Ocean Dynamics 
Ô Springer 
depend on the number of forecasts on the current day. If one 
forecast is missing, the MME mean might change sharply. By 
the middle of February, for instance, the absence of 
METNOROMS for a few days caused a strong decrease of 
the MME mean. The MME median is not affected in that extent. 
In order to explain the severe drop in June and August, 
temporally averaged MME mean and standard deviation over 
this period are compared to the corresponding statistics for 
May (Fig. 16). In May, low-salinity surface water flowing 
out the Baltic Sea is localized close to the Norwegian coast 
where standard deviation is high. Between 24 June and 8 
August, the low-salinity front extends to the center of the 
North Sea. The region with high standard deviation is expand 
ed accordingly. This extension in summer is presented by 
many studies, e.g., (Gustafsson 1997b; Rodhe 1998). The ex 
tension of the low-salinity water leads to the severe drop of 
salinity in June and August shown in Fig. 15. The increase of 
ensemble spread (Fig. 15) is caused by the enlargement of the 
area with high standard deviations (Fig. 16). The comparison 
between the two periods indicates that large errors might occur 
in the simulated extension of the low-salinity water in 
summer. 
3°W 0° 3°E 6°E 9°E 12°E 3°W 0° 3°E 6°E 9°E 12°E 
60° N 
58° N 
56° N 
54° N 
52°N 
50° N 
3°W 0° 3°E 6°E 9°E 12°E 
60° N 
58° N 
56° N 
54° N 
52°N 
50° N 
06/24 - 08/08 
20 4 
3 U W o u 
3 U E 6 U E 9 U E 12 U E 
Fig. 16 Temporally averaged ensemble mean (left) and standard deviation (right) of SSS for the period with small uncertainties (top) and for the period 
with large uncertainties (bottom). The region, which is used for the spatial average (Fig. 15), is marked by the black frame