Simulations of two Arctic winter cloud regimes

Abstract:

Recent analysis of observations from the Surface Heat Budget Experiment (SHEBA) provides evidence that in winter the Arctic exhibits two preferred and persistent states — a radiatively clear and a radiatively opaque state. These distinct regimes are influenced by the phase of the clouds, and affect the surface radiative fluxes. We explore the radiative and microphysical effects of these Arctic clouds in two present-day climate simulations. We compare simulations performed with a global coupled ocean– atmosphere model [the Community Earth System Model], and its superparameterized counterpart (SP-CESM). We find that the SP-CESM is able to better reproduce both of the preferred winter states, compared to CESM. We present an analysis of the mechanisms and processes behind these findings.