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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.
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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)
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)
Outline • Overview - Regional Climate Simulation California Energy Commission (June 2000)
DX = 250 km contours every 250 m
DX = 50 km contours every 250 m
DX = 10 km contours every 250 m
Purpose • Evaluate RCM performance • Compare RCM and GCM projections • Assess U.S. regional climate change uncertainty
Outline • Overview - Regional Climate Simulation • Biases as norms for evaluating climate change • Precipitation • Tmin, Tmax California Energy Commission (June 2000)
Possible Comparisons? Reanalysis RegCM2 OBS HadCM Cont/Scen HIRHAM HadCM Cont/Scen Driving Differences
Definition of Biases Reanalysis RegCM2 OBS RCM (performance) bias
Definition of Biases Reanalysis RegCM2 Inter-model bias HIRHAM
Definition of Biases Reanalysis RegCM2 Forcing bias HadCM RegCM2
Definition of Biases G-R nesting bias RegCM2 HadCM HadCM
Climate Change HadCM control RegCM2 Change HadCM scenario RegCM2
Climate Change P Change Control Scenario
Climate Change P Change Max Bias Control Scenario
Seasonal-regional biases Definitions Po, Pm are observed, model precipitation N is total grids in the region Climate change ratio
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)
Analysis Points 1 2 3 4 5
CA Temp Biases: Tmax - small, mixed Tmax - slightly cool Tmin - warm (few oC) Tmin - small, mixed
Other Models? PIRCS OBS (1993) (1993) [mm]
PIRCS (1993) [mm]
PIRCS (1993) [mm]
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)
** = Subject to quality of driving GCM! California Energy Commission (June 2000)
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)
Acknowledgments • Primary Funding: Electric Power Research Institute (EPRI) • Additional Support: U.S. National Oceanic and Atmospheric Administration U.S. National Science Foundation California Energy Commission (June 2000)