The comparison was done check details at locations of oceanographic monitoring stations that characterize open sea conditions of the corresponding sub-basins (Figure 2). The results of the comparison do not differ significantly when instead of a single grid point the average of several contiguous grid points is considered. As the resolution of the grid on which the SMHI observations are interpolated is rather coarse and as observations over the sea are sparse (only a few stations are located on islands), RCA3-ERA40 model results are not necessarily worse than SMHI data. We focused on the analysis of the mean seasonal cycles at these stations, the interannual variability as expressed by the mean seasonal cycles of the corresponding standard deviations
and on maps of the entire Baltic Sea area showing seasonal mean atmospheric and oceanic surface variables. The quantitative assessment INK 128 clinical trial of atmospheric surface fields is based upon mean biases of atmospheric surface variables at the five selected monitoring stations (Figure 2). We concentrated on variables that are necessary to force an ocean model, i.e. 2 m air temperature, 2 m specific humidity, SLP, adjusted wind speed, total cloudiness and precipitation. Figure 5 shows the mean seasonal cycles
and their variability of 2 m air temperature, SLP, adjusted 10 m wind speed, 2 m specific humidity, total cloudiness and precipitation over the Gotland Deep, characterizing open sea conditions of the eastern Gotland Basin (see Figure 2). Qualitatively similar results were found in the other sub-basins. Further, Figures 6 and 7 show maps of winter mean SLP and of winter and summer mean 2 m air temperature for the entire Baltic Sea area respectively. The mean biases of five
selected variables at five selected monitoring stations (Figure 2) are listed in Tables 3 to 7. We found very good agreement between RCA3-ERA40 model results and the SMHI Astemizole data for 2 m air temperature, SLP, cloudiness and precipitation (Figures 5 to 7 and Tables 3 to 7). Also, the horizontal distributions for SLP (Figure 6) and 2 m air temperature (Figure 7) in the RCA3-ERA40 simulation are close to the gridded observations. However, in winter RCA3 simulated land-sea temperature gradients are larger than observed values. In addition, simulated air temperatures over the sea are about 1°C higher in winter and about 1°C lower in summer than in the observations. Further, the interannual variability of the 2 m air temperature is smaller in the RCA3-ERA40 than in the SMHI data. These results could be explained by biases in the observational data set, because the SMHI data contain only observations from land. The mean adjusted wind speed and its interannual variability are smaller in the RCA3-ERA40 than in the SMHI data (Figure 5). The largest annual mean biases are found in the northern Baltic Sea, where the simulated mean wind speed is underestimated by about 30% compared to the mean 10 m wind speed calculated from observations (Table 5).