Simulating and Forecasting Regional Climates of the Future William J. Gutowski, Jr. Dept. Geological & Atmospheric Sciences Dept. of Agronomy Iowa State University Major contributions from: Z. Pan, R. W. Arritt, C. Anderson, F. Otieno, E. S. Takle Iowa State University J. H. Christensen, O. B. Christensen Danish Meteorological Institute Copenhagen, Denmark ISU Plant Pathology(March 2001)

Regional Climate Models (RCMs)Regional Climate Models (RCMs) –Why? –Physical Basis –Simulation Considerations A Norm to Evaluate Projected ChangeA Norm to Evaluate Projected Change Conclusions Outline ISU Plant Pathology(March 2001)

Regional Climate Models (RCMs)Regional Climate Models (RCMs) –Why? –Physical Basis –Simulation Considerations A Norm to Evaluate Projected Change Conclusions Outline ISU Plant Pathology(March 2001)

Global Climate Models: nearly closed system complete representation Why Regional Climate Models?

Global Climate Models: nearly closed system complete representation Why Regional Climate Models? However: high computing demands limits resolution many surface features unresolved (esp. human-scale)

Regional Climate Models: sacrifice global coverage sacrifice global coverage higher resolution higher resolution Why Regional Climate Models?

Global Model Resolution  X = 250 km contours every 250 m TERRAIN HEIGHT

contours every 250 m TERRAIN HEIGHT Regional Model Resolution  X = 50 km

contours every 250 m Future Model Resolution?  X = 10 km TERRAIN HEIGHT

Regional Climate Models (RCMs)Regional Climate Models (RCMs) –Why? –Physical Basis –Simulation Considerations A Norm to Evaluate Projected Change Conclusions Outline ISU Plant Pathology(March 2001)

1. Conservation of Thermodynamic Energy (First Law of Thermodynamics) 2. Conservation of Momentum (Newton’s Second Law) 3. Conservation of Mass RCM Foundation: Conservation Laws of Physics

Conservation of “M”

Conservation of “M”

Conservation of “M”

Conservation of “M”

Conservation of “M”

1. Conservation of Thermodynamic Energy (First Law of Thermodynamics): Heat input =  internal energy) + (work done) RCM Foundation: Conservation Laws of Physics Transport and accumulation by circulation

“Contact” heat exchangeRadiation to/from surface Heat Source/Sink Condensation Radiation to/from space

2. Conservation of Momentum (Newton’s Second Law):  wind)/  time) =  forces) RCM Foundation: Conservation Laws of Physics

3. Conservation of Mass: Special constituent - water RCM Foundation: Conservation Laws of Physics

EvapotranspirationPrecipitation Moisture In/Out

E P P Q Q R Water Cycle E

E Heat absorbed Heat released

Water is thus a primary  form of heat transport  heat absorbed when evaporates  released when water condenses  largest individual source of energy for the atmosphere for the atmosphere

Water Cycle Radiation absorbed by water & re-emitted

Water is thus a primary  form of heat transport  heat absorbed when evaporates  released when water condenses  largest individual source of energy for the atmosphere for the atmosphere  and greenhouse gas  ~ transparent to solar  absorbs/emits infrared

1. Conservation of Thermodynamic Energy (First Law of Thermodynamics) 2. Conservation of Momentum (Newton’s Second Law) 3. Conservation of Mass Plus: Ideal Gas Law RCM Foundation: Fundamental Laws of Physics

Regional Climate Models (RCMs)Regional Climate Models (RCMs) –Why? –Physical Basis –Simulation Considerations A Norm to Evaluate Projected Change Conclusions Outline ISU Plant Pathology(March 2001)

Evapotranspiration

Evapotranspiration E ~ - C W {e air -e sat (Ts)}

C W = C W (atmos.) but also C W = C W (physiology) soil moisture C W  leaf temp. sunlight CO 2 level Evapotranspiration E ~ - C W {e air -e sat (Ts)}

RCM Horizontal Grid I J (1,1) (IMAX,JMAX)

RCM Horizontal Grid I J (1,1) (IMAX,JMAX)

How does a “flat” grid... RCM Horizontal Grid

How does a “flat” grid......represent part of the spherical earth? ? RCM Horizontal Grid

By projection to a flat plane RCM Horizontal Grid

Polar Stereographic True at 90 o RCM Horizontal Grid

Lambert Conformal True at, e.g., 30 o and 60 o RCM Horizontal Grid

Mercator True at 0 o RCM Horizontal Grid

Forcing Frame: for lateral boundary conditions “free” interior RCM Horizontal Grid

E P Q R Earth Climate System E

Global RegionalRegionalRegionalRegional MicroscaleMicroscaleMicroscaleMicroscaleMicroscaleMicroscaleMicroscaleMicroscaleMicroscale Plant A Crop BCrop A Insect A Soil Pathogen B Air-Transported Pathogen A FieldFieldFieldFieldFieldFieldFieldFieldFieldField RegionalRegionalRegionalRegional Continental Hydrology, Soil Microbiology, Soil Biochemistry Soil A H 2 O, temperature, nutrients, microbes, soil carbon, trace chemicals Soil A H 2 O, temperature, nutrients, microbes, soil carbon, trace chemicals Soil B H 2 O, temperature, nutrients, microbes, soil carbon, trace chemicals Soil B H 2 O, temperature, nutrients, microbes, soil carbon, trace chemicals Soil C H 2 O, temperature, nutrients, microbes, soil carbon, trace chemicals Scales of Climate Scales of Landforms Soil Pathogen D Plant B Insect B Air-Transported Pathogen B Human Influences Management Chemical s Erosion Chemical s Surface slope, IR Radiation, Evaporation, Biogeochemicals Detritus Particulate Deposition, Precipitation, Solar Radiation, IR Microclimate A Solar, IR, wind, CO 2, CO, NO x,SO 2, H 2 O, temperature, trace gases, shading, particulate matter Solar, IR, wind, CO 2, CO, NO x,SO 2, H 2 O, temperature, trace gases, shading, particulate matter Solar, IR, wind, CO 2, CO, NO x,SO 2, H 2 O, temperature, trace gases, shading, particulate matter Microclimate CMicroclimate B Chemical s

Regional Climate Models (RCMs)Regional Climate Models (RCMs) –Why? –Physical Basis –Simulation Considerations A Norm to Evaluate Projected ChangeA Norm to Evaluate Projected Change Conclusions Outline ISU Plant Pathology(March 2001)

 Simulate decades/centuries into future  How are projections verified? Projections of Future Climate

 Simulate decades/centuries into future  How are projections verified? Accuracy of present climate simulation? Accuracy of present climate simulation? Projections of Future Climate

 Simulate decades/centuries into future  How are projections verified? Accuracy of present climate simulation? Accuracy of present climate simulation? Accuracy of paleoclimate simulation? Accuracy of paleoclimate simulation? Projections of Future Climate

 Simulate decades/centuries into future  How are projections verified? Accuracy of present climate simulation? Accuracy of present climate simulation? Accuracy of paleoclimate simulation? Accuracy of paleoclimate simulation? Alternative … Alternative … Projections of Future Climate

 Simulate decades/centuries into future  How are projections verified? Accuracy of present climate simulation? Accuracy of present climate simulation? Accuracy of paleoclimate simulation? Accuracy of paleoclimate simulation? Alternative … Alternative … Projections of Future Climate

Cross-Compare Multiple Simulations

Simulation Domain

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

Definition of Biases ReanalysisRegCM2OBS RCM (performance) bias

ReanalysisRegCM2 HIRHAM Inter-model bias Definition of Biases

Reanalysis HadCM RegCM2 Definition of Biases Forcing bias

HadCM RegCM2 HadCM Definition of Biases G-R nesting bias

HadCM control HadCM scenario RegCM2 Climate Change Change

Climate Change P Control Scenario Change

Climate Change P Control Scenario Change Max Bias

Analysis Regions

SE

0 1 2

Annual Snow Cycle

Regional Climate Models (RCMs)Regional Climate Models (RCMs) –Why? –Physical Basis –Simulation Considerations A Norm to Evaluate Projected ChangeA Norm to Evaluate Projected Change Conclusions Outline ISU Plant Pathology(March 2001)

** = Subject to quality of driving GCM!

ISU Plant Pathology(March 2001) Ratio of climate change to biases is especially large in the California regionRatio 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 simulationsDifferences between RCM and GCM imply room for RCMs to add value to GCM simulations Regional warming signal is less robust than precipitation changeRegional warming signal is less robust than precipitation change Future warming projection has large inter-model differencesFuture warming projection has large inter-model differences Conclusions

Acknowledgments  Primary Funding: Electric Power Research Institute (EPRI)  Additional Support: U.S. National Oceanic and Atmospheric Administration U.S. National Science Foundation ISU Plant Pathology(March 2001)

EXTRA SLIDES

Precip [mm/day]

Analysis Points

Precipitation Regions Upper Miss.

Range: mm

Range: mm

Range: mm

Energy Balance for Earth

Planetary Albedo

Energy Balance for Earth

Conservation of Momentum ~ Newton’s Second Law ~ Forces/mass: ä gravity ä pressure gradient ä friction

Conservation of Momentum ~ Newton’s Second Law ~ Rotating Frame X

Conservation of Momentum ~ Newton’s Second Law ~ Rotating Frame

Conservation of Momentum ~ Newton’s Second Law ~ Sphere, Rotating Frame rotation of direction