Seasonal to yearly assessment of temperature and precipitation trends in the North Western Mediterranean Basin by dynamical downscaling of climate scenarios at high resolution (1971–2050)

The complex topography and high climatic variability of the North Western Mediterranean Basin (NWMB) require a detailed assessment of climate change projections at high resolution. ECHAM5/MPIOM global climate projections for mid-21st century and three different emission scenarios are downscaled at 10 km resolution over the NWMB, using the WRF-ARW regional model. High resolution improves the spatial distribution of temperature and precipitation climatologies, with Pearson's correlation against observation being higher for WRF-ARW (0.98 for temperature and 0.81 for precipitation) when compared to the ERA40 reanalysis (0.69 and 0.53, respectively). However, downscaled results slightly underestimate mean temperature (≈1.3 K) and overestimate the precipitation field (≈400 mm/year). Temperature is expected to raise in the NWMB in all considered scenarios (up to 1.4 K for the annual mean), and particularly during summertime and at high altitude areas. Annual mean precipitation is likely to decrease (around −5 % to −13 % for the most extreme scenarios). The climate signal for seasonal precipitation is not so clear, as it is highly influenced by the driving GCM simulation. All scenarios suggest statistically significant decreases of precipitation for mountain ranges in winter and autumn. High resolution simulations of regional climate are potentially useful to decision makers. Nevertheless, uncertainties related to seasonal precipitation projections still persist and have to be addressed. Climatic Change (2014) 122:243–256 DOI 10.1007/s10584-013-0994-y Electronic supplementary material The online version of this article (doi:10.1007/s10584-013-0994-y) contains supplementary material, which is available to authorized users. M. Gonçalves (*) : D. Guerreiro : J. M. Baldasano Earth Sciences Department, Barcelona Supercomputing Center, Barcelona, Spain e-mail: [email protected] M. Gonçalves : J. M. Baldasano Projects Department, Technical University of Catalonia, Barcelona, Spain A. Barrera-Escoda : J. Cunillera Climate Change Unit, Meteorological Service of Catalonia, Barcelona, Spain