Raw physical oceanography data was acquired by a ship-based Seabird SBE911plus CTD-Rosette system onboard RV POLARSTERN during research cruise PS131 (ATWAICE: ATlantic WAter pathways to the ICE). The CTD was equipped with duplicate sensors for temperature (SBE3plus), conductivity (SBE4) and oxygen (SBE43). Additional sensors such as a WET Labs C-Star transmissometer, a WET Labs ECO-AFL fluorometer (FLRTD), a CDOM WET Labs ECO-FL fluorometer (FLRTD), a PAR sensor (SeaBird PARLOG) and an altimeter (Teledyne Benthos PSA-916) were mounted to the CTD. The data was recorded using pre-cruise calibration coefficients. No correction, post-cruise calibration or quality control was applied. For the Aurora cast (PS131_075_01), the PAR sensor was removed to include a Seapoint Turbidity Sensor to facilitate the detection of hydrothermal plumes. Independent sensors such as an Underwater Vision Profiler (UVP5 DEEP) and a Lowered ADCP system (RDI LADCP) were attached to the CTD-Rosette system and operated during most of the casts. For all casts shallower than 2000 m a nitrate sensor (Satlantic SUNA) was attached. For data availability see cruise report. A PDF with scans of the handwritten protocols is included in this publication as zip file. The processed dataset will be linked below upon completion.

For a total of 4 stations, casts were numbered differently from the ship's official ActionLog. We kept the original numbering here to avoid further confusion. The cast names will be changed in the processed dataset to match the station numbers in the ship's ActionLog Station number in CTD protocols and header -> Station number as logged by the ship010_02 -> 011_01037_01 -> 036_01037_02 -> 037_01099_01 -> 100_01