85th AMS Annual Meeting

Thursday, 13 January 2005: 5:15 PM
Influence of the sea ice thickness distribution on simulated polar climate
Marika M. Holland, NCAR, Boulder, CO; and C. M. Bitz, J. L. Schramm, W. H. Lipscomb, and E. C. Hunke
Polar amplification of warming under increased greenhouse gas scenarios is a common feature of climate models. This amplified response is related to positive feedback mechanisms associated with variations in sea ice cover. As such, the parameterization of sea ice processes which can modify these feedbacks is likely to affect simulated polar amplification and variability. In this study, one such parameterization and its influence on climate and climate sensitivity is investigated. A new version of the Community Climate System Model (CCSM3) has recently been released. This model has a relatively sophisticated sea ice component, including a sub-gridscale ice thickness distribution that accounts for the high spatial variability present in the observed ice cover. This ice thickness distribution (ITD) has the potential to influence climate feedbacks. For example, it explicitly resolves thin ice categories which more easily melt away, exposing the underlying ocean and reducing the albedo. Results from the CCSM3 are presented and the influence of the ITD on control and increasing CO2 simulations are discussed. In particular, high-latitude feedbacks that are modified by the ITD are examined.

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