The projected changes in the surface energy budget of the CMIP5 and Euro-CORDEX models: are we heading toward wetter growing seasons in Central Europe?

Abstract

Abstract We analyze the surface energy budget from two ensembles of climate models and its future changes in the 21st century under the RCP8.5 scenario. High-resolution Euro-CORDEX regional climate models (RCMs) and their driving CMIP5 global climate models (GCMs) are first tested in Central Europe against gridded observational datasets. Evaluation reveals the added value of RCMs in terms of spatial variability and smaller biases. GCMs are affected by the positive bias of global irradiance that propagates into other radiation and heat fluxes. There are strong differences in the projected surface energy budget components between GCMs and RCMs. There is an increase in global irradiance for most of the year in GCMs that is translated into a year-round enhancement of the absorbed solar energy and balanced by higher latent heat flux, except in summer, when the sensible heat flux rises strongly. Together with strong warming and reduced precipitation in summer, this leads to warm, sunny, and dry conditions with reduced evapotranspiration and higher drought stress for vegetation. In the RCMs, the reduction in global irradiance dominates, and it is translated into a round-year reduction in the net balance of longwave radiation and stronger latent heat flux. The first months of the growing season show weaker warming associated with higher rainfall and evapotranspiration. In summer, precipitation drops, and global irradiance and warming rise, but they fall behind the changes in the GCMs. There are no visible signs of conditions leading to a reduction in evapotranspiration or a shortage of soil water in the RCMs in summer.