Performance of surface radiation products of Greenland Ice Sheet using in-situ measurements

Radiation is the direct energy source of the surface natural environment and the main driving force of climate change. It has increasingly become an important meteorological factor affecting the surface heat exchange and glacier mass balance, especially in the glacier changes of the Greenland Ice Sheet(Gr IS). Due to the harsh climatic conditions of Gr IS and sparse observed data, it has become an important way to obtain radiation data from reanalysis datasets. However, the applicability of these radiation data on Gr IS is uncertain and worth exploring. In this work, we evaluate five reanalysis datasets(the fifth generation of European Centre for Medium-Range Weather Forecasts(ERA5), European Centre for Medium-Range Weather Forecasts Interim Reanalysis(ERA-Interim), Japanese 55-year Reanalysis(JRA55), National Centers for Environmental Prediction Reanalysis II(NCEP2) and Modern-Era Retrospective analysis for Research and Applications, Version 2(MERRA-2)) during 1997–2022 using observations from 26 Program for Monitoring the Greenland Ice Sheet(PROMICE) automatic weather stations(AWSs) and 3 K-transect AWSs on Gr IS. The conclusions are as follows: ERA5 has the best performances in downward shortwave radiation(SWD) as well as downward and upward longwave radiation(LWD and LWU), but the performance is not the best in upward shortwave radiation(SWU). Based on the radiation budget analysis with ERA5 during 1979–2022, the fluctuation of longwave radiation is greater than that of shortwave radiation. The seasonal variation of shortwave radiation is obvious, while that of longwave radiation is small. The increasing trend of longwave radiation may result from global warming, in which ice sheets absorb more solar radiation and the surface heats up significantly, emitting more LWU.