1. What RCM Data Are Available for California Impacts Modeling
What RCM Data Are Available for California Impacts Modeling? (How Good Is It?)
W. J. Gutowski, Jr., Z. Pan, C. Anderson,
R. W. Arritt, F. Otieno, E. S. Takle
Iowa State University
J. H. Christensen, O. B. Christensen
Danish Meteorological Institute
Copenhagen, Denmark
California Energy Commission (June 2000)

2. Outline Overview - Regional Climate Simulation
Biases as norms for evaluating climate change
Precipitation
Tmin, Tmax
Climate change for selected locations in CA
Conclusions: Ranges for scenarios
California Energy Commission (June 2000)

3. Outline Overview - Regional Climate Simulation
California Energy Commission (June 2000)

4. What is an RCM? Much like a GCM but ...

5. Sample RCM Output

6. DX = 250 km
contours every m

7. DX = 50 km
contours every m

8. DX = 10 km
contours every m

9. US Simulations Longer Than 1 Year

10. Simulations

11. Domain

12. Purpose Evaluate RCM performance Compare RCM and GCM projections
Assess U.S. regional climate change uncertainty

13. Outline Overview - Regional Climate Simulation
Biases as norms for evaluating climate change
Precipitation
Tmin, Tmax
California Energy Commission (June 2000)

14. Possible Comparisons? Reanalysis RegCM2 OBS HadCM Cont/Scen HIRHAM
Driving
Differences

15. RCM (performance) bias
Definition of Biases
Reanalysis
RegCM2
OBS
RCM (performance) bias

16. Definition of Biases
Reanalysis
RegCM2
Inter-model
bias
HIRHAM

17. Definition of Biases
Reanalysis
RegCM2
Forcing
bias
HadCM
RegCM2

18. Definition of Biases
G-R
nesting
bias
RegCM2
HadCM
HadCM

19. Climate Change
HadCM
control
RegCM2
Change
HadCM
scenario
RegCM2

20. Climate Change P
Change
Control
Scenario

21. Climate Change P
Change
Max Bias
Control
Scenario

22. Analysis Regions

23. Seasonal-regional biases
Definitions
Seasonal-regional biases
Po, Pm are observed, model precipitation
N is total grids in the region
Climate change ratio

27. Tmin, Tmax biases

28. Outline Overview - Regional Climate Simulation
Biases as norms for evaluating climate change
Precipitation
Tmin, Tmax
Climate change for selected locations in CA
California Energy Commission (June 2000)

32. Analysis Points 1 2 3 4 5

33. Distribution:Monthly Precipitation

37. CA Temp Biases:
Tmax - small, mixed Tmax - slightly cool
Tmin - warm (few oC) Tmin - small, mixed

38. Other Models?
OBS
PIRCS
(1993)
(1993)
[mm]

39. PIRCS
(1993)
[mm]

40. PIRCS
(1993)
[mm]

41. Outline Overview - Regional Climate Simulation
Biases as norms for evaluating climate change
Precipitation
Tmin, Tmax
Climate change for selected locations in CA
Conclusions: Ranges for scenarios
California Energy Commission (June 2000)

42. ** = Subject to quality of driving GCM!
California Energy Commission (June 2000)

43. 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)

44. Acknowledgments Primary Funding: Additional Support:
Electric Power Research Institute (EPRI)
Additional Support:
U.S. National Oceanic and Atmospheric Administration
U.S. National Science Foundation
California Energy Commission (June 2000)