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Impact of sea-ice model complexity on the performance of an unstructured-mesh sea-ice/ocean model under different atmospheric forcings
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  • Lorenzo Zampieri,
  • Frank Kauker,
  • Jörg Fröhle,
  • Hiroshi Sumata,
  • Elizabeth C Hunke,
  • Helge Goessling
Lorenzo Zampieri
Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research

Corresponding Author:[email protected]

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Frank Kauker
Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research
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Jörg Fröhle
Kiel University
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Hiroshi Sumata
Norwegian Polar Insitite, Fram Centre
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Elizabeth C Hunke
Los Alamos National Laboratory
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Helge Goessling
Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research
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We have equipped the unstructured-mesh global sea-ice and ocean model FESOM2 with a set of physical parameterizations derived from the single-column sea-ice model Icepack. The update has substantially broadened the range of physical processes that can be represented by the model. The new features are directly implemented on the unstructured FESOM2 mesh, and thereby benefit from the flexibility that comes with it in terms of spatial resolution. A subset of the parameter space of three model configurations, with increasing complexity, has been calibrated with an iterative Green’s function optimization method to test fairly the impact of the model update on the sea-ice representation. Furthermore, to explore the sensitivity of the results to different atmospheric forcings, each model configuration was calibrated separately for the NCEP-CFSR/CFSv2 and ERA5 forcings. The results suggest that a complex model formulation leads to a better agreement between modeled and the observed sea-ice concentration and snow thickness, while differences are smaller for sea-ice thickness and drift speed. However, the choice of the atmospheric forcing also impacts the agreement of FESOM2 simulations and observations, with NCEP-CFSR/CFSv2 being particularly beneficial for the simulated sea-ice concentration and ERA5 for sea-ice drift speed. In this respect, our results indicate that the parameter calibration can better compensate for differences among atmospheric forcings in a simpler model (i.e. sea-ice has no heat capacity) than in more energy consistent formulations with a prognostic ice thickness distribution.
May 2021Published in Journal of Advances in Modeling Earth Systems volume 13 issue 5. 10.1029/2020MS002438