Temperature and heating induced temperature difference measurements were recorded by several SIMBA-type sea ice mass balance buoys (IMBs) deployed during RV Polarstern expedition PS138 to the central Arctic Ocean in August – September 2023. The profiles were obtained in the atmosphere, snow, ice, and ocean along a 4.8 m long thermistor chain with 240 thermistors at 0.02 m spacing, deployed on selected ice floes during ship-based ice stations. The data were transferred to a land-based server via the iridium satellite network. The measurement interval for the temperature measurements was typically 6 h, whereas the heating cycle was performed once per day at midnight. Auxiliary data include 1 m air temperature, GPS position, compass heading, and instrument tilt. This entry consists of a preprocessed sub-dataset from 6 out of 11 deployed units, and includes data from initial deployment in August/September 2023 until early April 2024, when some of the buoys were still operational. The data provided here was downloaded from www.meereisportal.de on 11 April 2024, and is a result of the standard processing at that date without further modification. A fully processed and quality-controlled dataset of all PS138 SIMBA buoys will be made available and linked to after the buoys have stopped reporting.

We acknowledge the chief scientist Antje Boetius, as well as the captain, crew, and scientific staff of Polarstern expedition PS138 for their great field support. We are grateful to Christina Bienhold, Frederic Tardeck, Julia Regnery, and Annekathrin Jäkel for their help with the (meta)data management.