SIMULATION OF CLIMATE-CHANGE OVER EUROPE USING A GLOBAL VARIABLE RESOLUTION GENERAL-CIRCULATION MODEL

This study presents results from a downscaling simulation of the impac t of a doubling of CO2 concentration. A multidecadal coupled simulatio n of a 1% per year increase of CO2 concentration with the Hadley Centr e ocean-atmosphere model provides its sea-surface temperatures and dee p soil climatological temperatures as a boundary condition to two 10-y ear integrations with a version of the ARPEGE-IFS atmosphere model. Th is global spectral model has a horizontal resolution varying between 6 0 km in the Mediterranean Sea and 700 km in the southern Pacific. The global impact as well as the regional impact over Europe in this time slice are examined and compared with results from other studies. Over Europe, our main focus, the model impact consists of a warming of abou t 2 degrees C, relatively uniform and with little seasonal dependence. There are precipitation increases of about 10% over the northern part in winter and spring, and 30% over the southern part in winter only. Precipitation decreases by 20% in the southern part in autumn. The day -to-day variability of the precipitation increases, except over the so uthern area in summer. No strong impact is found on the soil moisture. Budgets of physical fluxes are examined at the top of the atmosphere and at the land-atmosphere interface.