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Aristeidis G. Koutroulis, Aggeliki-Eleni K. Vrohidou, and Ioannis K. Tsanis

:// ), regarding the climate change (precipitation data) in each area. A regional climate model resolves small-scale atmospheric circulations and simulates atmospheric processes on diverse time scales using boundary conditions that are provided by global climate model simulations, observations, global analysis, and reanalysis products ( Larsén et al. 2008 ). The ENSEMBLES RCMs were used to perform the downscaling of the results of global climate simulations to the regional scales. Thus, models were

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Philippe Lucas-Picher, Jens H. Christensen, Fahad Saeed, Pankaj Kumar, Shakeel Asharaf, Bodo Ahrens, Andrew J. Wiltshire, Daniela Jacob, and Stefan Hagemann

-resolution climate simulations has consisted of the use of a regional climate model (RCM) to dynamically downscale a GCM simulation or a reanalysis (e.g., Giorgi 2006 ). By using a domain covering a certain region of the globe, the RCMs are able to efficiently perform a climate simulation at a horizontal resolution of typically 50 km or less. While being controlled by the large-scale boundary conditions taken from a GCM or a reanalysis, the RCMs take advantage of their higher resolution to improve the

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Lukas Gudmundsson, Lena M. Tallaksen, Kerstin Stahl, Douglas B. Clark, Egon Dumont, Stefan Hagemann, Nathalie Bertrand, Dieter Gerten, Jens Heinke, Naota Hanasaki, Frank Voss, and Sujan Koirala

hydrology models (GHMs), focusing on closing the water balance for the purpose of water resource assessment, and land surface models (LSMs) that were historically developed to provide lower boundary conditions for atmospheric circulation models with a focus on the surface water and energy balances. However, many models (both GHMs and LSMs) share essentially the same conceptualization of the water fluxes ( Haddeland et al. 2011 ). Thus, all models that resolve the terrestrial part of the water cycle at

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Kerstin Stahl, Lena M. Tallaksen, Lukas Gudmundsson, and Jens H. Christensen

the European FRIEND project, which is part of the FRIEND initiative of the UNESCO International Hydrological Programme. It includes records from relatively small catchments that represent local conditions and relatively natural flows. The database was recently updated to 2004 ( Stahl et al. 2008 ) and is now held at the GRDC ( ), which also manages data requests. The selection for each country was done by the national agencies, which were also responsible for data quality

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Wai Kwok Wong, Stein Beldring, Torill Engen-Skaugen, Ingjerd Haddeland, and Hege Hisdal

ECHAM4/Ocean Isopycnal Model (OPYC3) developed at the Max Planck Institute for Meteorology (MPI; Roeckner et al. 1999 ) in Germany and the Hadley Centre Atmospheric Model, version 3, high resolution (HadAM3H) coupled with boundary conditions from the third climate configuration of the Met Office Unified Model (HadCM3) both developed at the Met Office's Hadley Centre (HAD; Gordon et al. 2000 ) in the United Kingdom. MPI has a good reproduction of the Norwegian present climate with dominant westerly

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Stefan Hagemann, Cui Chen, Jan O. Haerter, Jens Heinke, Dieter Gerten, and Claudio Piani

least for precipitation, an impact of the bias correction on the climate change signal may be reasonable. For temperature, the assumption of relating current-day model and observed variability differences to future scenario sensitivity to changes in GHG boundary conditions has yet to be verified. For precipitation, this is a similar problem but the situation becomes even more complicated because additional current-day model and observational variabilities affect the signal, and deriving the transfer

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D. Gerten, J. Heinke, H. Hoff, H. Biemans, M. Fader, and K. Waha

conditions of future climate and population change [Special Report on Emissions Scenarios (SRES) A2, the second climate configuration of the Met Office Unified Model (HadCM2)], many countries in northern Africa, the Near East, and southern Asia will turn to a water-scarce status. Further, Rockström et al. (2009) assumed that countries with less than 1300 cubic meters per capita per year of total green and blue water resources cannot produce a balanced diet of 3000 kilocalories per capita per day [1

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Ingjerd Haddeland, Douglas B. Clark, Wietse Franssen, Fulco Ludwig, Frank Voß, Nigel W. Arnell, Nathalie Bertrand, Martin Best, Sonja Folwell, Dieter Gerten, Sandra Gomes, Simon N. Gosling, Stefan Hagemann, Naota Hanasaki, Richard Harding, Jens Heinke, Pavel Kabat, Sujan Koirala, Taikan Oki, Jan Polcher, Tobias Stacke, Pedro Viterbo, Graham P. Weedon, and Pat Yeh

into account anthropogenic impacts such as water withdrawals and dams. Hence, WaterMIP provides an opportunity to compare results of LSMs and GHMs, focusing on differences between the two model strategies, while additionally investigating the effects of anthropogenic impacts on the global terrestrial water balance. Estimates of water availability and stress, as well as the uncertainties thereof, will also be compared for both current and future conditions. Using a range of model simulations, the

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Christel Prudhomme, Simon Parry, Jamie Hannaford, Douglas B. Clark, Stefan Hagemann, and Frank Voss

in mean conditions ( Wilby et al. 2008 ; Sheffield and Wood 2008b ). Furthermore, changes to extremes are of significant importance to society; in reality, researchers, policy makers, and planners are more interested in hydrological extremes than mean conditions. Droughts and floods have had significant impacts in Europe in the recent past: the cost of the 2003 drought in Europe to the agricultural and forestry sectors was estimated at 13.1 billion Euros (EUR), and the drought and heat wave

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Pete Falloon, Richard Betts, Andrew Wiltshire, Rutger Dankers, Camilla Mathison, Doug McNeall, Paul Bates, and Mark Trigg

, although simulations using the previous version HadCM3 were also included in Solomon et al. (2007) . HadGEM1 and HadCM3 are described in detail by Johns et al. (2003 , 2006) and Martin et al. (2006) . HadGEM1 has many improvements over HadCM3, including improved horizontal latitude–longitude resolution (atmosphere: 1.25° × 1.875° versus 2.5° × 3.75°; ocean: 1.0° × 1.0° versus 1.25° × 1.25°) and substantially improved representations of physical processes including advection, boundary layer

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