A Variable-Resolution, global configuration of the Community Earth System Model (VR-CESM) in which the atmosphere and land are the only active components is employed to investigate the climate of the Euro-Mediterranean region. Two variable-resolution grids with regionally-refined resolutions of 0.25° and 0.125° over the study domain, respectively, are used. The fidelity of these VR-CESM simulations is evaluated considering the near-surface air temperature and precipitation fields for the 2000-2014 period in comparison to available observation-based datasets and those of a coarse resolution (quasi-uniform 1°) control simulation. Our analysis shows that, as a global model, VR-CESM is a promising alternative to regional climate models to advance our understanding of the Euro-Mediterranean climate. The improvements obtained are mainly related to a better representation of the complex topography of the region with higher resolution. Increasing the regional resolution to 0.25° generally yields considerable improvements over the control simulation, however some persistent biases remain. Doubling the highest resolution to 0.125° leads to only modest improvements, primarily in the representation of small-scale processes including representation of extreme events that are of substantial relevance for the present and future of the regional climate.

The Arctic climate is changing dramatically, especially in terms of sea ice loss, with potentially large downstream impacts on the Nordic Seas and the North Atlantic Ocean. The East Greenland Current (EGC) transports substantial amounts of freshwater (in liquid and solid states) southward along the east Greenland continental slope. To increase our understanding of the drivers of surface salinity changes in the interior Nordic Seas, we investigate the diversion of freshwater from the EGC into the Nordic Seas. To this end, we analyse the outcomes of an ocean model hindcast for the period 1973-2004 with a horizontal resolution of 0.25 degree. We find that sea ice contributes large amounts of freshwater to the interior Nordic Seas. On an interannual time scale, this sea ice diversion has a high and significant correlation with surface salinity in the Greenland and Iceland Seas (correlation < -0.7). On a seasonal time scale, the model hindcast and observations demonstrate a clear signal in surface salinity: a lateral migration of the Polar Front position occurring along all of east Greenland. In the model hindcast, these lateral shifts in the front are consistent with seasonal changes in the westward wind-driven Ekman transport. Thus, this climate model study indicates that there are two main causes of seasonal and interannual surface salinity changes; wind-driven Ekman transport and sea ice diversion from the EGC, respectively.