Validation of the surface energy balance over the Antarctic ice sheets in the U.K. Meteorological Office Unified Climate Model

Surface radiation measurements and other climatological data were used to validate the representation of the surface energy balance over the East Antarctic Ice Sheet in the U.K. 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 W m−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 that prevail in the Antarctic boundary layer.