Dataset: Sensor data from trace-metal clean (GTC) CTD rosette on the US GEOTRACES GP17-ANT cruise in the Amundsen Sea on RVIB Nathaniel B. Palmer (NBP2401) from November 2023 to January 2024

Water-column sensor data were collected during downcast deployments of a trace-metal clean CTD rosette ("GTC rosette") system. The GTC rosette casts were performed using the U.S. GEOTRACES trace-element rosette sampling system with a SeaBird Electronics (SBE) custom-built frame and carousel and 24 x 12 liter (L) GoFlo sampler bottles. The system included an SBE CTD unit with pressure sensor, temperature sensors, conductivity sensors and membrane oxygen sensor, as well as a transmissometer, chlorophyll-a fluorometer, altimeter, and turbidity sensor. The package was deployed on a sheathed conducting cable with a Vectran strength member using a Dynacon winch. Further details are provided in the GP17-ANT cruise report (Sedwick et al., 2024) and in the ODF cruise report (Scripps Institution of Oceanography Ocean Data Facility team, 2024).

Instrumentation Details:
The GTC rosette casts were performed with a package consisting of the U.S. GEOTRACES SBE trace-element rosette frame and carousel, and 24 x 12 L GoFlo sampler bottles. Underwater electronic components primarily consisted of an SBE-9plus housing unit with a Digiquartz pressure sensor, dual SeaBird SBE-3 temperature sensors and SBE-4C conductivity sensors, an SBE-43 membrane dissolved oxygen sensor, and a WetLabs C-Star transmissometer and ECO-FL-RTD chlorophyll-a fluorometer.

Sensors were calibrated during summer 2023, immediately prior to the GP17-ANT cruise, and the transmissometer was calibrated before the start and after the end of science operations. The GTC rosette also included a Benthos altimeter, which ceased functioning during the latter part of the cruise and was replaced with a Valeport altimeter borrowed from the shipboard USAP equipment, and a Seapoint turbidity sensor. The CTD data acquisition system consisted of an SBE-11plus deck unit and a networked generic PC workstation running Windows 10. SBE SeaSave7 v.7.26.7.121 software was used for data acquisition and to close bottles on the rosette. Further details are provided in the GP17-ANT cruise report (Sedwick et al., 2024) and in the ODF cruise report (Scripps Institution of Oceanography Ocean Data Facility team, 2024).

Note: Cruise reports are attached as Supplemental Files and available at https://usgeotraces.ldeo.columbia.edu/content/gp17-ant.