Abstract
The heterogeneity of sea ice in the marginal ice zone (MIZ) causes
multiscale secondary circulations that are challenging to model or
observe. Their absent or inadequate representation in ocean-atmosphere
interactions in climate models is partially responsible for the
underestimation of Arctic sea ice loss. Observationally, such
circulations obfuscate the interpretation of polar atmospheric chemistry
measurements, among others. To address this open challenge, large-eddy
simulations are conducted over real-world satellite-sensed sea ice maps,
and idealizations of these maps that alter the ice pattern but conserve
its fraction, showing that the ice fraction of a surface is not
sufficient to predict surface heat flux. In a second suite of
simulations, three other heterogeneity metrics (representing the surface
fragmentation, tortuosity, and patch size variability) are then
introduced; varying them among simulations suggests that surface-air
interactions will be significantly impacted. Based on these results, we
then show, using a multi-linear regression of map features, that MIZ
surface parameterizations in Earth Systems Models can be improved if
they account for these various features of the surface. Finally, the
simulations also illustrate that the contribution of roughness changes
to the resulting atmospheric circulations are minimal compared to
thermal heterogeneity in the MIZ.