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: – Improved Longwave Radiation & Clouds – Prognostic Cloud Water Formulation – Changes to Convective Precip – Increased Vertical Resolution • CCSM Ocean Model – 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 – 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 • 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 CO 2 Control at year 220 of • Implies: – 2 X – 4 X CO 2 CO 2 at Year 70 at Year 140 • Stopped 1% Simulation at Year 370 • Carried out Simulation fixed at 2 X CO 2

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