Ice crystal numbers in Arctic clouds over sea ice and ocean: satellite retrievals and cloud-resolving modelling

Mixed-phase and ice clouds are prominent parts of the Arctic climate system. In particular, boundary layer clouds and their interactions with local aerosols may play an important role in the amplified warming that has been observed in the Arctic during the recent years. These aerosols which are known as ice nucleating particles (INPs) are necessary for the heterogeneous ice formation in temperatures above -38^oC. Several in-situ observations have measured a high number of effective ice nucleating particles, possibly related to biological activity in the open ocean. In contrast, in our previous study analyzing the novel active remote sensing dataset DARDAR-Nice for ten years in the Arctic region (Papakonstantinou-Presvelou et al., 2022), we found an increased ice number in low-level clouds over sea ice compared to the open ocean, suggesting other possible factors that might contribute to this difference. Here we perform several sensitivity experiments with the ICON model at kilometer-scale resolution in order to investigate the effect of these factors to the ice number, namely the contribution of local INPs, blowing snow and secondary ice production.