High resolution climate simulation over Europe

Three AMIP-type 10 year simulations have been performed with climate versions of the ARPEGE-IFS model in order to simulate the European climate. The first one uses the standard T42 truncation. The second one uses a high resolution T106 truncation. The horizontal resolution of the third one varies between about T200 over Europe and T21 over the southern Pacific. The winter time general circulation improves in the Atlantic sector as the resolution increases. This is true for the time-mean pattern and for the transient and low-frequency variability. In summer time and in the southern hemisphere, the 3 versions of the model produce reasonable climatologies. When restricted to the European continent, the model verification against the observed climatology shows a reduction of the biases in temperature and, to a lesser extent, in precipitation with the increase in resolution. The use of a variable resolution GCM is a valid alternative to model nesting. The model is too warm in winter and too cold in summer, too wet in northern Europe and too dry in southern Europe.