Improved simulation of the polar atmospheric boundary layer by accounting for aerodynamic roughness in the parameterisation of surface scalar exchange over sea ice

Elvidge, Andrew D. ORCID: https://orcid.org/0000-0002-7099-902X, Renfrew, Ian A. ORCID: https://orcid.org/0000-0001-9379-8215, Edwards, John M., Brooks, Ian M., Srivastava, Piyush and Weiss, Alexandra I. (2023) Improved simulation of the polar atmospheric boundary layer by accounting for aerodynamic roughness in the parameterisation of surface scalar exchange over sea ice. Journal of Advances in Modeling Earth Systems, 15 (3). ISSN 1942-2466

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Abstract

A new, simple parameterisation 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 challenge for modelling polar weather and climate.

Item Type: Article
Additional Information: Research Funding: NERC Grant Numbers: NE/S000453/1, NE/S000690/1, NE/I028297/1, NE/N009754/1. Data Availability Statement: This study uses aircraft-based observations from the ACCACIA and IGP field campaigns. These observations are available at CEDA via British Antarctic Survey (2014) for the ACCACIA data set, and via Renfrew (2019) for the IGP data set. The study also comprises of model simulations in the Met Office Unified Model (MetUM). For reproducibility, Section 2.1 describes in detail the baseline MetUM configuration used for these simulations, whilst Section 2.4 describes in detail the sea ice surface exchange parameterisation settings used in each individual simulation. The simulations were carried out on the MONSooN supercomputer. MONSooN is a collaborative facility supplied under the Joint Weather and Climate Research Programme, a strategic partnership between the Met Office and NERC.
Uncontrolled Keywords: sdg 13 - climate action ,/dk/atira/pure/sustainabledevelopmentgoals/climate_action
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: LivePure Connector
Date Deposited: 16 Jan 2023 17:31
Last Modified: 22 Mar 2023 10:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/90598
DOI: 10.1029/2022MS003305

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