KLIWAS 
Seite 
-9- 
2 Data and Methods 
Regional ocean models require data as forcing inputs both at their boundaries to the 
atmosphere and at their geographical boundaries. These so-called boundary condi 
tions for the lateral ocean boundaries are provided by a global ocean model and, for 
the interface with the atmosphere by the output of a down-scaled atmospheric model. 
The atmospheric forcing plays a crucial role for the resulting oceanic circulation pat 
tern, since the oceanic circulation of shelf seas like the North Sea and the Baltic Sea 
is mainly wind-driven. 
Comparing 
meteorological 
fields of the 
Ensembles 
regional climate 
models with ERA- 
40-data over the 
North Sea 
2.1 ENSEMBLES Regional Climate Models for the North Sea 
The aim of the ENSEMBLES climate change project, initiated by the European 
Commission is to run multiple regional climate models (van der Linden and Mitchell 
2009). 
For the following analysis the ENSEMBLES data set is used. The official ENSEM 
BLES data base at http://www.ensembles-eu.org/ has been updated occasionally and 
in this analysis data from the latest updates have been used (see Table 1). One excep 
tion is the DMI dataset for 10 m wind, which we obtained directly from DMI (Ole 
Bossing Christensen, pers. communication). For a fair comparison only datasets that 
were interpolated on the common ENSEMBLES spatial grid were used. 
Table 1: The calendar dates of the downloads from the ENSEMBLES database 
(http://www.ensembles-eu.org/) 
Model 
Air tempera 
ture 
Sea level 
pressure 
10 m wind 
Global 
radiation 
Cloud 
cover 
Precipitation 
C4I 
17.09.2009 
17.09.2009 
15.10.2009 
15.10.2009 
15.10.2009 
15.10.2009 
CNRM 
17.09.2009 
17.09.2009 
17.09.2009 
17.09.2009 
17.09.2009 
17.09.2009 
DMI 
18.09.2009 
18.09.2009 
01.10.2010 
18.09.2009 
18.09.2009 
18.09.2009 
ETHZ 
20.10.2009 
30.09.2009 
30.09.2009 
20.10.2009 
30.09.2009 
30.09.2009 
HC3Q0 
30.09.2009 
30.09.2009 
30.09.2009 
30.09.2009 
30.09.2009 
30.09.2009 
HC3Q3 
21.10.2009 
01.10.2009 
01.10.2009 
01.10.2009 
01.10.2009 
01.10.2009 
HC3Q16 
01.10.2009 
01.10.2009 
01.10.2009 
01.10.2009 
01.10.2009 
01.10.2009 
ICTP 
01.10.2009 
01.10.2009 
01.10.2009 
01.10.2009 
No data 
01.10.2009 
KNMI 
01.10.2009 
01.10.2009 
01.10.2009 
01.10.2009 
01.10.2009 
01.10.2009 
METNO 
01.10.2009 
01.10.2009 
01.10.2009 
01.10.2009 
01.10.2009 
01.10.2009 
MPI 
02.10.2009 
02.10.2009 
02.10.2009 
02.10.2009 
02.10.2009 
02.10.2009 
SMHI 
30.06.2010 
29.06.2010 
01.07.2010 
29.06.2010 
30.06.2010 
29.06.2010