Preprints
https://doi.org/10.5194/tc-2022-110
https://doi.org/10.5194/tc-2022-110
07 Jun 2022
 | 07 Jun 2022
Status: this preprint is currently under review for the journal TC.

Impact of atmospheric forcing uncertainties on Arctic and Antarctic sea ice simulation in CMIP6 OMIP

Xia Lin, François Massonnet, Thierry Fichefet, and Martin Vancoppenolle

Abstract. Atmospheric reanalyses are valuable datasets to drive ocean-sea ice general circulation model and to propose multi-decadal reconstructions of the ocean-sea ice system in polar regions. However, these reanalyses exhibit biases in these regions. It was previously found that the representation of Arctic and Antarctic sea ice in models participating in the Ocean Model Intercomparison Project Phase 2 (OMIP2, using the Japanese 55-year atmospheric reanalysis) was significantly more realistic than in the OMIP1 (forced by atmospheric state from the Coordinated Ocean-ice Reference Experiments version 2, CORE-II). To understand why, we study the sea ice concentration budget and its relations to surface heat and momentum fluxes, as well as the connections between the simulated ice drift and the ice concentration, the ice thickness and the wind stress in a subset of three models (CMCC-CM2-SR5, MRI-ESM2-0, and NorESM2-LM). These three models are representative of the ensemble and are the only ones to provide the tendencies of ice concentration attributed to dynamic and thermodynamic processes required for the ice concentration budget analysis. It is found that negative summer biases in high-ice concentration regions and positive biases in the Canadian Arctic Archipelago (CAA) and central Weddell Sea (CWS) regions are reduced from OMIP1 to OMIP2 due to surface heat fluxes changes. Net shortwave radiation fluxes provide key improvements in the Arctic interior, CAA and CWS regions. There is also an influence of improved surface wind stress in OMIP2 giving better winter Antarctic ice concentration and the Arctic drift speed simulations near the ice edge. The ice velocity direction simulation in the Beaufort Gyre and the Pacific and Atlantic sectors of the Southern Ocean in OMIP2 are also improved owing to surface wind stress changes. This study provides clues on how improved atmospheric reanalysis products influence sea ice simulations. Our findings suggest that attention should be paid to the radiation fluxes and winds in atmospheric reanalyses in polar regions.

Xia Lin et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2022-110', Anonymous Referee #1, 05 Jul 2022
    • AC1: 'Reply on RC1', Xia Lin, 16 Sep 2022
  • RC2: 'Comment on tc-2022-110', Anonymous Referee #2, 05 Aug 2022
    • AC2: 'Reply on RC2', Xia Lin, 16 Sep 2022
    • AC3: 'Reply on RC2', Xia Lin, 16 Sep 2022

Xia Lin et al.

Xia Lin et al.

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Short summary
This study provides clues on how improved atmospheric reanalysis products influence sea ice simulations in ocean-sea ice models. The summer ice concentration simulation in both hemispheres can be improved with changed surface heat fluxes. The winter Antarctic ice concentration and the Arctic drift speed near the ice edge and the ice velocity direction simulations are improved with changed wind stress. The radiation fluxes and winds in atmospheric reanalyses are crucial for sea ice simulation.