#24 Topic: Polar boundary layer turbulence and its parametrization
Lecturer: Christof Lüpkes
Date: Monday, January 9, 2023 10:00 – 11:00 a.m.

The interaction between the polar atmosphere, ocean and sea ice is governed by radiation and atmospheric turbulence, causing fluxes of energy and momentum. The turbulent transport processes occur in the atmospheric boundary layer, which shows some specific features in polar regions. The first part of this talk concentrates on the explanation of these polar boundary layer characteristics with a focus on turbulent processes in different flow regimes. Further, examples of turbulence parametrizations are explained that have been developed mainly at AWI in the last decades and have been used partly also in (AC)³. A focus is here on nonlocal turbulence closures and their advantages to local closures in different flow regimes and on different scales. The final part of the talk is related to surface layer parametrizations over fractional sea ice. The principal of these parametrizations is explained starting with the parametrization of the neutral drag coefficient and ending with its stability dependence over inhomogenous sea ice cover. Examples of the effect of these parametrizations for prescribed sea ice cover are discussed for Arctic and Antarctic conditions.