Reproduction in whole or in part is permitted for any purpose of the United States Government. This report should be cited as: Woods Hole Oceanog. Inst. Tech. Rept., WHOI-91-19.Approved for publication; distribution unlimited.
Approved for Distr./ James Luyten, Chairman June 24 -July 9, 1990
Department of Physical Oceanography
InstrumentationThree EG&G/Neil Brown Instrument Systems (NBIS) MK nIb CTDs were used as the primar profing instruents aboard US /PRC cruises 5-8. The three instruments (serial numbers 1104 (CTD 11), 1125 (CTD 12), and 2233' (CTD 13)) sampled temperature, conductivity, pressure and dissolved oxygen. A detailed description of this instrument can be found in the report by Brown and Morrison (1978). A 12-position General Oceanics rosette fitted with 1.7 liter Niskin bottles was used to collect water samples for subsequent analysis aboard the vessel. Digital CTD data were acquired with a NBIS 1150 deck unit. These raw data were archived with a PC based system (using the EG&G Marne Instruments Oceansoft CTD acquisition software) for real time display and subsequent data processing. Figure 2 shows a schematic of the equipment employed.Water samples from the rosette sampler were analyzed for salinity and dissolved oxygen content. Salnity samples were analyzed on a Chinese salinometer similar to the Australian Autolab. Dissolved oxygen samples were analyzed using a modified Winkler method, all of the titration equipment was supplied by SOA, and all of the samples were processed by PRC technicians.
Data CollectionA series of zonal and meridional transects, with stations positioned to optimize the resolution of transport in the strong current regions near the equator and the coasts, were occupied durng these cruises. Each cruise consisted of six major sections. Zonal sections were occupied along 18°20'N, 8°N, and the equator (on cruse 8, a lOON section was also occupied). Meridional sections were occupied along 130oE, 141°30'E, and 165°E(se Figure i).Durg cruse 5 the standard station depth of 3500 m was obtained with several stations reachng a maximum depth of 5000 m. On cruse 6, the station depths went to 5000 m or within 5~100 m of the bottom. During cruise 7, station depths reached a maximum depth of 3500 m. On cruse 8 the station depths alternated between 3500 and 5000 m or within 50-100 m of the bottom depending upon ocean depth and the strength of the current. The PRC vessel had a liited abilty to maneuver on the wire, thus, strong winds or currents resulted in large wire angles, limiting cast depths.Thirteen stations were not completed on cruse 5 due to adverse weather conditions. The loss of CTD 12 and failure of the backup CTD 11 resulted in many missed stations on leg 1 of cruise 7. Despite these lost stations, the data return for cruises 5 -8 was excellent.
Data Calibration and ReductionConductivity, temperature and pressure sensors of the CTD instruments were calibrated at EG&G/NBIS and/or the WHOI calibration facilty prior to and following each cruise. Instrument sensor calibration...
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