Sensitivity to changes in the surface‐layer turbulence parameterization for stable conditions in winter: A case study with a regional climate model over the Arctic

• Published in: Atmospheric Science Letters
• Main Authors: Schneider, Thea, Lüpkes, Christof, Dorn, Wolfgang, Chechin, Dmitry, Handorf, Dörthe, Khosravi, Sara, Gryanik, Vladimir M., Makhotina, Irina, Rinke, Annette, Schneider, Thea; 1 Institute of Physics and Astronomy University of Potsdam Potsdam Germany, Lüpkes, Christof; 2 Helmholtz Centre for Polar and Marine Research Alfred Wegener Institute Bremerhaven Germany, Dorn, Wolfgang; 3 Helmholtz Centre for Polar and Marine Research Alfred Wegener Institute Potsdam Germany, Chechin, Dmitry; 4 A.M. Obukhov Institute of Atmospheric Physics RAS Moscow Russia, Handorf, Dörthe; 3 Helmholtz Centre for Polar and Marine Research Alfred Wegener Institute Potsdam Germany, Khosravi, Sara; 3 Helmholtz Centre for Polar and Marine Research Alfred Wegener Institute Potsdam Germany, Gryanik, Vladimir M.; 2 Helmholtz Centre for Polar and Marine Research Alfred Wegener Institute Bremerhaven Germany, Makhotina, Irina; 5 Atmosphere‐Ocean Interaction Department Arctic and Antarctic Research Institute St.‐Petersburg Russia
• Format: Article in Journal/Newspaper
• Language: English
• Published: John Wiley & Sons, Ltd. 2021
• Subjects: ddc:551.5; Arctic; atmospheric boundary layer; regional climate modeling; Arctic Ocean; Sea ice; Surface Heat Budget of the Arctic Ocean
• Online Access: https://doi.org/10.1002/asl.1066; http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/9742

The modeling of the atmospheric boundary layer over sea ice is still challenging because of the complex interaction between clouds, radiation and turbulence over the often inhomogeneous sea ice cover. There is still much uncertainty concerning sea ice roughness, near‐surface thermal stability and related processes, and their accurate parameterization. Here, a regional Arctic climate model forced by ERA‐Interim data was used to test the sensitivity of climate simulations to a modified surface flux parameterization for wintertime conditions over the Arctic. The reference parameterization as well as the modified one is based on Monin–Obukhov similarity theory, but different roughness lengths were prescribed and the stability dependence of the transfer coefficients for momentum, heat and moisture differed from each other. The modified parameterization accounts for the most comprehensive observations that are presently available over sea ice in the inner Arctic. Independent of the parameterization used, the model was able to reproduce the two observed dominant winter states with respect to cloud cover and longwave radiation. A stepwise use of the different parameterization assumptions showed that modifications of both surface roughness and stability dependence had a considerable impact on quantities such as air pressure, wind and near‐surface turbulent fluxes. However, the reduction of surface roughness to values agreeing with those observed during the Surface Heat Budget of the Arctic Ocean campaign led to an improvement in the western Arctic, while the modified stability parameterization had only a minor impact. The latter could be traced back to the model's underestimation of the strength of stability over sea ice. Future work should concentrate on possible reasons for this underestimation and on the question of generality of the results for other climate models. The modeling of the atmospheric boundary layer over sea ice is challenging. This is, among others, due to the distinct sea ice surface roughness and ...