Brief communication: Significant cold bias in ERA5 output for McMurdo region, Antarctica

Abstract. The ERA5 climate reanalysis dataset plays an important role in applications such as monitoring and modelling climate system changes in polar regions, so the calibration of the reanalysis to ground observations is of great relevance. Here, we compare the 2-meter air temperature time series of the ERA5 reanalysis to the near-ground air temperature measured in 17 Automatic Weather Stations in the McMurdo Sound, Antarctica. We find that the reanalysis data has a systematic cold bias of ~5 °C. Our results show that future work should rely on secondary observations to calibrate when using the ERA5 reanalysis in polar regions.