Submesoscale eddies and sea ice interaction&#8239;
Authors: Greig Lily , Ferreira David 
Published: March 2022

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&lt;p&gt;&lt;span&gt;The submesoscale has been defined dynamically as those processes with Rossby and Richardson numbers approaching O(1). This scale is of emerging interest within oceanography due to the role it plays in surface layer nutrient and tracer transport. Submesoscale baroclinic eddies or mixed layer eddies (MLEs), if energise&lt;/span&gt;&lt;span&gt;d&lt;/span&gt;&lt;span&gt;&amp;#160;in&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;the m&lt;/span&gt;&lt;span&gt;arginal ice zone (MIZ),&amp;#160;have the potential to impact both the rate of ice melt/formation and the magnitude of air-sea heat fluxes in the vicinity of the ice edge.&lt;/span&gt;&lt;span&gt;&amp;#8239;&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt;
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&lt;p&gt;&lt;span&gt;In this study, an MITgcm idealised high resolution simulation is used to quantify the impact of MLEs in the vicinity of the ice edge, focusing on the thermodynamic component. The domain (75 km by 75 km at 250&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;m resolution) is a zonally re-entrant channel with ice-free/ice-covered conditions in the South/North, representing a lead or the MIZ. To measure the eddy impact on both sea ice and air-sea heat fluxes, comparisons are made between a 3D simulation with eddies and a 2D simulation with no eddies (no zonal extension, but otherwise identical to the 3D version).&amp;#8239;Typical conditions (stratification, forcing) of the Arctic/Antarctic and summer/winter seasons are considered.&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt;
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&lt;p&gt;&lt;span&gt;When eddies are permitted to&amp;#160;energize&amp;#160;and develop within these&amp;#160;simulations, their&amp;#160;impacts are numerous and coupled:&amp;#160;under summer Artic conditions,&amp;#160;meridional&amp;#160;heat&amp;#160;transport&amp;#160;to the ice-covered region&amp;#160;is tripled with eddies&amp;#160;present, which leads to a first order impact on the sea ice melt&amp;#160;and&amp;#160;a doubling of the&amp;#160;average&amp;#160;heat storage in the ice-covered ocean.&amp;#160;Novel analysis into the direct impact of these eddies on air-sea heat fluxes&amp;#160;also&amp;#160;shows that&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;- due&amp;#160;the&amp;#160;partial absorption of&amp;#160;downwelling&amp;#160;solar&amp;#160;radiation&amp;#160;by sea ice&amp;#160;cover&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;-&amp;#160;the&amp;#160;solar&amp;#160;heat flux&amp;#160;into&amp;#160;the ice-covered&amp;#160;mixed layer&amp;#160;increases by 20%&amp;#160;when eddies are present.&amp;#160;Computing&amp;#160;the residual overturning&amp;#160;stream&amp;#160;function,&amp;#160;responsible for&amp;#160;driving warmer&amp;#160;waters under the ice,&amp;#160;reveals&amp;#160;the ocean&amp;#160;dynamics&amp;#160;behind these impacts.&amp;#160;The&amp;#160;overturning,&amp;#160;weakly present in the 2D model due to&amp;#160;frontogenesis, increases threefold in the 3D case with&amp;#160;submesoscale&amp;#160;eddies.&amp;#160;Tests with the Fox-Kemper parameterization within the 2D set-up are also helping evaluate to which extent this parameterization can capture the influence of MLE eddies in these polar conditions.&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt;
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