Improved Simulation of the Polar Atmospheric Boundary Layer by Accounting for Aerodynamic Roughness in the Parameterization of Surface Scalar Exchange Over Sea Ice

Elvidge, A.D.; Renfrew, I.A.; Edwards, J.M.; Brooks, I.M.; Srivastava, P.; Weiss, A.I.. 2023 Improved Simulation of the Polar Atmospheric Boundary Layer by Accounting for Aerodynamic Roughness in the Parameterization of Surface Scalar Exchange Over Sea Ice. Journal of Advances in Modeling Earth Systems, 15 (3), e2022MS003305. 20, pp. https://doi.org/10.1029/2022MS003305

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Text (Open Access) © 2023 The Authors. Journal of Advances in Modeling Earth Systems published by Wiley Periodicals LLC on behalf of American Geophysical Union. J Adv Model Earth Syst - 2023 - Elvidge - Improved Simulation of the Polar Atmospheric Boundary Layer by Accounting for.pdf - Published Version Available under License Creative Commons Attribution 4.0. Download (4MB) | Preview

Abstract/Summary

A new, simple parameterization scheme for scalar (heat and moisture) exchange over sea ice and the marginal ice zone is tested in a numerical weather and climate prediction model. This new “Blended A87” scheme accounts for the influence of aerodynamic roughness on the relationship between momentum and scalar exchange over consolidated sea ice, in line with long-standing theory and recent field observations, and in contrast to the crude schemes currently operational in most models. Using aircraft observations and Met Office Unified Model simulations of cold-air outbreak (CAO) conditions over aerodynamically rough sea ice, we demonstrate striking improvements in model performance when the Blended A87 scheme replaces the model's operational treatment for surface scalar exchange, provided that the aerodynamic roughness over consolidated ice is appropriately prescribed. The mean biases in surface sensible heat flux, surface latent heat flux, near-surface air temperature, and surface temperature reduce from 25 to 11 W m−2, 22 to 12 W m−2, 0.8 to 0.0 K, and 1.4 to 0.8 K, respectively. We demonstrate that such impacts on surface exchange over sea ice can have a marked impact on the evolution of the atmospheric boundary layer across hundreds of kilometres downwind of the sea ice during CAO conditions in the model. Our results highlight the importance of spatiotemporal variability in the topography of consolidated sea ice for both momentum and scalar exchange over sea ice; accounting for which remains a key challenge for modeling polar weather and climate.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1029/2022MS003305
ISSN:	1942-2466
Additional Keywords:	surface exchange parameterization, turbulent fluxes, sea ice, air-sea-ice interaction, atmospheric boundary layer, polar climate
Date made live:	09 Mar 2023 11:42 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/534190

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