What RCM Data Are Available for What RCM Data Are Available for California Impacts Modeling?California Impacts Modeling?
(How Good Is It?)(How Good Is It?)
W. J. Gutowski, Jr., Z. Pan, C. Anderson, W. J. Gutowski, Jr., Z. Pan, C. Anderson,
R. W. Arritt, F. Otieno, E. S. TakleR. W. Arritt, F. Otieno, E. S. Takle
Iowa State UniversityIowa State University
J. H. Christensen, O. B. ChristensenJ. H. Christensen, O. B. Christensen
Danish Meteorological Institute Danish Meteorological Institute
Copenhagen, DenmarkCopenhagen, Denmark
California Energy Commission (June 2000)
OutlineOutline
Overview - Regional Climate SimulationOverview - Regional Climate Simulation
Biases as norms for evaluating climate changeBiases as norms for evaluating climate change PrecipitationPrecipitation
TTminmin, T, Tmaxmax
Climate change for selected locations in CAClimate change for selected locations in CA
Conclusions: Ranges for scenariosConclusions: Ranges for scenarios
California Energy Commission (June 2000)
OutlineOutline
Overview - Regional Climate SimulationOverview - Regional Climate Simulation
California Energy Commission (June 2000)
US Simulations Longer Than 1 Year
Authors Driver Res.[km]
Duration[YR]
Giorgi et al. (1993) Analysis 60 2
Giorgi et al. (1994) GCMpresent
60 3.5
GCMscenario
60 3.5
Giorgi et al. (1998) GCMpresent
50 5
GCMscenario
50 5
Giorgi & Shields (1999) Analysis 60 3
Liston & Pielke (1999) Analysis 50 1
Miller et al. (2000) Analysis 36 8
Pan et al. (2000) Analysis 55 10
[2 models] GCMpresent
55 10
GCMscenario
55 10
Simulations
Model Observed GCM-control GCM-Scenario
RegCM2 NCEPReanalysis(1979-1988)
HadleyCentre(~1990’s)
HadleyCentre(2040-2050)
HIRHAM(DMI)
“ “ “
Purpose
Evaluate RCM performance
Compare RCM and GCM projections
Assess U.S. regional climate change uncertainty
OutlineOutline
Overview - Regional Climate Simulation
Biases as norms for evaluating climate changeBiases as norms for evaluating climate change PrecipitationPrecipitation
TTminmin, T, Tmaxmax
California Energy Commission (June 2000)
Reanalysis
HadCMCont/Scen
RegCM2
HIRHAM
Possible Comparisons?
OBS
HadCMCont/Scen
Driving Differences
Seasonal-regional biases
Po, Pm are observed, model precipitation
N is total grids in the region
),,( itmdforcRCM
chng
chng PPPMax
PR
=
Climate change ratio
ΔPRCM =1N
Pim−Pi
o( )
i=1
N
∑
Definitions
California
-3
-2
-1
0
1
2
3
win spr sum aut anu
season
RCM biasforcing biasintermodel biasG-R nesting biasclimate change
RegCM2
0
1
2
3
4
5
6
7
PNW CA MW NE NS
Region
Rchng
winterspringsummerautumn
),,( itmdforcRCM
chng
chng PPPMax
PR
=
OutlineOutline
Overview - Regional Climate Simulation
Biases as norms for evaluating climate change Precipitation
Tmin, Tmax
Climate change for selected locations in CAClimate change for selected locations in CA
California Energy Commission (June 2000)
0
5
10
15
20
OBS-1 NC-1 HCont-1 HScen-1
October - March (RegCM2)
[mm/d]
0
5
10
15
20
OBS-2 NC-2 HCont-2 HScen-2
October - March (RegCM2)
[mm/d]
0
5
10
15
20
OBS-3 NC-3 HCont-3 HScen-3
October - March (RegCM2)
[mm/d]
0
5
10
15
20
OBS-4 NC-4 HCont-4 HScen-4
October - March (RegCM2)
[mm/d]
0
5
10
15
20
OBS-5 NC-5 HCont-5 HScen-5
October - March (RegCM2)
[mm/d]
0
2
4
6
8
OBS-1 NC-1 HCont-1 HScen-1
April-September (RegCM2)
[mm/d]
0
2
4
6
8
OBS-2 NC-2 HCont-2 HScen-2
April-September (RegCM2)
[mm/d]
0
2
4
6
8
OBS-3 NC-3 HCont-3 HScen-3
April-September (RegCM2)
[mm/d]
0
2
4
6
8
OBS-4 NC-4 HCont-4 HScen-4
April-September (RegCM2)
[mm/d]
0
2
4
6
8
OBS-5 NC-5 HCont-5 HScen-5
April-September (RegCM2)
[mm/d]
0
50
100
150
200
250
300
2 4 6 8 10 12
RegCM2 - POINT 3
NCEP-3HCont-3HScen-3
Month
CA Temp Biases:
Tmax - small, mixed Tmax - slightly cool
Tmin - warm (few oC) Tmin - small, mixed
0
100
200
300
400
500
2 4 6 8 10 12
HIRHAM - POINT 3
NCEPHContHScen
Month
OutlineOutline
Overview - Regional Climate Simulation
Biases as norms for evaluating climate change Precipitation
Tmin, Tmax
Climate change for selected locations in CA
Conclusions: Ranges for scenariosConclusions: Ranges for scenarios
California Energy Commission (June 2000)
California Energy Commission (June 2000)
FIELD POSSIBLECHANGE **
CONFIDENCE **
Precipitation + 3-5 mm/d(North)
+ 0-1 mm/d(South)
good
fair
Tmin, Tmax + 2 – 3 oC fair
Snow 0-50%decrease
poor
** = Subject to quality of driving GCM!
Conclusions
Interannual variability in RegCM2 and HIRHAM is less than observed.
Ratio of climate change to biases is especially large in the California region
Differences between RCM and GCM imply room for RCMs to add value to GCM simulations
Regional warming signal is less robust than precipitation change
Future warming projection has large inter-model differences
California Energy Commission (June 2000)