The performance of the regional climate model CLM in different climate regions, based on the example of precipitation

Abstract

Based on the example of precipitation, we have examined the transferability of the Climate Local Model (CLM) to different regions of the earth. With the exception of the polar climates, all climate zones on earth are taken into account. As expected, the quality of the simulations for temperate and continental climates is similar to those over Europe. Tropical climates, however, display systematic differences with a land-sea contrast. Here, precipitation is overestimated over warm oceans and underestimated over land. Another similarity in all regions is the positive bias in precipitation occurring over high and narrow mountain ranges which stand perpendicular to the main wind direction. In these cases, the CLM produces higher precipitation values than those given in the Global Precipitation Climatology Project (GPCP) data set. A comparison to three other regional climate models indicates that the findings are not CLM-specific. It also stresses the major role of the convection scheme in tropical regions. The present study confirms the assumption that in order to gain optimal results, one standard model setup is not appropriate for all climate zones. It also points out those areas where the standard model setup should be modified.