Ocean Dynamics 
Ö Springer 
SSC on 20141021 14:00 
Fig. 6 Example of SSC showing the number of forecasts per grid cell (a), the MME mean (b), stability (c), standard deviation between the forecasts (d), 
the angular difference between the MME mean and the MyOcean product, (e) and the difference-to-standard-deviation ratio (f) for the North Sea 
availability of satellite data is still low, reaching only 28 % in 
June. During these 2 months, high values and large spread of 
RMSDs among the forecasts are shown, although the avail 
ability of satellite observations is different (Figs. 8 and 9). 
There might exist local dependency between available satellite 
data and the errors, but it is not reflected in the comparison of 
the monthly mean values. 
The RMSDs of the ensemble members have the largest 
differences in August (Fig. 9). Flence, the spatial distribution 
of RMSDs of the MME mean and the individual forecasts is 
evaluated for this month (Fig. 10). Fligh RMSDs are found in 
the southeast of the North Sea for METNOROMS, while 
high values of DMI DKSS occur in the northwestern part of 
the North Sea. Moreover, high RMSDs in the area close to the 
eastern British coast occur only for BSHCMOD, 
SMHIHIROMBNS03, and DMI DKSS. The RMSD of 
the MME mean is lowest compared to the individual forecasts 
and distributed evenly with errors less than 0.5 °C at most grid 
points. No distinct area with high RMSD is reflected for the 
MME mean (Fig. 10). It shows that the ensemble process 
helps to reduce the error. In order to fully understand the 
mechanisms influencing the forecast uncertainties including 
seasonal features, the atmospheric forcing of each forecast 
needs to be taken into account, which is not part of this study. 
The large spread of spatially averaged monthly mean 
RMSDs in June, July, and October is due to large differences 
in the spatial distribution of RMSDs for each product. For 
instance, in June, almost all forecasts except for DMI DKSS 
have large errors in the central North Sea. The RMSDs of 
SMHI HIROMB NS03 and METNO ROMS are close to 
2 °C in this area, while those of the other forecasts vary be 
tween 1.25 and 1.75 °C, In July, BSHCMOD, BSH HBM, 
and DMI DKSS have large errors in the area close to the 
eastern British coast, which is not reflected by the other