KLIWAS 
Seite 
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1 Mo tiva tio n 
Shipping and other economic uses of the oceans, protection of the coasts and coastal 
infrastructures as well as biogeochemical processes in the ocean are vulnerable to 
climate change. In order to provide the basic physical parameters that are relevant for 
the development of adaptation measures for the North and the Baltic Sea, the possible 
evolution of the future oceanographic and meteorological status of these two seas 
need to be known. 
Global climate models that were used in the Fourth Assessment Report of the Inter 
governmental Panel on Climate Change (Solomon et al. 2007) had rather coarse spa 
tial resolution and were thus not ideally suited to identify climate change signals in 
regional seas like the North and the Baltic Sea. Therefore, dynamical downscaling of 
climate model output is required to incorporate physical processes important on re 
gional and local scale and to obtain high resolution output. 
The European ENSEMBLES project (Hewitt and Griggs) carried out a comprehen 
sive downscaling exercise for the European region using 15 different regional atmos 
pheric models from different research institutions. However, the primary target of 
ENSEMBLES was the atmosphere over land areas and not over the adjacent seas and 
oceans. In addition, most validation studies have focused on land areas only (e.g. Dé- 
qué 2011, Jacob 2007, Nikulin 2010, Raisanen 2012). Therefore, the KLIWAS re 
search programme of the German Federal Ministry of Transport, Building and Urban 
Development (BMVBS) within its marine work packages 1.03 1 and 2.01 1 2 has investi 
gated the spread of ENSEMBLES climate projections in the North Sea area (read 
more at www.kliwas.de). 
Within KLIWAS as a first step the atmospheric fields close to the sea surface from 
the ENSEMBLES hindcast simulations forced with ERA-40 data were validated. 
Since these atmospheric fields are used as boundary conditions for ocean models, 
these atmospheric parameters have great impacts on the ocean model results and their 
bandwidth of future prediction of the possible oceanographic status of the North Sea, 
e.g. on the water temperature and circulation patterns and, subsequently on the devel 
opment of appropriate practical adaptation measures. 
This report presents the results of a comprehensive assessment of a variety of relevant 
atmospheric parameters in comparison to the ERA-40 reanalysis that is used as forc- 
1 WP 1.03: Atmospheric and Oceanic Reference Data and Climate Projections for Coastal and Open 
Sea Areas 
2 
WP 2.01: Climate Change Scenarios for the Maritime Area and their Parametrisation 
Comparing 
meteorological 
fields of the 
Ensembles 
regional climate 
models with ERA- 
40-data over the 
North Sea