Scale Dependent Parametrisation of Processes in the Atmospheric Boundary Layer over Arctic Sea Ice

The general goal of SPARCS consists in a study of the consequences of a reduced arctic sea ice concentration on the turbulent processes in the lowest one kilometer (boundary layer) of the atmosphere over the Arctic Ocean.

Atmospheric boundary layer processes over sea ice cannot be modeled in large detail by the present climate models which is due to their low spatial resolution compared with the typical scale of near-surface atmospheric processes and their small-scale variability, especially over fractional sea ice cover. So, the present project aims to overcome this gap by improving physical descriptions (parametrisations) of atmospheric boundary layer turbulence over regions with non-homogeneous sea ice distribution. The main focus will be on the effect of openings in sea ice on the exchange of energy and momentum between ocean, sea ice and atmosphere. Such openings develop due to non-homogeneous sea ice drift (leads) (see Figure 1.) and due to melting (ponds). The new parametrisations  of turbulent processes over non-homogeneous sea ice cover will be developed for atmospheric models with different resolutions and will finally be made available for the MiKlip prediction system ECHAM6/MPIOM.

With this goal the project SPARCS helps to incorporate those processes in climate models that are important for a realistic representation of decadal climate variability. SPARCS uses data of two decades from ship and aircraft campaigns as well as from remote sensing to investigate the impact of the changed sea ice cover on characteristics of the polar atmospheric boundary layer. This helps to achieve a better understanding of the decadal variability of arctic climate processes.