Evaluation of the simulation of the annual cycle of Arctic and Antarctic sea ice coverages by 11 major global climate models

[1] Comparison of polar sea ice results from 11 major global climate models (GCMs) and satellite-derived observations for 1979–2004 reveals that each of the models is simulating annual cycles that are phased at least approximately correctly in both hemispheres. Each is also simulating various key aspects of the observed ice cover distributions, such as winter ice not only throughout the central Arctic basin but also throughout Hudson Bay, despite its relatively low latitudes. However, some of the models simulate too much ice, others simulate too little ice (in some cases depending on hemisphere and/or season), and some match the observations better in one season versus another. Several models do noticeably better in the Northern Hemisphere than in the Southern Hemisphere, and one does noticeably better in the Southern Hemisphere. In the Northern Hemisphere all simulate monthly average ice extents to within ±5.1 10 km of the observed ice extent throughout the year; in the Southern Hemisphere all except one simulate the monthly averages to within ±6.3 10 km of the observed values. All the models properly simulate a lack of winter ice to the west of Norway; however, most obtain more ice immediately north of Norway than the observations show, suggesting an under simulation of the North Atlantic Current. The spread in monthly averaged ice extents among the 11 model simulations is greater in the Southern Hemisphere than in the Northern Hemisphere and greatest in the Southern Hemisphere winter and spring.