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New Horizons in Paleoclimatol ogy Toby Ault 5.6.2008
New Horizons inPaleoclimatology
Toby Ault5.6.2008
Overview:
Proxy-model integration Experiment design Results Future work
Overview:
Proxy-model integration Experiment design Results Future work
Overview:
Proxy-model integration Experiment design Results Future work
Overview:
Proxy-model integration Experiment design Results Future work
Overview:
Proxy-model integration Experiment design Results Future work
Proxy-Model Integration
10’s of km
GCM Data: Proxy Data:
100’s of km
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Image from: http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch11.pdf
1°x1°(~111 km)
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PRISM mean precip. (mm/day)
http://www.prism.oregonstate.edu/products/viewer.phtml?file=/pub/prism/us/graphics/ppt/2000-2009/us_ppt_2006.08.png&year=2006&vartype=ppt&month=08&status=final&zoom=yes
Observational Monsoon
0.5˚x 0.5˚ JJA mean precip. (mm/day)*Mitchell, T. D., and P. D. Jones (2005), An improved method of constructing a database of monthly climate observations and associated high-resolution grids, International Journal of Climatology, 25(6), 693-712.
CCSM3’s Monsoon
JAS mean precip. (mm/day)
CCSM3’s Monsoon
JAS mean precip. (mm/day)
What about the future?
*Joellen Russell, Pers. comm.
GFDL - Weaker
CCSM - No change
UKMO - Stronger
*Joellen Russell, Pers. comm.
GFDL - Weaker
CCSM - No change
UKMO - Stronger
No good consensus…Absent in other models…
Turn to proxies!
Mid-Holocene climate
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http://geochange.er.usgs.gov/sw/impacts/biology/pastclim/
Proxies in N. America
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http://www.swaebr.org/images/Packrat.jpg
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Wetter summers…OR
…drier winters!
Playa Lakes:Occasionally filled during
Mid-Holocene
Likely monsoon related…
http://en.wikipedia.org/wiki/Playa
Speleothems:Stronger Monsoon
Connection to North AtlanticITCZ shifted northward?
Modeling 6ka climates
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PMIP(Paleoclimate Model Intercomparison Project)
Mean JJA precipitation for CCSM 6ka simulationhttp://www.ncdc.noaa.gov/paleo/modelvis.html
Harrison et al., 2003
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CCSM3-JJA: 6ka-0ka (mm/day)
Harrison et al., 2003
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CCSM3-JJA: 6ka-0ka (mm/day)
No Change?
10’s of km
GCM Data: Proxy Data:
100’s of km
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Image from: http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch11.pdf
10’s of km
GCM Data: Proxy Data:
100’s of km
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Can regional downscaling bridge this gap?
Experiment Design
Model: WRFNesting: NonePhysics: DefaultsX-domain: 119˚W to 110˚WY-domain: 20˚N to 34˚NResolution: ~30kmTime: Aug. 2-25, 2006T: 3hrs
Boundary Conditions:NCEP/NCAR Reanalysis2.5˚x 2.5˚ resolution
Results
Means
Precipitation (mm/day)
NNRP WRF
Variance
Precipitation variance (mm/day)2
NNRP WRF
Smaller scale
Better representationof mechanisms
Future Work
1. Comparison with observations
2. Better analysis of dynamics
3. Cumulus parameterization scheme
4. Downscaling modern CCSM3 runs
5. Paleoclimate downscaling
1. Comparison with observations
2. Better analysis of dynamics
3. Cumulus parameterization scheme
4. Downscaling modern CCSM3 runs
5. Paleoclimate downscaling
1. Comparison with observations
2. Better analysis of dynamics
3. Cumulus parameterization scheme
4. Downscaling modern CCSM3 runs
5. Paleoclimate downscaling
1. Comparison with observations
2. Better analysis of dynamics
3. Cumulus parameterization scheme
4. Downscaling modern CCSM3 runs
5. Paleoclimate downscaling
1. Comparison with observations
2. Better analysis of dynamics
3. Cumulus parameterization scheme
4. Downscaling modern CCSM3 runs
5. Paleoclimate downscaling
1. Comparison with observations
2. Better analysis of dynamics
3. Cumulus parameterization scheme
4. Downscaling modern CCSM3 runs
5. Paleoclimate downscaling
Acknowledgements:
Jason Criscio, Andy Penny, and CCIT - THANKS!
