The description below is excerpted from the GP15 Cruise Report (PDF). Refer to cruise report for more information, including the complete problem report and CTD processing details.
The 36-place Scripps Ocean Data Facility (ODF) rosette was used to sample water for less contamination-prone elements. Casciotti (Stanford, co-cruise leader), along with Marty Fleisher (LDEO) and Colette Kelly (Stanford) were responsible for managing the water budget and overall sampling of the ODF rosette. The ODF group was responsible for maintenance and calibration of the rosette bottles and instrumentation.
Cast types included 'Demi' station casts to 1000 m, shallow casts to 400-1000m, intermediate casts from 400-2000 m, and deep casts to within 40 m of the bottom. At each full and super station, an additional cast of the ODF rosette was conducted to sample large volumes for pigments, Radium, and Thorium isotopes (PigRaTh). On the PigRaTh casts, eight depths were selected to match the shallowest eight pump depths. Another four depths were chosen for resolution of Th-234, and a surface bottle was tripped for a 13th sample depth. The surface bottle was used primarily to sample dissolved gases at the sea surface, rather than drawing from the towfish or the ship's underway system. Surface bottle sampling also occurred at demi stations (13 depths sampled instead of 12).
CTDO/rosette casts were performed with a package consisting of a 36 bottle rosette frame, a 36-place carousel and 36 Bullister style Niskin bottles with an absolute volume of 10.6L. Underwater electronic components primarily consisted of a SeaBird Electronics housing unit with Paroscientific pressure sensor with dual plumbed lines where each line has a pump, temperature sensor, conductivity sensor, and exhaust line. A SeaBird Electronics membrane oxygen sensor was mounted on the "primary" line. A reference thermometer, transmissometer, chlorophyll-a fluorometer and backscatter meter, oxygen optode, altimeter and for some casts, a monocore were also mounted on the rosette.
©2020 Biological and Chemical Oceanography Data Management Office.