CR 61:1-17 (2014)  -  DOI: https://doi.org/10.3354/cr01232

ABSTRACT: A global climate scenario run based on the IPCC future emission scenario SRES A1B was dynamically downscaled for the North Sea, using an uncoupled meso-scale model system. The atmospheric forcing shows an increase in air temperature during the 21st century with stronger warming in winter than in summer. These trends are reflected by an increase in annual mean sea surface temperature of ~1.8°C. The strong warming in winter is the main driver for the total warming of the North Sea, as indicated by the analysis of surface heat flux components. The thermocline weakens in intensity according to the changing temperature profiles, and its mean depth slightly decreases due to lower wind speeds. The salinity in the North Sea drops by ~0.6 psu because of decreasing salinity of the inflowing Atlantic waters, increasing Baltic discharge, and higher downward surface fresh water fluxes. Some of our results disagree with other dynamical downscaling studies, as the results depend on the parent global model. In general, the downscaled projected trends qualitatively agree with the results of the coarser global model. Nevertheless, in particular, the magnitudes of the surface heat fluxes, the formation of the frontal system, and the strength and structure of the general circulation are more realistically represented in the regional meso-scale model.

KEY WORDS: Dynamical downscaling · North Sea · IPCC SRES A1B · Climate change