eric salathé climate impacts group (jisao/sma) university of washington constructing regional...
Post on 21-Dec-2015
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Eric SalathéClimate Impacts Group
(JISAO/SMA)University of Washington
Constructing regional climate change scenarios
What do Global Models do?
Simulate the global circulation patterns
Can be derived from observations for verification
Precipitation and Temperature is what would occur with global circulation and smooth Earth Does not correspond to observations
Local Scaling
Effect of Wind PatternsWind from South Wind from Southwest
WeakRainshadow
StrongRainshadow
Monthly Flow in Yakima River
Downscaled ECHAM4 IPCC A2-121.7 47.5 (Snoqualmie Pass)
€
PΔ (t) = Phistoric(t)׈ P CC
ˆ P CTR
=σ historic(t)׈ P historic
ˆ P CC
ˆ P CTR
€
PDS ( t) = Pcc(t)׈ P historic
ˆ P CTR
= σ CC (t)׈ P historic
ˆ P CC
ˆ P CTR
“Delta” method -- scale the historic data by the climate-change signal:
Statistical downscaling,-- remove bias in climate-changePrecipitation using the historic data:
The choice is where the time-series characteristicsare taken from:History or Model?
Percent of years with precipitation In bottom 20% of Historic Range
What is the Climate Signal?
Regional Climate Models
Probably not best primary tool for impact studies
Several research issues1. “Second Order” effects
Cold air outbreaks marine layer moves inland.
2. Orographic precipitation response to warming
3. ENSO response
Comparison of RCM and Statistical DownscalingOf Reanalysis GCM
Arbitrary point onCascade Crest
Regional Climate Models
Probably not best primary tool for impact studies
Several research issues1. “Second Order” effects
Cold air outbreaks marine layer moves inland.
2. Orographic precipitation response to warming
3. ENSO response
Summary
1/8-degree P, Tmin, Tmax for IPCC scenarios
What information should we take from models?
What information should we take from historic
record?
What can we (should we) learn from regional
climate models?