Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Ten-Year Simulations of U.S. Regional Climate Z. Pan, W. J. Gutowski, Jr., R. W. Arritt, E. S. Takle, F. Otieno, C. Anderson, M. Segal Iowa State University J. H. Christensen, O. B. Christensen Danish Meteorological Institute Copenhagen, Denmark START Temperate East Asia Regional Center (February 2000) Outline Overview Comparison with Observations Precipitation Tmin, Tmax Biases as norms for evaluating climate change Precipitation Tmin, Tmax Conclusions START Temperate East Asia Regional Center (February 2000) Outline Overview START Temperate East Asia Regional Center (February 2000) Simulations Model Observed RegCM2 NCEP Hadley Reanalysis Centre (1979-1988) (~1990’s) HIRHAM (DMI) “ GCM-control GCMScenario “ Hadley Centre (2040-2050) “ Domain Purpose Evaluate RCM performance Compare RCM and GCM projections Assess U.S. regional climate change uncertainty Outline Overview Comparison with Observations Precipitation Tmin, Tmax START Temperate East Asia Regional Center (February 2000) RegCM2 Bias VEMAP JAN JUL -4 -2 0 +2 +4 +6 [mm/d] Self-Organizing Maps Set of maps • Trained to distribution of data • Give 2-D projection of higher order map space • Show characteristic data structures • Are approximately continuous “Robert Johnson” box: (31-35 N, 85-90 W) Precipitation Regions Upper Miss. Range: 600 - 970 mm Range: 650 - 850 mm Range: 590 - 870 mm Tmin/Tmax Problem: Model elevations different from observing stations O O O O O Tmin/Tmax Problem: Model elevations different from observing stations O O O O O “Solution”: Interpolate to common elevation using dT/dz = - 6.5 K/km (common = real world @ 1/2 deg) 10 Year Mean Maximum Temperature - RegCM2 -12.5 -2.5 +2.5 +12.5 +22.5 [C] 10 Year Mean Maximum Temperature - DMI -12.5 -2.5 +2.5 +12.5 +22.5 [C] 10 Year Mean Minimum Temperature - RegCM2 -12.5 -2.5 +2.5 +12.5 +22.5 [C] 10 Year Mean Minimum Temperature - DMI -12.5 -2.5 +2.5 +12.5 +22.5 [C] Outline Overview Comparison with Observations Precipitation Tmin, Tmax Biases as norms for evaluating climate change Precipitation Tmin, Tmax START Temperate East Asia Regional Center (February 2000) Possible Comparisons? Reanalysis HadCM Cont/Scen Driving RegCM2 OBS HIRHAM HadCM Cont/Scen 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 RegCM2 HadCM G-R nesting bias HadCM Climate Change HadCM control RegCM2 Change HadCM scenario RegCM2 Climate Change P Change Control Scenario Climate Change P Max Bias Control Change Scenario Analysis Regions Definitions Seasonal-regional biases PRCM 1 N m o Pi Pi N i1 Po, Pm are observed, model precipitation N is total grids in the region Climate change ratio Rchng Pchng Max ( PRCM , Pforc, Pitmd ) RegCM2 7 Rchng 6 winter spring summer autumn 5 4 3 2 1 0 PNW CA MW NE Region Rchng Pchng Max ( PRCM , Pforc, Pitmd ) NS HIRHAM 7 6 winter spring summer autumn Rchng 5 4 3 2 1 0 PNW CA MW Region NE SE Include here Tmin/max transparencies Degree-days Wind power Outline Overview Comparison with Observations Precipitation Tmin, Tmax Biases as norms for evaluating climate change Precipitation Tmin, Tmax Conclusions START Temperate East Asia Regional Center (February 2000) Conclusions RegCM2 simulates broad-scale regional features fairly well. Interannual variability in RegCM2 (and HIRHAM) is less than observed. Specific regions and seasons pose special challenge to RegCM2, e.g., south-central US Timing of events good Magnitude poor Moisture transport problem? START Temperate East Asia Regional Center (February 2000) Conclusions Climate change is 1-3 times larger than biases in most seasons and regions summer ratios are always less than 1 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 START Temperate East Asia Regional Center (February 2000) Conclusions Regional warming signal is less robust than precipitation change Future warming projection has large inter-model differences Warming greater for Tmin than Tmax Warming greater for winter than summer START Temperate East Asia Regional Center (February 2000) Acknowledgments Primary Funding: Electric Power Research Institute (EPRI) Additional Support: U.S. National Oceanic and Atmospheric Administration U.S. National Science Foundation START Temperate East Asia Regional Center (February 2000) EXTRA SLIDES Definition of Biases RCM (performance) bias - difference between reanalysis-driven RCM simulation and observations forcing bias - difference between runs driven by GCM control climate and driven by reanalysis inter-model bias - difference between runs from different RCMs (HIRHAM minus RegCM2), both driven by reanalysis G-R nesting bias – difference between GCM run and RCM run driven by GCM output, both for current climate.