Raw data acquired by two thermosalinographs (SBE21, SeaBird GmbH) on board RV Polarstern were processed to yield a calibrated and validated data set of temperature, conductivity and salinity during expedition PS122/2. Both sensors were equipped with a more accurate external temperature sensor (SBE38, Sea-Bird GmbH). Data were downloaded from the DAVIS SHIP data base (https://dship.awi.de) with a resolution of 1 sec. The raw hex data were converted to temperature and conductivity while a sensor drift correction was applied using calibration coefficients from before and after the expedition. Salinity was calculated according to the instructions from the Practical Salinity Scale PSS-78, using the obtained (internal) temperature and conductivity data and a pressure of 11 dbar which represents the water depth of the inlet of the TSG system on Polarstern. Processed data are provided as 10min means of salinity and water temperature aligned with position data taken from master track of the respective cruise. A speed filter was not applied to the PS122 dataset because of the slow drift speed. This slow movement may lead to an overestimation of the mixed-layer temperature; in particular, small heat fluxes from the ship may raise the temperature in adjacent water in the lee, i.e. during times of drift in the direction opposite to the TSG inlet. The effect is expected to be small, but can potentially be higher than the accuracy of the temperature measurement. Further details and evaluation of the data is outlined in the data processing report found at the EPIC repository under URL (https://hdl.handle.net/10013/epic.7fffb528-06bd-48ae-8489-cea0444c4eab).

We thank Franziska Nehring (Fielax) for the processing of the data. We acknowledge the support of Winfried Markert and Olaf Hüttebräucker (Laeisz) for maintenance of the instruments on board. We appreciate the help of the PANGAEA team for their help in archiving the dataset.