Uncertainties of drag coefficient estimates above sea ice from field data

Blein, Sébastien, Guemas, Virginie, Brooks, Ian M., Elvidge, Andrew D. ORCID: https://orcid.org/0000-0002-7099-902X and Renfrew, Ian A. ORCID: https://orcid.org/0000-0001-9379-8215 (2024) Uncertainties of drag coefficient estimates above sea ice from field data. Boundary-Layer Meteorology, 190 (2). ISSN 0006-8314

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Abstract

Surface turbulent exchanges play a key role on sea ice dynamics, on ocean and sea ice heat budgets and on the polar atmosphere. Uncertainties in parameterizations of surface turbulent fluxes are mostly held by the transfer coefficients and estimates of those transfer coefficients from field data are required for parameterization development. Measurement errors propagate through the computation of transfer coefficients and contribute to its total error together with the uncertainties in the empirical stability functions used to correct for stability effects. Here we propose a methodology to assess their contributions individually to each coefficient estimate as well as the total drag coefficient uncertainty and we apply this methodology on the example of the SHEBA campaign. We conclude that for most common drag coefficient values (between 1.0×10 -3 and 2.5×10 -3), the relative total uncertainty ranges from 25 and 50%. For stable or unstable conditions with a stability parameter |ζ|>1 on average, the total uncertainty in the neutral drag coefficient exceeds the neutral drag coefficient value itself, while for |ζ|<1 the total uncertainty is around 25% of the drag coefficient. For closer-to-neutral conditions, this uncertainty is dominated by measurement uncertainties in surface turbulent momentum fluxes which should therefore be the target of efforts in uncertainty reduction. We also propose an objective data-screening procedure for field data, which consists of retaining data for which the relative error on neutral drag coefficient does not exceed a given threshold. This method, in addition to the commonly used flux quality control procedure, allows for a reduction of the drag coefficient dispersion compared to other data-screening methods, which we take as an indication of better dataset quality.

Item Type: Article
Additional Information: Funding Information: This work was supported by a national funding by the Agence Nationale de la Recherche within the framework of the Investissement d’Avenir program under the ANR-17-MPGA-0003 reference. This article has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101003826 via project CRiceS (Climate Relevant interactions and feedbacks: the key role of sea ice and Snow in the polar and global climate system).
Uncontrolled Keywords: bulk parameterizations,polar regions,transfer coefficient uncertainties,turbulent surface fluxes,atmospheric science,2* ,/dk/atira/pure/subjectarea/asjc/1900/1902
Faculty \ School: Faculty of Science > School of Environmental Sciences
University of East Anglia Research Groups/Centres > Theme - ClimateUEA
UEA Research Groups: Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
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Depositing User: LivePure Connector
Date Deposited: 26 Mar 2024 09:30
Last Modified: 03 Apr 2024 09:31
URI: https://ueaeprints.uea.ac.uk/id/eprint/94754
DOI: 10.1007/s10546-023-00851-9

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