Validation of the Surface Energy Balance over the Antarctic Ice Sheets in the UK Meteorological Office Unified Climate Model

J.C. King and W.M. Connolley

British Antarctic Survey , Cambridge, UK.

Journal of Climate, 1997 (in press)


We use surface radiation measurements and other climatological data to validate the representation of the surface energy balance over the East Antarctic Ice Sheet in the UK Meteorological Office Unified Climate Model. Model calculations of incident and reflected shortwave radiation are in good agreement with observations, but the downward component of longwave radiation at the surface appears to be underestimated by up to 20 Wm-2 in the model. Over much of the interior of Antarctica this error appears to be compensated for by an overestimate in turbulent transport of heat to the surface while, over the steep coastal slopes, the heat flux is in good agreement with observations but the surface temperature is too low. The excessive heat flux over the interior results largely from the use of an inappropriately large bulk transfer coefficient under very stable conditions, suggesting that the surface heat flux scheme in the model is not ideally formulated for the conditions which prevail in the Antarctic boundary layer.

The diagram below shows modelled and observed annual mean energy balance components at the South Pole, in watts per square metre. Modelled and observed short-wave radiation fluxes (Sd, Su) are seen to be in good agreement, while modelled downward longwave radiation (Ld) is too small. This is compensated for by the GCM generating an anomalously large downward sensible heat flux, Hs.

This study was carried out in collaboration with the Hadley Centre for Climate Prediction and Research

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