Regional climate simulation with a mosaic of RCMs

Abstract

The aim of the present study is to explore the possibility of getting high horizontal resolution over Europe by using a cluster of low computational cost atmospheric general circulation models (AGCM). The approach is based on global models with stretched grid, driven by a medium-resolution model serving as a "conductor" to maintain time consistency of the synoptic events and avoid climate degradation in the low resolution part of the grids. Thus the global models behave as regional climate models (RCM). A perfect model approach is used with a high resolution AGCM serving as a reference. The results show that when the different models are merged on a high resolution grid, the mean climate is similar to what is obtained with an equivalent high resolution AGCM with an unstretched grid. A climate change numerical experiment shows that this is also valid for the climate response to increased greenhouse gas concentration.