Sensitivity of sea ice thickness to observational constraints on sea ice concentration

TitleSensitivity of sea ice thickness to observational constraints on sea ice concentration
Publication TypeTechnical memorandum
Date Published09/2013
Secondary TitleECMWF Technical Memoranda
AuthorsTang, YM, Alonso-Balmaseda, M, Mogensen, K, Keeley, S, Janssen, PAEM

Sea ice is an integral part of the global climate system, its initialisation through the assimilation of available data is crucial for obtaining reliable seasonal and monthly forecasts. This paper reports three contrasting sea ice numerical experiments. These are a forced reference simulation, without any sea ice data assimilation, and two simulations where the sea ice concentration from observations is used to constrain the numerical model via different nudging schemes. One nudging scheme has a spatially uniform relaxation time scale, while the other has a spatially and time varying relaxation time scale. While both nudging schemes efficiently constrain the sea ice extent, the ice thickness remains largely unconstrained, the two nudging experiments giving different solutions. Comparison of the sea ice thickness with satellite observations suggests that the simulation with the spatially varying nudging scheme produces more realistic patterns than the simulation with a uniform nudging scheme; with a marginal improvement over the reference simulation.

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