Brightness temperature offsets for the microwave radiometers HATPRO and MiRAC-P during Polarstern expeditions PS144 and PS149

Brightness temperature (TB) measurements of microwave radiometers (MWRs) HATPRO (Humidity and Temperature PROfiler, 22-58 GHz, [1]) and MiRAC-P (Microwave Radar/Radiometer for Arctic Clouds - Passive, 183-340 GHz, [2]) can be biased due to imperfect absolute calibrations. This data set contains TB offsets for each microwave radiometer for the sideuser projects VAMPIRE-1 and VAMPIRE-2, which were conducted during the expeditions PS144 [3] and PS149 [4] of the research vessel Polarstern. The TB offsets were determined using radiative transfer simulations using the Passive and Active Microwave radiative TRAnsfer model (PAMTRA, [5]) of clear sky radiosondes that were compared to co-located MWR observations. For more details, see [6]. Recommendation: Please use only the bias correction and not the linear fit correction. [1]: Rose, T., Crewell, S., Löhnert, U., and Simmer, C.: A network suitable microwave radiometer for operational monitoring of the cloudy atmosphere, Atmospheric Research, 75, 183-200, https://doi.org/10.1016/j.atmosres.2004.12.005, 2005. [2]: Mech, M., Kliesch, L.-L., Anhäuser, A., Rose, T., Kollias, P., and Crewell, S.: Microwave Radar/radiometer for Arctic Clouds (MiRAC): first insights from the ACLOUD campaign, Atmospheric Measurement Techniques, 12, 5019-5037, https://doi.org/10.5194/amt-12-5019-2019, 2019. [3]: Rabe, B., and Geibert, W.: The Expedition PS144 of the Research Vessel POLARSTERN to the Arctic Ocean in 2024, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Berichte zur Polar- und Meeresforschung = Reports on polar and marine research, 794, 1-312, edited by Bornemann, H., and Sawadkuhi, S. A., https://doi.org/10.57738/BzPM_0794_2025, 2025. [4]: ADD WHEN AVAILABLE [5]: Mech, M., Maahn, M., Kneifel, S., Ori, D., Orlandi, E., Kollias, P., Schemann, V., and Crewell, S.: PAMTRA 1.0: the Passive and Active Microwave radiative TRAnsfer tool for simulating radiometer and radar measurements of the cloudy atmosphere, Geoscientific Model Development, 13, 4229–4251, https://doi.org/10.5194/gmd-13-4229-2020, 2020. [6]: ADD CITATION OF PAPER WHEN AVAILABLE