What determines the Arctic solar radiation energy budget at the surface most strongly: Clouds, surface albedo, or the solar zenith angle?

Cloud total water path (TWP), surface albedo ( α ), and solar zenith angle (SZA) are the main parameters driving the solar radiative energy budget (REB) at the surface in the Arctic. We have used results of simulations with a coupled Arctic regional climate model to quantify the spatio-temporal sensitivity of the solar REB at the surface with respect to changes of these three parameters. The simulations covered the period of polar day during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in 2020. Two methods have been employed to quantify the relative impact of the variability of the three parameters: a standardized regression method and a machine learning algorithm. Both approaches provided similar sensitivities of the solar REB at the surface with respect to cloud TWP, α , and SZA. Averaged over the period from April to September 2020, the SZA appeared as the most important factor determining changes of the solar REB at the surface. However, its relative influence exhibited the lowest spatial variability over the Arctic area as compared to the relative impact of cloud TWP and α . In spring, after the onset of melting, when the cloud TWP was still relatively low, the relative effect of surface albedo variability dominated the changes of the solar REB at the surface. The situation reversed in summer, when cloud TWP increased and α decreased due to sea ice melt. For values of TWP < 70 g m −2 , and α > 0.4, the relative impact of the cloud TWP on changes of the solar REB at the surface was generally smaller than that of the surface albedo. • The impact of cloud water path, surface albedo, and solar zenith angle on the net irradiance in the Arctic was quantified. • On a seasonal average, the solar zenith angle appeared as the most important parameter with the lowest spatial variability. • The relative impact of cloud total water path (TWP) exceeded that of surface albedo ( α ) for TWP > 70 g m −2 and α < 0 . 4 .