Boundary-Layer Processes over Sea Ice in Observations and Modeled with an Atmospheric-Ocean Single-Column Model (AOSCM)

Gunilla Svensson, Stockholm Univ., Stockholm, Sweden; and K. Hartung, J. I. Holt, M. Tjernstrom, M. Karalis, A. Lewinschal, and H. Struthers
[12-Jan-2023] Abstract  The polar regions are known for their complex small-scale processes that need to be parameterised in models, such as the formation of clouds, boundary-layer mixing in ocean and atmosphere, sea ice formation/melt and the surface energy exchanges. These processes are also involved in substantial feedback mechanisms in the climate system. Numerical models, for weather forecasts and climate applications, have been shown to have large biases in polar regions that may originate from these parameterised processes. The Atmosphere-Ocean Single-Column Model (AOSCM) is a recently developed tool which here is applied at locations in the Arctic where detailed observations taken during expeditions with the Swedish icebreaker Oden and also the ongoing year-long MOSAiC expedition. The AOSCM extends from the ocean bottom, through the sea ice and snow, to the top-of-atmosphere. Here, the model is used in combination with observations to understand sensitivities to representation of boundary-layer processes and low-level clouds for various conditions and its importance for the surface energy budget.