In this study we focus on the relative importance of different background aerosol concentrations on MPC formation and persistence in the Arctic. Motivated by current Arctic sea ice retreat, we additionally contrast the simulated MPC over open ocean versus sea ice surfaces. To address this, we perform high resolution COSMO-LES simulations on 20x20 km2 domains based on the Aerosol-Cloud Coupling and Climate Interactions in the Arctic (ACCACIA) campaign carried out in March 2013 in the European Arctic. In our setup we successfully simulate a realistic MPC as compared to observations.
We find that changes in surface conditions impact cloud dynamics considerably: MPCs over sea ice are rather homogeneous. In contrast, MPCs over the ocean display organized structures of shallow convection with high spatial variability and increased precipitation formation in the updraft cores.
To additionally investigate the effect of aerosol loadings on Arctic MPC properties, we performed several sensitivity studies, resembling pollution advected from the mid latitudes (known as Arctic haze in spring). Our simulations suggest that aerosols significantly affect the liquid and ice phase of MPCs. Smaller aerosol loadings are needed over sea ice than over the ocean to shift the cloud properties beyond the background state. To further address the robustness of our results, we apply different perturbations across a +-2K temperature range.