope between two levels, where the standard level is the center of the
standard level and the two closes values. Equations and Fortran
routines are described in Unesco publication 44.
Potential Vorticity (POT-V: 1/ms 10-11) is calculated as the vertical
component ignoring contributions due to relative vorticity, i.e.
pv=fN2/g, where f is the coriolius parameter, N is the bouyancy
frequency (data expressed as radius/sec), and g is the local
acceleration of gravity.
Bouyancy Frequency (B-V: cph) is calculated using the adiabatic
leveling method, Fofonoff (1985) and Millard, Owens and Fofonoff
(1990). Equations and Fortran routines are described in Unesco
publication 44.
Potential Energy (PE: J/M2: 10-5) and Dynamic Height (DYN-HT: M) are
calculated by integrating from 0 to the level of interest. Equations and
Fortran routines are described in Unesco publication, Processing of
Oceanographic station data.
Neutral Density (GAMMA-N: KG/M3) is calculated with the program GAMMA-N
(Jackett and McDougall) version 1.3 Nov. 94.
G. Data Quality Evaulation
.