Temperature and salinity profiles from a free-falling profiler during POLARSTERN cruise PS138

Vertical profiles of in-situ temperature and practical salinity were obtained by a free-falling prope (MSS90 by Sea & Sun Technology), launched through holes in sea ice. Measured variables were conductivity, temperature and pressure (CTD). Practical salinity and depth were derived using TEOS10. The probe was linked to a surface field laptop by a loose, conducting tether and and an electric winch with a slip ring for data transmission. Geographic position and time was recorded simultaneous to deployments by a GPS interfaced with the laptop. The positions for PS138_152_MSS_1 and PS138_152_MSS_2 only were set to one value each day, based on one position of Polarstern, as the field GPS did not work correctly. The data are preliminary, with an accuracy of 0.05 in practical salinity. They only cover the upper 15 m of each profile and are averaged in time during each ice station for the duration of deployment of other sensors measuring in the boundary layer directly under the sea ice. The final data set and the accompanying turbulence data will be published in the future. Further details can be found in the PS138 expedition report that is currently in production.