Observations of surface momentum exchange over the marginal ice zone and recommendations for its parametrisation

Elvidge, Andrew ORCID: https://orcid.org/0000-0002-7099-902X, Renfrew, Ian ORCID: https://orcid.org/0000-0001-9379-8215, Weiss, A. I., Brooks, I. M., Lachlan-Cope, T. A. and King, J. C. (2016) Observations of surface momentum exchange over the marginal ice zone and recommendations for its parametrisation. Atmospheric Chemistry and Physics, 16. pp. 1545-1563. ISSN 1680-7324

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Abstract

Comprehensive aircraft observations are used to characterise surface roughness over the Arctic marginal ice zone (MIZ) and consequently make recommendations for the parametrisation of surface momentum exchange in the MIZ. These observations were gathered in the Barents Sea and Fram Strait from two aircraft as part of the Aerosol–Cloud Coupling And Climate Interactions in the Arctic (ACCACIA) project. They represent a doubling of the total number of such aircraft observations currently available over the Arctic MIZ. The eddy covariance method is used to derive estimates of the 10 m neutral drag coefficient (CDN10) from turbulent wind velocity measurements, and a novel method using albedo and surface temperature is employed to derive ice fraction. Peak surface roughness is found at ice fractions in the range 0.6 to 0.8 (with a mean interquartile range in CDN10 of 1.25 to 2.85  ×  10−3). CDN10 as a function of ice fraction is found to be well approximated by the negatively skewed distribution provided by a leading parametrisation scheme (Lüpkes et al., 2012) tailored for sea-ice drag over the MIZ in which the two constituent components of drag – skin and form drag – are separately quantified. Current parametrisation schemes used in the weather and climate models are compared with our results and the majority are found to be physically unjustified and unrepresentative. The Lüpkes et al. (2012) scheme is recommended in a computationally simple form, with adjusted parameter settings. A good agreement holds for subsets of the data from different locations, despite differences in sea-ice conditions. Ice conditions in the Barents Sea, characterised by small, unconsolidated ice floes, are found to be associated with higher CDN10 values – especially at the higher ice fractions – than those of Fram Strait, where typically larger, smoother floes are observed. Consequently, the important influence of sea-ice morphology and floe size on surface roughness is recognised, and improvement in the representation of this in parametrisation schemes is suggested for future study.

Item Type:	Article
Uncontrolled Keywords:	sdg 13 - climate action ,/dk/atira/pure/sustainabledevelopmentgoals/climate_action
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 > Marine and Atmospheric Sciences (former - to 2017) Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences Faculty of Science > Research Groups > Meteorology, Oceanography and Climate Dynamics (former - to 2017) Faculty of Science > Research Groups > Climate, Ocean and Atmospheric Sciences (former - to 2017)
Depositing User:	Pure Connector
Date Deposited:	02 Mar 2016 12:00
Last Modified:	20 Mar 2023 10:41
URI:	https://ueaeprints.uea.ac.uk/id/eprint/57356
DOI:	10.5194/acp-16-1545-2016

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