This Level 3 dataset of radiosondes launched during the MOSAiC expedition has been processed by the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) algorithm for RS41 radiosonde data. The GRUAN processing is based on the extensive characterisation of the sensor properties to produce a traceable reference data product which is free of manufacturer-dependent effects. Uncertainty values are provided for all measured parameters at all height levels. It should be noted that all provided height information is obtained from the GPS measurement. Close to buildings and metal surfaces (such as RV Polarstern) GPS signals are often very noisy, resulting in artifacts in the vertical elevation coordinate close to the surface. In the atmospheric boundary layer, it is therefore recommended to rely on height calculations based on pressure.Please note that the TAB-delimited ascii format data present only a subset of parameters. The complete GRUAN-processed data are available in the linked netCDF files.