British Antarctic Survey, High Cross, Cambridge, CB3 OET, UK
We consider the mass balance of Antarctica as represented by the UKMO Global Climate Model. This model has a qualitatively realistic simulation of accumulation over Antarctica, and reproduces the broad- scale features of a desert region over the interior plateau and a coastal zone of high snowfall. The model is atmosphere-only, and does not represent effects such as drifting snow or ice movement. The accumulation balance is therefore between snowfall and sublimation/deposition. We show that the model is sensitive to changes in the diffusion scheme and other parameterisations, which can produce large variations in the accumulation. We then ask, If we cannot select amongst these parameterisations on physical grounds and have to tune the model to the current climate, how reliable will the model be in predicting responses to climatic change?