Status of CCSM2
Jeffrey T. Kiehl
CCSM Scientific Steering Committee
Chairman
Outline
• CCSM2 Description
• Status of Control Simulation
• An Overview of CCSM2 Results with
Emphasis on Variability
• CCSM2 Climate Sensitivity
• Remaining Challenges
CCSM2 Description
• CAM2:
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–
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Improved Longwave Radiation & Clouds
Prognostic Cloud Water Formulation
Changes to Convective Precip
Increased Vertical Resolution
• CCSM Ocean Model
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POP1.4 (with displaced NP into Greenland)
Anisotropic horizontal viscosity formulation
Increased Horizontal Resolution
Revised formulation of G-M Eddy scheme
CCSM2 Description
• CSIM
– New Elastic-Viscous-Plastic(EVP) ice rheology
– New Thermodynamic model, including multi-category
ice thickness scheme
• CLM
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New biogeophysics formulation
Multilayer soil water and T(z) formulation
Multilayer snow model with compaction
River runoff scheme
Status of Control Simulation
• Out to year 800, plan to continue simulation to
year 1000
• Last change made at year 350 (common physical
constants)
• No flux correction applied
• Model drifts:
– -0.04 K/century in surface temperature
– -0.07 K/century in volume avg. ocean T
– +0.0001 psu/century in volume salinity
Long Terms Trends
CCSM2 Challenges
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•
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Double ITCZ
Excessive Cold Pacific Cold Tongue
Excessive Warm Eastern Boundary Water
Cold Tropical Tropopause
Excessive High Latitude Surface
Temperatures
An Overview of CCSM2 Results
with Emphasis on
Variability
50
17
5.6
2.6
2.1
Tropical Variability
Nino3 SST Power Spectra from CCSM2 & Reanalysis
Polar Climate Variability
Seasonal Cycle Over Land
CCSM2 Climate Sensitivity
• Started 1% Increase in CO2 at year 220 of
Control
• Implies:
– 2 X CO2 at Year 70
– 4 X CO2 at Year 140
• Stopped 1% Simulation at Year 370
• Carried out Simulation fixed at 2XCO2
Current Thrusts
• Explore Higher Resolution Atmospheric
Model in CCSM2
• Continue to Improve Treatment of Cloud in
CAM
• Development of Fully Interactive Carbon
Cycle within CCSM
• Prepare for the IPCC Fourth Assessment
Acknowledgements
• Thanks to Jay Fein and Dave Bader for
their continued support
• Thanks to the Working Groups for their
commitment to the effort
• Thanks to Lydia Shiver for her support to
the CCSM effort