Simulation of daily variability of surface temperature and precipitation over europe in the current and 2 × Co2 climates using the UKMO climate model

Abstract

As the spatial scales simulated by general circulation models are refined and the parametrizations they employ are improved, greater accuracy can be achieved in their simulations of regional climate and events on short time-scales, and greater confidence attached to their predictions of these for perturbed climates. In the present paper, we examine the daily (interdiurnal) variability of surface temperature and precipitation in Europe simulated by a version of the UK Meteorological Office (Hadley Centre) general circulation model, having 11 levels in the vertical and a horizontal resolution of 2.5°latitude × 3.75° longitude, coupled to a slab ocean, in the current climate and the equilibrium climate for a doubled atmospheric concentration of carbon dioxide. We evaluate the simulation of current conditions by comparison with climatologies and time-series of observed data. In the modified 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 in all seasons shows significant tendencies both to more dry days and to heavier events, with less frequent moderate daily amounts; this is connected with an increase in convective activity. We conclude that simulation of daily variability is strongly dependent on particular local physical processes and hence on the parametrizations used to represent them. While acknowledging deficiencies in the model's performance, we consider that our results are indicative of possible changes for a future climate.