Project SANTA CLAµS
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Accomplishments & Reports: Physical Oceanography ProgramAnthony F. Amos University of Texas at Austin, Marine Science Institute Port Aransas, TX 78373 (afamos@utmsi.zo.utexas.edu) The physical oceanography program aboard R/V Polar Duke during the SANTA CLAµS cruise in December 1994 consisted of two parts; (1) vertical CTD/rosette profiles, and (2) continuous underway monitoring of ocean and atmospheric surface environmental conditions. This field report briefly describes the methodology used and preliminary results. CTD/rosette programA Sea-Bird Electronics model 9/11 Plus CTD with a General Oceanics 12-bottle rosette sampler was used to obtain continuous vertical density profiles of the water column, in most cases surface-to-bottom. Additional sensors provided dissolved oxygen, chlorophyll-a fluorescence, beam transmission, downwelling solar radiation (PAR), and light scattering profiles. Fifty-eight such profiles were obtained in the South Pacific, Crystal Sound, Lemaire Channel, Paradise Harbor and the Deception Island caldera. In addition, eleven rosette- mounted 12-liter "GO-FLO" sampling bottles were triggered on each station to collect water samples for the various researchers participating in SANTA CLAµS and for independent salinity and oxygen determinations. Dissolved oxygen was measured using a Sea-Bird (Beckman) oxygen sensor, fluorescence with a Chelsea fluorometer, beam transmission with a SeaTech 25-cm transmissometer, PAR with a Biospherical Instruments 4-π sensor and light scatter with a SeaTech model LS6000. The SANTA CLAµS underway systemThe goal of this program was to acquire essential information on the surface environment while the ship was underway and on-station so that surface expressions of frontal and biological boundaries could be mapped. The system acquires data from several different sensors and transducers which are part of the Polar Duke's IMET meteorological system and other instrumentation (GPS, gyro compass, bottom depth). With the able assistance of ET Dave Asselin, ASCII messages were provided from each of these systems which were acquired through a multi-port interface card. Real time data were displayed on the PC screen. The ship's LAN network was utilized to link computers and allow simultaneous recording of underway and CTD data on 150 MByte Bernoulli cartridges. Control was governed by a program written with the Professional Development BASIC BC7 system which performs the following tasks:
At midnight GMT a new file opens for receipt of the next day's data and records the previous day's file and certain values to the LAN and/or a diskette. This way data can be acquired by other users without interruption to the program. Two other processes are then initiated using a non-dedicated PC. First, a daily scientific log is printed showing all environmental parameters each hour of the day and whenever a comment was made. A daily summary sheet is printed showing the extremes and means of the major parameters, distance travelled, cumulative distance for cruise, and sun phenomena times. Finally, a daily plot of environmental parameters and ship's track is printed, similar to the real-time plotter output, but "cleaned up" and including times, positions, and designated numbers of all stations and other regular observations done on the cruise. |