final_program_abstracts[1]

11 IMSC Session Program
Dynamical downscaling of future climate change in the
Mediterranean region
Wednesday - Poster Session 5
Andreas Paxian, Gernot Vogt and Heiko Paeth
Geographical Institute, University of Würzburg, Würzburg, Germany
The German KLIWEX-MED project aims to analyse the regional characteristics and
intensity of climate change in the Mediterranean Basin with special focus on extreme
events like heavy precipitation, heat waves and droughts. Corresponding uncertainties
are quantified in a probabilistic sense.
For the investigation of dynamical downscaling, we consider simulations of the global
climate model ECHAM5/MPI-OM (1.875°) as well as simulations of the highresolution
(0.5°) regional climate model REMO which is nested in ECHAM5/MPI-
OM for the time period 1961-2050. As forcing we consider observed GHG emissions
for 1961-2000 and A1b and B1 emission scenarios for 2001-2050.
We present means and trends of seasonal temperature and precipitation of both
REMO and ECHAM5/MPI-OM for the time periods 1961-2000 and 1961-2050. For
the present-day time period the findings are validated with observational data from
CRU TS 2.1 and ENSEMBLES WP5.1. The whole time period presents a projection
of decadal future climate change in the Mediterranean region. In comparing regional
and global climate model results we reveal the added value of high-resolution regional
climate modelling.
To prove if the forcing global climate model ECHAM5 is a representative member of
the multi-model ensemble of the IPCC AR4, its long-term mean and trend for the time
period 1961-2050 are compared to the corresponding multi-model mean values of the
AR4 global climate models interpolated on a common 3°x3° model grid.
In turn, to quantify and test the signal-to-noise ratio of the climate change projection
of the whole multi-model ensemble, the resulting total temperature and precipitation
variability is subdivided by means of two-way analysis of variance into external, as
imposed by radiative forcing, and internal variability, as imposed by different model
parameterisations and initial conditions.
Furthermore, certain differences between present-day REMO and observational trends
can be explained by a deviation of the temporal evolutions of few main large-scale
circulation patterns, mainly the winter NAO, simulated by the forcing model
ECHAM5/MPI-OM from those of recent observations. This deviation has been found
in a seasonal principal component analysis and can be correlated to the mentioned
temperature and precipitation trend differences.
Abstracts 209