Greenland Ice Sheet Memory for Cloud Radiation determines its impact on the Surface Mass Balance

As of yet, there is no consensus on the role of the cloud radiative effect (CRE) on the Greenland Ice Sheet (GrIS). This study focuses on the seasonal and temporal variability of the CRE, to better understand the response of the firn. To do so, we combine satellite observations, climate-model output, and a snow model. We separate short-term and long-term impacts. The results show a positive CRE for all seasons, with an annual short-term CRE of 24.7 $Wm^{-2}$, which is largest in fall. The long-term response of the GrIS to the CRE is positive and dominant in summer ablation areas, decreasing the albedo and enhancing melt-water runoff. This long-term effect stresses the influence of the firn conditions on its response to CRE, and highlights the need to include a snow model to study GrIS cloud radiation. The (lack off) long-term component of the CRE explains the conflict in previous studies.