8
This note describes how scenario simulations for Central Europe have been
performed with a regional climate model based on global climate model scenario
simulations.
1.3.1.2 Data and Methods
Results from high resolution, multi-ensemble regional climate models are an essential input for many climate impact studies. In the course of the CEDIM (Center for
Disaster Management and Risk reduction Technology) project ‘Flood Hazards in a
Changing Climate’ (Wagner 2013) a multi model ensemble of high resolution 7 km
regional climate simulations for a present (1971–2000) and a near future (2021–
2050) time period were conducted. To assess the climate change on regional scales,
regional climate models (RCMs) were nested into coarser global circulation models
(GCMs). For the bulk of the simulations the ECHAM5/MPI-OM Model in T63
resolution (horizontal grid spacing of approximately 140 × 210 km at mid-latitudes)
served as GCM. ECHAM5 is the fifth-generation atmospheric general circulation
model developed at the Max Planck Institute for Meteorology, in that case it was
coupled to the Max Planck Institute ocean model (MPI-OM). IPCC SRES (Special
Report on Emissions Scenario) A1B forcing scenario served as boundary condition.
The spatial resolution of RCM simulations has steadily increased over the last
decades. In the past, several larger ensembles were carried out to assess climate
change, like for example in PRUDENCE (Christensen and Christensen 2007) with
a resolution of 50 km or ENSEMBLES (Hewitt CD 2005) with a spatial resolution
of 25 km. To get more information on this, please refer to the respective literature.
Using WRF (Weather Research and Forecasting Model) as regional climate
model was one part of the contribution of the Institute of Meteorology and Climate
Research (IMK-IFU) to CEDIM. To set up WRF, different steps had to be conducted to make reliable forecasts. Thus three different runs had to be carried out:
one past climate run, one validating reanalysis run and the final future climate scenario run. Each of these runs had a calculation time of approximately 3 month
(Wagner 2013). Covering Germany and the near surroundings it was possible to
extract modeling results for urban areas (7 × 7 km grid cells) contributing to the
CENTRAL Europe Project. Thus, WRF is used in the following to illustrate the
effect of climate change on urban regions within the area of central Europe
The regional climate model WRF followed a double nesting procedure, where
the coarse nest covered an area of entire Europe with a resolution of about 50 km,
whereas the fine nest consisted of Germany and the near surroundings (Fig. 1.1).
The fine model domain of 174 by 174 grid cells covers an area between 1.5 to
17.5° E and 44.5 to 54.5° N. The model resolution of 7 km implies that every urban
area of interest is covered by at least one grid cell 40 vertical levels where used for
both nests. For further specifications on model physics and modeling proceedings
refer to Berg et al. (2013) and Wagner et al. (2013).
J. Fallmann et al.
This note describes how scenario simulations for Central Europe have been
performed with a regional climate model based on global climate model scenario
simulations.
1.3.1.2 Data and Methods
Results from high resolution, multi-ensemble regional climate models are an essential input for many climate impact studies. In the course of the CEDIM (Center for
Disaster Management and Risk reduction Technology) project ‘Flood Hazards in a
Changing Climate’ (Wagner 2013) a multi model ensemble of high resolution 7 km
regional climate simulations for a present (1971–2000) and a near future (2021–
2050) time period were conducted. To assess the climate change on regional scales,
regional climate models (RCMs) were nested into coarser global circulation models
(GCMs). For the bulk of the simulations the ECHAM5/MPI-OM Model in T63
resolution (horizontal grid spacing of approximately 140 × 210 km at mid-latitudes)
served as GCM. ECHAM5 is the fifth-generation atmospheric general circulation
model developed at the Max Planck Institute for Meteorology, in that case it was
coupled to the Max Planck Institute ocean model (MPI-OM). IPCC SRES (Special
Report on Emissions Scenario) A1B forcing scenario served as boundary condition.
The spatial resolution of RCM simulations has steadily increased over the last
decades. In the past, several larger ensembles were carried out to assess climate
change, like for example in PRUDENCE (Christensen and Christensen 2007) with
a resolution of 50 km or ENSEMBLES (Hewitt CD 2005) with a spatial resolution
of 25 km. To get more information on this, please refer to the respective literature.
Using WRF (Weather Research and Forecasting Model) as regional climate
model was one part of the contribution of the Institute of Meteorology and Climate
Research (IMK-IFU) to CEDIM. To set up WRF, different steps had to be conducted to make reliable forecasts. Thus three different runs had to be carried out:
one past climate run, one validating reanalysis run and the final future climate scenario run. Each of these runs had a calculation time of approximately 3 month
(Wagner 2013). Covering Germany and the near surroundings it was possible to
extract modeling results for urban areas (7 × 7 km grid cells) contributing to the
CENTRAL Europe Project. Thus, WRF is used in the following to illustrate the
effect of climate change on urban regions within the area of central Europe
The regional climate model WRF followed a double nesting procedure, where
the coarse nest covered an area of entire Europe with a resolution of about 50 km,
whereas the fine nest consisted of Germany and the near surroundings (Fig. 1.1).
The fine model domain of 174 by 174 grid cells covers an area between 1.5 to
17.5° E and 44.5 to 54.5° N. The model resolution of 7 km implies that every urban
area of interest is covered by at least one grid cell 40 vertical levels where used for
both nests. For further specifications on model physics and modeling proceedings
refer to Berg et al. (2013) and Wagner et al. (2013).
J. Fallmann et al.