Spatial-temporal variation of surface radiation budget over the Arctic sea ice region from 1981 to 2020

Objectives: The surface net radiation and cloud radiative forcing are of great importance to understand global climate and environmental changes, which change significantly with the rapidly decline of sea ice in the Arctic. Methods: A long-term dataset of 40 years (1981-2020) from the ERA5 reanalysis data is adopted to investigate the seasonal, annual and decadal variations in surface net shortwave radiation, surface net longwave radiation, surface net all-wave radiation, shortwave cloud radiative forcing, longwave cloud radiation forcing, and all-wave cloud radiative forcing. Results: The results showed that the surface net all-wave radiation exhibited a warming effect in summer over the Arctic sea ice region from 1981-2020 and the average was 84.16 W m^-2. In contrast, the all-wave cloud radiative forcing caused -16.78 W m^-2 of cooling in summer. Conclusions: Shortwave radiation contributes most to the surface net radiation and cloud radiative forcing. The shortwave net radiation showed a significant increasing trend from 1981 to 2020 with 2.22 W m^-2 decade^-1, while declined at a speed of -6.58 W m^-2 decade^-1 in 2011-2020. The summer average of shortwave cloud radiative forcing was -67.91 W m^-2, and it decreased deeply by -2.75 W m^-2 decade^-1, indicating that the cooling effect of cloud on the surface was enhanced. The spatial distribution of summer trends showed that the highest changing rate of surface radiation fluxes existed in the Arctic marginal sea area, especially in the Barents-Kara Sea, where the surface net all-wave radiation and all-wave cloud radiation forcing changed fastest in summer.