simulating and forecasting regional climates of the future william j. gutowski, jr. dept. geological...
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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)TRANSCRIPT
Simulating and Forecasting Simulating and Forecasting Regional Climates of the FutureRegional Climates of the Future
William J. Gutowski, Jr.William J. Gutowski, Jr.Dept. Geological & Atmospheric SciencesDept. Geological & Atmospheric Sciences
Dept. of AgronomyDept. of AgronomyIowa State UniversityIowa State University
Major contributions fromMajor contributions from::Z. Pan, R. W. Arritt, C. Anderson, F. Otieno, E. S. TakleZ. Pan, R. W. Arritt, C. Anderson, F. Otieno, E. S. Takle
Iowa State UniversityIowa State University
J. H. Christensen, O. B. ChristensenJ. H. Christensen, O. B. ChristensenDanish Meteorological Institute Danish Meteorological Institute
Copenhagen, DenmarkCopenhagen, Denmark
ISU Plant Pathology (March 2001)
• Regional Climate Models (RCMs)Regional Climate Models (RCMs)– Why?Why?– Physical BasisPhysical Basis– Simulation Considerations
• A Norm to Evaluate Projected ChangeA Norm to Evaluate Projected Change• Conclusions
OutlineOutline
ISU Plant Pathology (March 2001)
• Regional Climate Models (RCMs)Regional Climate Models (RCMs)– Why?Why?– Physical Basis– Simulation Considerations
• A Norm to Evaluate Projected Change• Conclusions
OutlineOutline
ISU Plant Pathology (March 2001)
Global Climate Models:
• nearly closed system
• complete representation
Why Regional Climate Models?Why Regional Climate Models?
Global Climate Models:
• nearly closed system
• complete representation
Why Regional Climate Models?Why Regional Climate Models?
However:
• high computing demands
• limits resolution
• many surface features unresolved (esp. human-scale)
Regional Climate Models:Regional Climate Models:
• sacrifice global coveragesacrifice global coverage
• higher resolutionhigher resolution
Why Regional Climate Models?Why Regional Climate Models?
Global Global Model Model ResolutionResolution
X = 250 kmX = 250 km
contours every 250 m
TERRAIN HEIGHT
contours every 250 m
TERRAIN HEIGHT
Regional Regional Model Model ResolutionResolution
X = 50 kmX = 50 km
contours every 250 m
FutureFuture Model Model Resolution?Resolution?
X = 10 kmX = 10 km
TERRAIN HEIGHT
• Regional Climate Models (RCMs)Regional Climate Models (RCMs)– Why?Why?– Physical Basis– Simulation Considerations
• A Norm to Evaluate Projected Change• Conclusions
OutlineOutline
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”
ΔMΔt =?
Conservation of “M”
ΔMΔt ≠0
Source/sink≠0
Conservation of “M”
ΔMΔt ≠0
Conservation of “M”
ΔMΔt ≠0
Conservation of “M”
Source/sink≠0ΔMΔt ≠0
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 exchange Radiation 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
Evapotranspiration Precipitation
MoistureIn/Out
Δ Moisture( )Δt ≠0
EP P
Q Q
R
Water CycleWater Cycle
E
E
Water CycleWater Cycle
Heat absorbedHeat absorbed
Heat releasedHeat released
Water is thus a primaryWater is thus a primary form of heat transportform of heat transport
heat absorbed when evaporates heat absorbed when evaporates released when water condensesreleased when water condenses largest individual source of energy largest individual source of energy for the atmospherefor the atmosphere
Water CycleWater Cycle
Radiation absorbed by water & re-emittedRadiation absorbed by water & re-emitted
Water is thus a primaryWater is thus a primary form of heat transportform of heat transport
heat absorbed when evaporates heat absorbed when evaporates released when water condensesreleased when water condenses largest individual source of energy largest individual source of energy for the atmospherefor the atmosphere
andand greenhouse gas greenhouse gas ~ transparent to solar~ transparent to solar absorbs/emits infraredabsorbs/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?Why?– Physical BasisPhysical Basis– Simulation Considerations
• A Norm to Evaluate Projected Change• Conclusions
OutlineOutline
ISU Plant Pathology (March 2001)
EvapotranspirationEvapotranspiration
EvapotranspirationEvapotranspirationE ~ - CW{eair-esat(Ts)}
CW = CW(atmos.)
but also
CW = CW(physiology)
soil moisture
CW leaf temp.
sunlight
CO2 level
EvapotranspirationEvapotranspirationE ~ - CW{eair-esat(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
PolarStereographic
True at 90o
RCM Horizontal Grid
Lambert Conformal
True at, e.g.,30o and 60o
RCM Horizontal Grid
Mercator
True at 0o
RCM Horizontal Grid
Forcing Frame:for lateral
boundary conditions“free” interior
RCM Horizontal Grid
EP
Q
R
Earth Climate SystemEarth Climate System
E
GlobalRegional Regional Regional Regional
Microscale Microscale Microscale Microscale Microscale Microscale Microscale Microscale Microscale
Plan
t ACrop BCrop A
Ins e
c t A
Soil
Path
ogen
B
Air-TransportedPathogen A
Field Field Field Field Field Field Field Field Field Field
Regional Regional Regional RegionalContinental
Hydrology, Soil Microbiology, Soil Biochemistry
Soil AH2O, temperature,
nutrients, microbes, soil carbon, trace chemicals
Soil AH2O, temperature,
nutrients, microbes, soil carbon, trace chemicals
Soil BH2O, temperature,
nutrients, microbes, soil carbon, trace chemicals
Soil BH2O, temperature,
nutrients, microbes, soil carbon, trace chemicals
Soil CH2O, temperature,
nutrients, microbes, soil carbon, trace chemicals
Scales of Climate
Scales of Landforms
Soil
Path
ogen
D
Plan
t B
Ins e
c t B
Air-TransportedPathogen B
Human Influences
Management Management
Che
mic
als
Eros
ion
Che
mic
als
Surf
ace
s lop
e, I R
Rad
i at i o
n, E
vapo
rat io
n, B
ioge
oche
mi c
als
Detritus
Particulate Deposition, Precipitation, Solar R
adiation, IR
Microclimate A
Sola
r, IR
, win
d,C
O2,
CO
, NO
x,SO
2, H
2O, t
empe
ratu
re,
trace
gas
es, s
hadi
ng,
parti
cula
te m
atte
r
Sola
r, IR
, win
d,C
O2,
CO
, NO
x,SO
2, H
2O, t
empe
ratu
re,
trace
gas
es, s
hadi
ng,
parti
cula
te m
atte
r
Sola
r, IR
, win
d,C
O2,
CO
, NO
x,SO
2, H
2O, t
empe
ratu
re,
trace
gas
es, s
hadi
ng,
parti
cula
te m
atte
r
Microclimate CMicroclimate B
ChemicalsChemicals
• Regional Climate Models (RCMs)Regional Climate Models (RCMs)– Why?Why?– Physical BasisPhysical Basis– Simulation Considerations
• A Norm to Evaluate Projected ChangeA Norm to Evaluate Projected Change• Conclusions
OutlineOutline
ISU Plant Pathology (March 2001)
Simulate decades/centuries into futureSimulate decades/centuries into future
How are projections verified?How are projections verified?
Projections of Future Climate
Simulate decades/centuries into futureSimulate decades/centuries into future
How are projections verified?How are projections verified?• Accuracy of present climate simulation?Accuracy of present climate simulation?
Projections of Future Climate
Simulate decades/centuries into futureSimulate decades/centuries into future
How are projections verified?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 futureSimulate decades/centuries into future
How are projections verified?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 futureSimulate decades/centuries into future
How are projections verified?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 SimulationsCross-Compare Multiple Simulations
Model Observed GCM-control GCM-Scenario
RegCM2 NCEPReanalysis(1979-1988)
HadleyCentre(~1990’s)
HadleyCentre(2040-2050)
HIRHAM(DMI)
“ “ “
Simulation DomainSimulation Domain
Reanalysis
HadCMCont/Scen
RegCM2
HIRHAM
Possible Comparisons?
OBS
HadCMCont/Scen
Driving Differences
Definition of Biases
Reanalysis RegCM2 OBS
RCM (performance) bias
Reanalysis RegCM2
HIRHAM
Inter-modelbias
Definition of Biases
Reanalysis
HadCM
RegCM2
RegCM2
Definition of Biases
Forcingbias
HadCM
RegCM2
HadCM
Definition of Biases
G-R nestingbias
HadCM control
HadCMscenario
RegCM2
RegCM2
Climate Change
Change
Climate Change
P
Control Scenario
Change
Climate Change
P
Control Scenario
ChangeMax Bias
Analysis Regions
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
winter
spring
summer
autumn
SE
HIRHAM
0
1
2
3
4
5
6
7
PNW CA MW NE SE
Region
winterspringsummerautumn
0 1 2
0 1 2
0 1 2
0
100
200
300
400
500
AUG OCT DEC FEB APR JUN
ReGCM2 Sierra
NCEPHCONTHSCEN
Month
0
100
200
300
400
500
AUG OCT DEC FEB APR JUN
HIRHAM Sierra
NCEPHCONTHSCEN
Month
Annual Snow Cycle
• Regional Climate Models (RCMs)Regional Climate Models (RCMs)– Why?Why?– Physical BasisPhysical Basis– Simulation Considerations
• A Norm to Evaluate Projected ChangeA Norm to Evaluate Projected Change• Conclusions
OutlineOutline
ISU Plant Pathology (March 2001)
ISU Plant Pathology (March 2001)
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% poor
** = Subject to quality of driving GCM!
ISU Plant Pathology (March 2001)
• Ratio of climate change to biases is especially Ratio of climate change to biases is especially large in the California regionlarge in the California region
• Differences between RCM and GCM imply room Differences between RCM and GCM imply room for RCMs to add value to GCM simulationsfor RCMs to add value to GCM simulations
• Regional warming signal is less robust than Regional warming signal is less robust than precipitation changeprecipitation change
• Future warming projection has large inter-model Future warming projection has large inter-model differencesdifferences
Conclusions
Acknowledgments
Primary Funding: Electric Power Research Institute (EPRI)
Additional Support: U.S. National Oceanic and Atmospheric AdministrationU.S. National Science Foundation
ISU Plant Pathology (March 2001)
EXTRA SLIDES
Southeast U.S.
-3
-2
-1
0
1
2
3
4
win spr sum aut anu
season
RCM bias forcing biasintermodel bias G-R nesting biasclimate change
Prec
ip [m
m/d
ay]
2 3
45
1
Analysis Points
0
5
10
15
20
OBS-1 NC-1 HCont-1 HScen-1
October - March (RegCM2)
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-2 NC-2 HCont-2 HScen-2
April-September (RegCM2)
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]
Precipitation RegionsPrecipitation Regions
UpperMiss.
observation
0
200
400
600
800
1000
79 80 81 82 83 84 85 86 87 88
Year
WinterSpringSummerAutumn
Range: 600 - 970 mm
RegCM2
0
200
400
600
800
1000
79 80 81 82 83 84 85 86 87 88Year
WinterSpringSummerAutumn
Range: 650 - 850 mm
HIRHAM
0
200
400
600
800
1000
79 80 81 82 83 84 85 86 87 88
Year
WinterSpringSummerAutumn
Range: 590 - 870 mm
Energy Balance for EarthEnergy Balance for Earth
Energy Balance for EarthEnergy Balance for Earth
Planetary Planetary Albedo Albedo
Energy Balance for EarthEnergy Balance for Earth
Energy Balance for EarthEnergy Balance for Earth
Conservation of MomentumConservation of Momentum~ Newton’s Second Law ~~ Newton’s Second Law ~
Forces/mass:Forces/mass: gravitygravity pressure gradientpressure gradient frictionfriction
Conservation of MomentumConservation of Momentum~ Newton’s Second Law ~~ Newton’s Second Law ~
Rotating Frame
r Ω
r R
X
dr V 3dt
= (Forces/ mass)∑−2
r Ω × r
V 3 +r Ω 2 r
R
Conservation of MomentumConservation of Momentum~ Newton’s Second Law ~~ Newton’s Second Law ~
Rotating Frame
dudt
−uvtanφa
+uwa
=−1ρ
∂p∂x
+2Ωvsinφ−2Ωwcosφ+Frx
Conservation of MomentumConservation of Momentum~ Newton’s Second Law ~~ Newton’s Second Law ~
Sphere, Rotating Frame
dvdt
−u2 tanφa
+vwa
=−1ρ
∂p∂y
−2Ωusinφ +Fry
dwdt
−u2 +v2
a=−1
ρ∂p∂z
+2Ωucosφ −g+Frz
rotation of direction