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CCSM2 Development & Improvements - Meeting Summary

Learn about the ongoing development of CCSM2, major simulation issues, new components, and planned improvements discussed at the June 2003 meeting. Find out about model biases, ocean modifications, and the goal for state-of-the-art biogeophysics. Explore the scientific and business plans for 2004-2008 and the vision for the future of CCSM. Visit the provided link for more details.

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CCSM2 Development & Improvements - Meeting Summary

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  1. Status of CCSM2.2 Bill Collins Incoming Chair, CCSM Scientific Steering Committee National Center for Atmospheric Research Boulder, Colorado • Development and status of CCSM2.2 • CCSM Science & Business Plans for 2004-2008 • Major simulation issues in CCSM2 • Improvements in components to address biases • WG plans for future improvements & experiments CCSM Meeting June 23-27, 2003

  2. Ongoing Development of CCSM CCSM 2.0 May 2002 Minor changes to code structure CCSM 2.0.1 October 2002 Integration of new components CCSM 2.2 “Late” Spring 2003 Physics adjustments, dycore decision CCSM 2.X Fall 2003 CCSM Meeting June 23-27, 2003

  3. Status of CCSM and its IPCC Applications • CCSM2.2 was completed in June 2003: • New versions of model components • New coupler CPL6 • Test integrations are underway. • Next major issue: decision on atmospheric dynamical core CCSM Meeting June 23-27, 2003

  4. Development Plans for CCSM, 2004-08http://www.ccsm.ucar.edu/management • CCSM Science Plan • Brief history of the CCSM program • Scientific accomplishments of CCSM2 • Status of the CCSM • Planned climate experiments • Near-term program for understanding coupled model • Scientific questions needing major new capabilities • CCSM Business Plan • Current resources • Vision for the future and resource requirements CCSM Meeting June 23-27, 2003

  5. Main Model Biases in CCSM2 • Double ITCZ and extended cold tongue • Cold tongue mitigated in new POP, double ITCZ in CAM 2.X • Overestimation of winter land surface temperatures • Bias largely eliminated in CLM 2.2 + CAM 2.X • Underestimation of tropical tropopause temperatures • Bias reduced in CAM 2.X • Erroneous cloud response to SST changes • Signs and pattern of response corrected in CAM 2.X • Errors in E. Pacific surface energy budget • Overestimation of insolation larger in prototype • Underestimation of tropical variability • Underestimation still present CCSM Meeting June 23-27, 2003

  6. Double ITCZ CCSM Meeting June 23-27, 2003

  7. Winter Land Surface Temperatures CCSM Meeting June 23-27, 2003

  8. Tropical Tropopause Temperatures CCSM Meeting June 23-27, 2003

  9. Cloud Forcing Response to Tropical SSTs CCSM Meeting June 23-27, 2003

  10. East Pacific Surface Energy Budget CCSM Meeting June 23-27, 2003

  11. Tropical Variability CCSM Meeting June 23-27, 2003

  12. Ocean Model Changes for CCSM 2.2 • KPP boundary layer • Double Diffusion • Solar Absorption (Chlorophyll) • Ideal Age and Passive Tracer Infrastructure • Ocean Currents in Air-Sea Fluxes CCSM Meeting June 23-27, 2003

  13. Mixed Layer Depths CONTROL All Physics + Numerical MODS Jan July CCSM Meeting June 23-27, 2003

  14. SST Signature of Solar Absorption CCSM Meeting June 23-27, 2003

  15. SST Signature of All Ocean Modifications CCSM Meeting June 23-27, 2003

  16. New Physics for High Resolution:Anisotropic Mixing CCSM Meeting June 23-27, 2003

  17. New Physics for High Resolution:Reduced Lateral Viscosity CCSM Meeting June 23-27, 2003

  18. 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 CCSM Meeting June 23-27, 2003

  19. Model Development For CLM2.2 • 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 • Fractional cover of snow on ground CCSM Meeting June 23-27, 2003

  20. Increased Reflection of Insolation by Snow CLM2.2 CLM2 CCSM Meeting June 23-27, 2003

  21. Increased Turbulent Heat Flux from Vegetated Surfaces CLM2.2 CLM2 CCSM Meeting June 23-27, 2003

  22. 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 CCSM Meeting June 23-27, 2003

  23. Long-Term Development Tasks TaskScientific Lead Physics Excessive interception Guiling Wang Efficient leaf temperature algorithm Guiling Wang Canopy storage of heat,moisture, CO2 Scott Denning, Ian Baker Sunlit/shaded canopy Peter Thornton Snow hydrology Zong-Liang Yang, Guo-Yue Niu Runoff Zong-Liang Yang, Guo-Yue Niu 2-m temperature over grass Robert Dickinson Surface albedos Xubin Zeng, Robert Dickinson Biogeochemistry Terrestrial carbon cycle Peter Thornton Water isotopes Natalie Mahowald, David Noone Mineral aerosols Natalie Mahowald, Sam Levis Land Cover Change Agroecosystems Gordon Bonan, Johan Feddema, Keith Oleson Urban land cover Gordon Bonan, Johan Feddema, Keith Oleson Prognostic biogeography Sam Levis, Gordon Bonan CCSM Meeting June 23-27, 2003

  24. Changes to Physics in CAM Relative to CAM2 • 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 CCSM Meeting June 23-27, 2003

  25. Increase in Cloud Amount, CWP CAM 2.X – CAM 2 CAM 2.X – CAM 2 CCSM Meeting June 23-27, 2003

  26. Decrease in Clear-sky Surface Insolation CAM 2.X – CAM 2 CCSM Meeting June 23-27, 2003

  27. Cloud Response to Tropical SST Variations CAM 2.X CCSM Meeting June 23-27, 2003

  28. Higher Tropopause Temperatures CAM 2.X CAM 2 CAM 2.X – CAM 2 CCSM Meeting June 23-27, 2003

  29. Lower Winter Land Surface Temperatures CAM 2.X CAM 2 CAM 2.X – CAM 2 CCSM Meeting June 23-27, 2003

  30. Changes in Precipitation CAM2/CLM2 CAM2.x/CLM2.2 CCSM Meeting June 23-27, 2003

  31. 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 CCSM Meeting June 23-27, 2003

  32. Predicting Co-evolution of CO2 and Climate Atmospheric GCM Prognostic CO2 Fossil Fuel CO2 Biophysics + BGC Ocean GCM + BGC • International Geosphere-Biosphere ProgrammeC4 Model Iintercomparsion Project CCSM Meeting June 23-27, 2003

  33. Coupling of NPP and Climate 90W 40N NPP’ [gC/m2/yr] LAI’ [m2/m2] Month (-1) x Tmax’ [K] Year CCSM Meeting June 23-27, 2003

  34. Diurnal Cycle of CO2 CCSM Meeting June 23-27, 2003

  35. Major 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)] CCSM Meeting June 23-27, 2003

  36. 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 CCSM Meeting June 23-27, 2003 mm/year

  37. 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. CCSM Meeting June 23-27, 2003 CCSM2

  38. The Near Future • Tune coupled system over the summer • Perform 100-year control simulations • Select standard atmospheric dycore • Freeze CCSM for IPCC by end of summer • Begin documentation of new model • Begin research on climate sensitivity, etc. CCSM Meeting June 23-27, 2003

  39. Acknowledgements • Jeff Kiehl, for his intellectual leadership and community building • Jay Fein and Dave Bader, for their continued support • The Working Groups, for their efforts in building a new CCSM • Jim Hurrell and Karl Taylor, for their contributions as WG co-chairs • Lydia Shiver and Phil Merilees, for their work on the CCSM Science & Business Plans CCSM Meeting June 23-27, 2003

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