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(a)
(b)
DJF
JJA
JJA
DJF
DJF
DJF
JJA
JJA
Fig. 1 Series of SAT (in K) and precipitation (in mm/month) spatially averaged for the Alps
(a) and Central Europe (b). Winter and summer is presented separately, the four series represent
the two GCM runs (cyan and pink) and the two regional models used to downscale these runs (blue
and red). All series have been smoothed with a 31-year running mean
The higher resolution of the RCM is of particular importance because hydrological
sensitive proxy data that will be used for comparison and provide the basis for
empirical reconstructions are usually only representative of their speci
c regional-to-
local setting.
Two different regional models are used here: MM5 (Gomez-Navarro et al.
2013
)
and CCLM (Rockel and Geyer
2008
) are driven at the domain boundaries by
simulations with global atmosphere-ocean general circulation models (AOGCM).
The CCLM simulation is forced at its lateral boundaries with the Earth System
Model (ESM) ECHAM5-MPIOM-JSBACH (Jungclaus et al.
2010
) for the period
1645
2000. The combined ECHAM5+CCLM model is driven by prescribed
changes in orbital, solar and volcanic forcings as well as changes in land use.
Changes in atmospheric greenhouse gases are interactively calculated by the sub-
model of the carbon-cycle embedded in the ESM itself.
A second regional simulation is performed with the regional climate model
MM5, forced with the AOGCM ECHO-G (Gonz
-
á
lez-Rouco et al.
2003
; Zorita
et al.
2005
) for the period 1
1998. Due to the simpler structure of ECHO-G, only
changes in orbital, solar and greenhouse gas forcings are considered. In the com-
bined ECHO-G+MM5 simulation, greenhouse trace gases are prescribed based on
estimations from ice core data (Fl
-
ckiger et al.
2002
). For comparison also the raw
output of the driving GCMs ECHAM5 and ECHO-G will be presented in addition
to the numerically downscaled (ECHAM5+CCLM and ECHO-G+MM5) for the
sample regions in the results section (cf. Fig.
1
).
We use the downscaled ECHO-G+MM5 output in a Pseudo-Proxy Experiment
[PPE, cf. Rutherford et al. (
2005
) and Smerdon (
2012
) for a review] to assess two
reconstruction methods for precipitation over Europe and the Mediterranean region:
the analog method (Franke et al.
2011
) and BARCAST (Tingley and Huybers
2010
;
Werner et al.
2013
) and their ability to reconstruct Winter (DJF) precipitation sums.
PPEs have the advantage that the experimental conditions, such as proxy distri-
bution and noise, can be tuned and the true target
ü
field is known. This enables
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