SIMULATION OF DAILY VARIABILITY OF SURFACE-TEMPERATURE AND PRECIPITATION OVER EUROPE IN THE CURRENT AND 2XCO(2) CLIMATES USING THE UKMO CLIMATE MODEL

As the spatial scales simulated by general circulation models are refi ned and the parametrizations they employ are improved, greater accurac y can be achieved in their simulations of regional climate and events on short timescales, and greater confidence attached to their predicti ons of these for perturbed climates. In the present paper, we examine the daily (interdiurnal) variability of surface temperature and precip itation in Europe simulated by a version of the UK Meteorological Offi ce (Hadley Centre) general circulation model, having 11 levels in the vertical and a horizontal resolution of 2.5 degrees latitude x 3.75 de grees longitude, coupled to a slab ocean, in the current climate and t he equilibrium climate for a doubled atmospheric concentration of carb on dioxide. We evaluate the simulation of current conditions by compar ison with climatologies and time-series of observed data. In the modif ied climate, we find reductions in temperature variability in winter, related to a lessened land-sea temperature contrast, and increases in summer, caused by changes in the surface heat balance. Precipitation i n all seasons shows significant tendencies both to more dry days and t o heavier events, with less frequent moderate daily amounts; this is c onnected with an increase in convective activity. We conclude that sim ulation of daily variability is strongly dependent on particular local physical processes and hence on the parametrizations used to represen t them. While acknowledging deficiencies in the model's performance, w e consider that our results are indicative of possible changes for a f uture climate.