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Simple hybrid sea ice nudging method for improving control over partitioning of sea ice concentration and thickness
  • Alexandre Audette,
  • Paul J. Kushner
Alexandre Audette
University of Toronto

Corresponding Author:[email protected]

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Paul J. Kushner
University of Toronto
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Abstract

To assess the effect of ocean-atmosphere coupling in the climate response to forced sea ice loss, the PAMIP (Polar Amplification Model Intercomparison Project) protocol includes centennial coupled atmosphere-ocean general circulation model simulations with imposed sea ice loss. The protocol, which specifies sea ice concentration and thickness distribution targets, does not prescribe a method for achieving them. Although different methods for imposing sea ice loss (or growth) in models have been documented, testing of the method-dependence of the resulting climate responses has been limited. Achieving the targeted sea ice state has proven to be challenging using the ghost-flux nudging method, which induces ice melt from below, as this method does not constrain the partitioning between thickness and concentration. We propose, describe and test a Simple method that combines the advantages of direct sea ice nudging and ghost-flux nudging. This hybrid nudging method is able to better capture the partitioning between thickness and concentration while conserving total water content. We document thoroughly the ability of this novel sea ice constraining method to reach specific targets for both polar regions.