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The Community Climate System Model

The Community Climate System Model. Bill Collins Chair, CCSM Scientific Steering Committee National Center for Atmospheric Research Boulder, Colorado. Applications of CCSM Development of new version of CCSM Features of CCSM simulations Future improvements in CCSM

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The Community Climate System Model

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  1. The Community Climate System Model Bill Collins Chair, CCSM Scientific Steering Committee National Center for Atmospheric Research Boulder, Colorado • Applications of CCSM • Development of new version of CCSM • Features of CCSM simulations • Future improvements in CCSM • Computational demands for new science CAS2K3 Meeting, Annecy September 8-11, 2003

  2. Structure of CCSM Atmosphere (CAM) Land (CLM) Coupler (CPL) Sea Ice (CSIM) Ocean (POP) CAS2K3 Meeting, Annecy September 8-11, 2003

  3. Component Models in CCSM • Atmosphere • Multiple dynamical cores: SLD, Eulerian, & Finite Volume • Generalized 2D decomposition of grid • Resolutions with most heritage: T31, T42, and T85 (L26) • Ocean • Derivative of LANL Parallel Ocean Program • Grid: spherical in S. hemisphere, orthogonal curvilinear in N. hemisphere • Standard resolution: 320 x 384 (L40) • Land Surface • Superset of NCAR LSM and Georgia Tech BATS • Same horizontal resolution as atmosphere • 10 layers for soil, up to 5 for snowpack • Sea Ice • Up to 5 categories of sea-ice thickness CAS2K3 Meeting, Annecy September 8-11, 2003

  4. Organization of CCSM Project CAS2K3 Meeting, Annecy September 8-11, 2003

  5. Utilization of CCSM CAS2K3 Meeting, Annecy September 8-11, 2003

  6. Simulation of Recent Climate CAS2K3 Meeting, Annecy September 8-11, 2003

  7. CCSM2 – Holocene Climate For the mid-Holocene, lake levels, plant macrofossil, and pollen data indicate a greener Sahara. Annual Precipitation Change 8.5 ka minus Present Kohfield and Harrison, 2000 • PMIP models underestimated both the north-ward shift and magnitude of the precipitation increase required to maintain lakes and vegetation. • CCSM2 more realistically simulates rainfall increases between 20-25°N latitude • CCSM2 still underestimates needed rainfall along the Mediterranean and in South Africa. Collaborators: PARCS, PMIP CCSM2 CAS2K3 Meeting, Annecy September 8-11, 2003 mm/year

  8. CCSM2 – Last Interglacial Climate Camp Century  GRIP  Renland   Dye 3 • Terrestrial data sites warmed rapidly and early; most by 4-6oC. • Greenland ice cap melted except for summit. JJA Surface Temperature 130 ka minus Present • CCSM2 forced with anomalous seasonal solar insolation associated with orbital changes warms the Arctic climate. • For summer, Arctic sea ice decreases significantly and Greenland warms by 1-5oC. CAS2K3 Meeting, Annecy September 8-11, 2003 CCSM2

  9. CCSM2 Improvements for Paleoclimate • River runoff scheme • New sea-ice model • Free surface ocean & prognostic cloud water in the atmosphere • Grid and ocean/land mapping capability for any past time period Bathymetry and land mask editing tool eCubed. [John Davis and Rick Smith (LLNL); Walter Voit (UT Dallas)] CAS2K3 Meeting, Annecy September 8-11, 2003

  10. El Nino Simulations for Current Climate CAS2K3 Meeting, Annecy September 8-11, 2003

  11. Predicting Co-evolution of CO2 and Climate Atmospheric GCM Prognostic CO2 Fossil Fuel CO2 Biophysics + BGC Ocean GCM + BGC CAS2K3 Meeting, Annecy September 8-11, 2003

  12. Ongoing Development of CCSM CSM 1.0 June 1996 New ocean, land, sea-ice models New physics in atmosphere CCSM 2.0 May 2002 New physics in all models CCSM 3.0 Winter 2003 CAS2K3 Meeting, Annecy September 8-11, 2003

  13. Main Model Biases in CCSM2 • Double ITCZ and extended cold tongue • Cold tongue mitigated in new POP, double ITCZ in new CAM • Overestimation of winter land surface temperatures • Bias largely eliminated in new CLM and CAM • Underestimation of tropical tropopause temperatures • Bias reduced in new CAM • Erroneous cloud response to SST changes • Signs and pattern of response corrected in new CAM • Errors in E. Pacific surface energy budget • Overestimation of insolation larger in prototype • Underestimation of tropical variability • Underestimation still present CAS2K3 Meeting, Annecy September 8-11, 2003

  14. Double ITCZ CAS2K3 Meeting, Annecy September 8-11, 2003

  15. Winter Land Surface Temperatures CAS2K3 Meeting, Annecy September 8-11, 2003

  16. Tropical Tropopause Temperatures CAS2K3 Meeting, Annecy September 8-11, 2003

  17. Cloud Forcing Response to Tropical SSTs CAS2K3 Meeting, Annecy September 8-11, 2003

  18. East Pacific Surface Energy Budget CAS2K3 Meeting, Annecy September 8-11, 2003

  19. Tropical Variability CAS2K3 Meeting, Annecy September 8-11, 2003

  20. Ocean Model Changes for CCSM 3.0 • KPP boundary layer • Double Diffusion • Solar Absorption (Chlorophyll) • Ideal Age and Passive Tracer Infrastructure • Ocean Currents in Air-Sea Fluxes CAS2K3 Meeting, Annecy September 8-11, 2003

  21. Mixed Layer Depths CONTROL All Physics + Numerical MODS Jan July CAS2K3 Meeting, Annecy September 8-11, 2003

  22. SST Signature of Solar Absorption CAS2K3 Meeting, Annecy September 8-11, 2003

  23. SST Signature of All Ocean Modifications CAS2K3 Meeting, Annecy September 8-11, 2003

  24. Momentum Flux Wind Speed 0 ua Land Model Working Group Goal For CCSM2: state-of-the-art model with focus on biogeophysics, hydrology, river routing Goal For Next Few Years: Natural and human-mediated changes in land cover and ecosystem functions and their effects on climate, water resources, and biogeochemistry Process: Continue to develop and improve existing physical parameterizations in the model while adding new biological and chemical process Biogeophysics Hydrology Sensible Heat Flux Latent Heat Flux Photosynthesis Precipitation Diffuse Solar Radiation Longwave Radiation Evaporation Interception Canopy Water Direct Solar Radiation Transpiration Reflected Solar Radiation Emitted Long- wave Radiation Throughfall Stemflow Absorbed Solar Radiation Sublimation Evaporation Infiltration Surface Runoff Snow Melt Soil Heat Flux Soil Water Heat Transfer Redistribution Drainage CAS2K3 Meeting, Annecy September 8-11, 2003

  25. Model Development for new CLM • Biogeochemistry • Goal: Enable parameterization of terrestrial carbon cycle • New hierarchical data structures within a grid cell: grid cell  land unit  snow/soil columns  plant functional types. Does not change climate. • Allow multiple plant types on a single soil column. Minor climate changes. • Biogeophysics I • Goal: Minor changes or bug fixes • Allow precipitation to be rain/snow mix • Improve 2-m temperature diagnostic • Remove discontinuity in bulk density of snow • Biogeophysics II • Goal: Reduce excessive summertime temperatures in arid regions. Reduce Arctic winter warm temperature bias • Turbulent exchange of heat from ground CAS2K3 Meeting, Annecy September 8-11, 2003

  26. Increased Turbulent Heat Flux from Vegetated Surfaces CLM2.2 CLM2 CAS2K3 Meeting, Annecy September 8-11, 2003

  27. Effects on Land Surface Temperatures CLM2.2 CLM2 • 22-year (1979-2000) simulations of CAM2 with CLM2.2 • CLM2.2 significantly cools surface air temperature CAS2K3 Meeting, Annecy September 8-11, 2003

  28. Changes to Physics in CAM3 • Clouds and condensate: • Improved prognostic cloud water & moist processes • Transfer of mixed phase precipitation to land surface • Improved cloud parameterization • Radiation: • Shortwave forcing by diagnostic aerosols • Updated SW scheme for H2O absorption • Updated LW scheme for LW absorption and emission • Surface models: • Introduction of CLM 2.2 • Reintroduction of Slab Ocean Model (SOM) • Energy fixers for dynamics + diagnostics CAS2K3 Meeting, Annecy September 8-11, 2003

  29. Increased Cloud Condensate CAM 3 CAM 2 • Separate cloud liquid and ice variables • Advect cloud condensate • Include latent heat of fusion • Use ice & water variables for cloud optics • New dependence on temperature for cirrus particle size • Sedimentation of cloud droplets and ice particles • Modified evaporation of rain CAM 3 – CAM 2 CAS2K3 Meeting, Annecy September 8-11, 2003

  30. Increased Cloud Amounts CAM 3 CAM 2 • PBL height constrained • Rain rate > 0 • Convection cloud amounts from convective mass fluxes • Stratocumulus clouds in lowest 2 levels • Changes to autoconversion thresholds • Changes to relative humidity thresholds • Fall speed of droplets is function of effective radius CAM 3 – CAM 2 NETTOA = 4.5 Wm2 NETTOA = 0.53 Wm2 CAS2K3 Meeting, Annecy September 8-11, 2003

  31. Global Aerosol Assimilation Climatology 1995-2000 Aerosol Assimilation AVHRR Analysis Aerosol Forcing Analysis NCAR CAM Climate Impacts CAS2K3 Meeting, Annecy September 8-11, 2003

  32. Addition of Prescribed Aerosol Forcing CAS2K3 Meeting, Annecy September 8-11, 2003

  33. Changes in Longwave Cooling Rates:New H2O Lines and Continuum Change in LBL Cooling Change in CAM Cooling CAS2K3 Meeting, Annecy September 8-11, 2003

  34. Global Decrease in Longwave Fluxes CAS2K3 Meeting, Annecy September 8-11, 2003

  35. Changes in Shortwave Heating Rates:New H2O Lines and Continuum Tropics LBL Heating CAM2 Heating CAM2x Heating CAS2K3 Meeting, Annecy September 8-11, 2003

  36. Global Increase in SW Heating Rates CAS2K3 Meeting, Annecy September 8-11, 2003

  37. Global Decrease in Surface Insolation CAS2K3 Meeting, Annecy September 8-11, 2003

  38. Higher Tropopause Temperatures CAM 3 CAM 2 CAM 3 – CAM 2 CAS2K3 Meeting, Annecy September 8-11, 2003

  39. Lower Winter Land Surface Temperatures CAM 3 CAM 2 CAM 3 – CAM 2 CAS2K3 Meeting, Annecy September 8-11, 2003

  40. Cloud Response to Tropical SST Variations CAM 3 CAS2K3 Meeting, Annecy September 8-11, 2003

  41. Cloud Radiative Forcing during ENSOs CAS2K3 Meeting, Annecy September 8-11, 2003

  42. Changes in Precipitation CAM2/CLM2 CAM3/CLM2.2 CAS2K3 Meeting, Annecy September 8-11, 2003

  43. Changes in Coupler & the Sea-Ice Model • Coupler • Improved performance and scaling • Greater flexibility to add new fields • Significant DOE communication infrastructure • Faster multi-way communication to components • Sea Ice • Horizontal advection scheme • Addition of constant salinity in sea ice • Updates to albedos of snow and sea ice • Updates to ridging for thick ice categories CAS2K3 Meeting, Annecy September 8-11, 2003

  44. Global Energy BalanceControl Integration of CCSM3 CAS2K3 Meeting, Annecy September 8-11, 2003

  45. Land Surface TemperaturesControl Integration of CCSM3 CAS2K3 Meeting, Annecy September 8-11, 2003

  46. Ocean Surface TemperaturesControl Integration of CCSM3 CAS2K3 Meeting, Annecy September 8-11, 2003

  47. Surface Wind StressControl Integration of CCSM3 CAS2K3 Meeting, Annecy September 8-11, 2003

  48. Surface InsolationControl Integration of CCSM3 CAS2K3 Meeting, Annecy September 8-11, 2003

  49. Sea-Ice ExtentControl Integration of CCSM3 CAS2K3 Meeting, Annecy September 8-11, 2003

  50. Sea Ice Area and VolumeControl Integration of CCSM3 CAS2K3 Meeting, Annecy September 8-11, 2003

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