Weather regimes-Moroccan precipitation link in a regional climate change simulation

The local future climate conditions in Morocco under the SRES scenario A1B are studied by using two 30-year time-slice simulations performed by the variable resolution configuration of the global circulation model ARPEGE-Climate. The spatial resolution ranges between 50 and 60 km over the whole country. Firstly, the link between local precipitation and weather regimes in the North Atlantic basin is investigated in terms of mean precipitation and the frequencies of occurrence for wet and intense precipitation days. Then a statistical downscaling approach that uses large-scale fields to construct local scenarios of future climate change is validated in the case of Moroccan winter precipitation. The outputs of experiments carried out from an ensemble of regional climate models are used to assess the uncertainties associated to future climate change. These dynamical downscaling outputs have been also used to test the robustness of the results related to the statistical downscaling technique. Our results concerning the future climate conditions over Morocco show not solely a decrease in mean precipitation but also a change in the precipitation distribution and in extreme events. (C) 2010 Elsevier B.V. All rights reserved.