The climate of antarctica in the UGAMP GCM: Sensitivity to topography

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Abstract
Most spectral general circulation models (GCMs) use an envelope topography to set on land surface elevations. The UK Universities Global Atmospheric Modelling Programme General Circulation Model (UGAMP GCM) uses such a formulation for Antarctica, based on the US Navy 10 are minute charts of the region. In the marginal regions of the continent, an envelope topography consistently overestimates the elevation leading to lower-than-observed surface temperatures. Furthermore, errors in excess of 1000 m exist in the US Navy data, and the UGAMP GCM treats the major ice shelves as sea ice, introducing a 12% reduction in the snow-covered area of the continent. Here, we use a new high-resolution, high-accuracy digital elevation model to improve the representation of Antarctica in the UGAMP GCM. The effect of changing the land–sea mask and the topography on the surface temperature, precipitation and wind held is investigated for both summer and winter runs. Changing the land–sea mask had a dramatic effect on temperature, producing a reduction of 13.3°C for the sector west of the Ross Ice Shelf. Using the new mean topography also introduces substantial differences in temperature, wind speed and precipitation for summer and winter.