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Sensitivity studies with a statistical downscaling method, the role of the
driving large scale model
Frank Kreienkamp, Arne Spekat and Wolfgang Enke
Climate & Environment Consulting Potsdam GmbH, Telegrafenberg A31, 14473 Potsdam,
frank.kreienkamp@cec-potsdam.de
The sensitivity of the statistical downscaling method
WETTREG (Enke et al. 2005a, Enke et al. 2005b), will
be presented and compared with results of the regional
models REMO and CCLM.
WETTREG analyzes the time evolution of circulation
pattern frequencies in climate model control runs and
scenarios and its consequences for local climate
parameters. Several global models (BCCR, CGCM, and
ECHAM) and one regional model (CCLM) have been
used in their pattern-generating capacity to derive the
WETTREG input. Moreover, several generations and
runs of the same model are analyzed. In an additional
experiment, an extrapolation of the recent trends in
pattern frequency into the near future and the resulting
short-term temperature and precipitation trends are
investigated. The results show model-dependent
distinctive features concerning the reconstruction of the
current climate, albeit of small magnitude. With respect
to short-term climate trends for the target time frame
2011--2030, the model-specific bandwidth is strongest in
winter and weakest in summer when temperature is
concerned (Figure 1 and 2) and rarely leaves an ± 10%
envelope when percentual change of precipitation is
concerned (Spekat et al. 2008).
respect to data acquisition and H.-J. Panitz of the
Karlsruhe Research Center with respect to CCLM data
processing. The data from the climate stations are
courtesy of the German Weather Service.
Figure 2: Ring diagram of the temperature variance
computed for the time frame 2010--2030 (scenario
A1B) minus 1971--2000 (20C control run) across
all models investigated. The outer ring depicts the
monthly values, the middle ring gives the seasonal
values and the center dodecahedron shows the
variance of the annual temperature.
Figure 1: Ring diagram of the temperature signal
for the time frame 2010--2030 (scenario A1B)
minus 1971--2000 (20C control run) across all
models investigated. The outer ring depicts the
monthly values, the middle ring gives the seasonal
values and the center dodecahedron shows the rise
in annual temperature.
Acknowledgements
This work was made possible by funds from the State of
Baden-Württemberg, grant 23-8801.10. The authors
further acknowledge the assistance of A. Hense, R.
Hagenbrock and C. Schölzel of the Bonn University with
References
Enke, W.; Deutschländer, Th.; Schneider, F.: Results of
five regional climate studies applying a weather
pattern based downscaling method to ECHAM4
climate simulations. Meteorol Z, Vol. 14, S. 247-257,
DOI: 10.1127/0941-2948/2005/0014-001. 2005
Enke, W.; Schneider, F.; Deutschländer, Th.: A novel
scheme to derive optimised circulation pattern
classifications for downscaling and forecast purposes.
Theoretical and Applied Climatology, DOI:
10.1007/s00704-004-0116-x. 2005
Spekat, A.; Enke, W.; Kreienkamp, F. : Probabilistische
Abschätzung regionaler Klimaänderungen der
kommenden Dekaden und ihre Unsicherheiten
(PArK): Anwendung von Methoden zur Abschätzung
regionaler Klimaänderungen der kommenden
Dekaden, Szenarienrechnungen mit WETTREG.
Abschlussbericht. Im Auftrage des Landes Baden-
Württemberg, vertreten durch das
Umweltministerium (UM), dieses vertreten durch die
Landesanstalt für Umwelt, Messungen und
Naturschutz Baden-Württemberg, Karlsruhe. AZ 23-
8801.10. 40pp. 2008