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Large Eddy Simulations of the Atmospheric Boundary Layer Over Satellite‐Sensed Sea Ice Maps.

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Title: Large Eddy Simulations of the Atmospheric Boundary Layer Over Satellite‐Sensed Sea Ice Maps.
Authors: Fogarty, Joseph1 (AUTHOR), Bushuk, Mitchell2 (AUTHOR), Calaf, Marc3 (AUTHOR), Allouche, Mohammad1,4 (AUTHOR), Ghannam, Khaled5 (AUTHOR), Bou‐Zeid, Elie1 (AUTHOR) ebouzeid@princeton.edu
Source: Journal of Geophysical Research. Atmospheres. 6/16/2026, Vol. 131 Issue 11, p1-24. 24p.
Subject Terms: *Sea ice, *Ocean-atmosphere interaction, Atmospheric boundary layer, Surface properties, Large eddy simulation models, Satellite-based remote sensing, Atmospheric models
Geographic Terms: Arctic regions
Abstract: Surface heterogeneity in the marginal ice zone (MIZ) causes multiscale secondary atmospheric circulations that are challenging to model or observe. The absence or inadequate representation of these circulations in ocean‐atmosphere exchange schemes in climate models is partially responsible for the underestimation of Arctic sea ice loss. Observationally, such circulations obfuscate the interpretation of polar atmospheric chemistry measurements, among others. To address this open challenge, large‐eddy simulations are conducted over real‐world satellite‐sensed sea ice maps with an ice‐sea temperature contrast, as well as over idealizations of these maps that alter the ice pattern but conserve its fraction, showing that the ice fraction of a surface is not sufficient to predict the surface heat flux. In a second suite of simulations, three other heterogeneity metrics (representing the surface fragmentation, patch edge tortuosity, and patch size variability) are introduced to complement the ice fraction in describing the surface. Simulations varying these parameters suggest that they also significantly impact surface‐air interactions. A roughness contrast is then added to the surface temperature contrast, indicating that the contribution of roughness changes to the resulting atmospheric circulations is less pronounced than that of thermal heterogeneity. Based on these results, we illustrate, using a multi‐linear regression on these map features, that MIZ surface parameterizations in Earth Systems Models can be improved if they account for these various characteristics of the sea‐ice patterns. Plain Language Summary: This study investigates how the complex horizontal structure of sea ice affects surface‐atmosphere interactions in the Arctic. The irregularities and variability in sea ice shape and distribution create intricate patterns, giving rise to atmospheric dynamics that are difficult for climate models to simulate accurately. Numerical simulations were conducted of air flow in the atmospheric boundary layer overlying realistic sea ice patterns obtained from satellites, and simplified versions of these patterns. The simulations over the simplified patterns showed that merely knowing the ice fraction is insufficient for predicting heat exchange at the surface. The simulations over the real‐world patterns were then used to analyze how other measures of ice heterogeneity, such as fragmentation, tortuosity, and patch size variability, affected the resulting atmospheric dynamics. Moreover, the impact on atmospheric circulation of changes in the surface roughness between water and ice is shown to be minor compared to the effects of the surface temperature difference between the two surfaces. The findings suggest that incorporating these varied surface features into Earth Systems Models can enhance the accuracy of surface parameterizations and climate projections. Key Points: Exchanges of momentum and heat between the atmosphere and marginal ice zone result from a combination of turbulent and dispersive transportThe surface ice fraction is necessary but not sufficient to accurately predict surface atmosphere exchangesWind direction, patch size and its variability, and the tortuosity of the water‐ice interface can improve air‐sea fluxes parameterizations [ABSTRACT FROM AUTHOR]
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Description
Abstract:Surface heterogeneity in the marginal ice zone (MIZ) causes multiscale secondary atmospheric circulations that are challenging to model or observe. The absence or inadequate representation of these circulations in ocean‐atmosphere exchange schemes in climate models is partially responsible for the underestimation of Arctic sea ice loss. Observationally, such circulations obfuscate the interpretation of polar atmospheric chemistry measurements, among others. To address this open challenge, large‐eddy simulations are conducted over real‐world satellite‐sensed sea ice maps with an ice‐sea temperature contrast, as well as over idealizations of these maps that alter the ice pattern but conserve its fraction, showing that the ice fraction of a surface is not sufficient to predict the surface heat flux. In a second suite of simulations, three other heterogeneity metrics (representing the surface fragmentation, patch edge tortuosity, and patch size variability) are introduced to complement the ice fraction in describing the surface. Simulations varying these parameters suggest that they also significantly impact surface‐air interactions. A roughness contrast is then added to the surface temperature contrast, indicating that the contribution of roughness changes to the resulting atmospheric circulations is less pronounced than that of thermal heterogeneity. Based on these results, we illustrate, using a multi‐linear regression on these map features, that MIZ surface parameterizations in Earth Systems Models can be improved if they account for these various characteristics of the sea‐ice patterns. Plain Language Summary: This study investigates how the complex horizontal structure of sea ice affects surface‐atmosphere interactions in the Arctic. The irregularities and variability in sea ice shape and distribution create intricate patterns, giving rise to atmospheric dynamics that are difficult for climate models to simulate accurately. Numerical simulations were conducted of air flow in the atmospheric boundary layer overlying realistic sea ice patterns obtained from satellites, and simplified versions of these patterns. The simulations over the simplified patterns showed that merely knowing the ice fraction is insufficient for predicting heat exchange at the surface. The simulations over the real‐world patterns were then used to analyze how other measures of ice heterogeneity, such as fragmentation, tortuosity, and patch size variability, affected the resulting atmospheric dynamics. Moreover, the impact on atmospheric circulation of changes in the surface roughness between water and ice is shown to be minor compared to the effects of the surface temperature difference between the two surfaces. The findings suggest that incorporating these varied surface features into Earth Systems Models can enhance the accuracy of surface parameterizations and climate projections. Key Points: Exchanges of momentum and heat between the atmosphere and marginal ice zone result from a combination of turbulent and dispersive transportThe surface ice fraction is necessary but not sufficient to accurately predict surface atmosphere exchangesWind direction, patch size and its variability, and the tortuosity of the water‐ice interface can improve air‐sea fluxes parameterizations [ABSTRACT FROM AUTHOR]
ISSN:2169897X
DOI:10.1029/2024JD042062