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The Role of Sea Ice Thermodynamics in the Northern Hemisphere Climate

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The Role of Sea Ice Thermodynamics in the Northern Hemisphere Climate The role of sea ice thermodynamics in the Northern Hemisphere climate as simulated by a global coupled ocean-atmosphere model Yvonnick Leclainche, Pascale Braconnot, Olivier Marti, Sylvie Joussaume, Jean-Louis Dufresne, Marie-Angèle Filiberti To cite this version: Yvonnick Leclainche, Pascale Braconnot, Olivier Marti, Sylvie Joussaume, Jean-Louis Dufresne, et al.. The role of sea ice thermodynamics in the Northern Hemisphere climate as simulated by a global coupled ocean-atmosphere model. [Other] Notes scientifiques du Pôle de modélisation du climat. 21, IPSL. 2001. hal-03319449 HAL Id: hal-03319449 https://hal.archives-ouvertes.fr/hal-03319449 Submitted on 12 Aug 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. 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Le Clainche1 (*), P. Braconnot1 (*), O. Marti1, S. Joussaume1, J-L. Dufresne2 and M-A. Filiberti3 1 IPSL/LSCE - Laboratoire des Sciences du Climat et de l'Environnement, UMR 1572 CEA-CNRS, Orme des Merisiers, 91191 Gif sur Yvette Cedex, France 2 IPSL/LMD - Laboratoire de Métérologie Dynamique, Université Paris VI, Case 99, 4 place Jussieu, 75252 Paris Cedex 05, France 3 IPSL / LODYC - Laboratoire d'Océanographie Dynamique et de Climatologie, Université Paris VI, Case 100, 4 place Jussieu, 75252 Paris Cedex 05, France (*) Corresponding authors, e-mail : [email protected] or [email protected] 1 Abstract: We investigate the role of sea ice in the Northern Hemisphere climate as simulated by the IPSL coupled ocean-atmosphere model. A complex thermodynamic parameterization of sea ice has been introduced in this global model. Our study is based on the comparison of a simulation performed with this new version, with an earlier one that only differs by the sea-ice scheme. Our results demonstrate not only the need to include an efficient thermodynamic sea ice model in global coupled ocean-atmosphere models, but also the large impact of the sea ice on the climate system. The thermal inertia of sea-ice plays a role as important as the sea-ice albedo feedback and the insulator effect of sea ice. It needs to be accounted for to get a good representation of the seasonal cycle of sea-ice cover. This inertia is modulated by the heat budgets at the bottom and surface of the ice and by the energy absorbed into leads. In our simulations, the sea-ice has an impact on the atmospheric circulation in the Arctic and North Atlantic and on the hydrological cycle, which strongly affects the surface and thermohaline ocean circulation in the Atlantic. The transport of heat and salt from the North Atlantic to the Norwegian sea and the seasonal ice brine rejection favor the deep convection in the Norwegian sea during the winter. They have a key role in the model and strengthen the ocean equator to pole heat transport. 1. Introduction Sea ice is a major component of the climate system at high latitudes. It has a strong impact on the coupled interactions between the atmosphere and the ocean (e.g. Van Ypersele 1990). When sea ice is present, the radiative properties of the surface are modified compared to free ocean conditions. Its high albedo (between 0.6 and 0.9) limits the amount of absorbed solar energy at the surface. Short-wave radiation penetrating into sea ice is mainly converted into latent energy, and only a small part can reach the ocean through the thinnest sea ice. The snow and ice surface temperature can drop down to -30oC or less in winter, which contrasts with the relatively warmer sea surface temperature that remains above the seawater freezing point (~ -1.8oC).
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