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An Introduction to NCAR Community Climate System Model (CCSM)

An Introduction to NCAR Community Climate System Model (CCSM). Wanli Wu (wanliwu@ucar.edu) National Center for Atmospheric Research (NCAR). What is CCSM. Community Climate System Model, one of elite climate models in the world to picture the complexity of the Earth’s climate.

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An Introduction to NCAR Community Climate System Model (CCSM)

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  1. An Introduction to NCAR Community Climate System Model (CCSM) Wanli Wu (wanliwu@ucar.edu) National Center for Atmospheric Research (NCAR)

  2. What is CCSM • Community Climate System Model, one of elite climate models in the world to picture the complexity of the Earth’s climate. • It has been developed by NCAR scientists in collaboration with researchers at Universities, National Laboratories. • The CCSM program is sponsored by US NSF and Dept. of Energy. • It houses at National Center for Atmospheric Research with open source codes, documents for all interested users in the world.

  3. Develop a comprehensive model to study the Earth’s Climate. Investigate seasonal and interannual variability of the climate. Explore the history of the Earth’s climate. Estimate the future of the climate. Release of a new version (CCSM3, June, 2004). Studies linking SST fluctuations, extreme events and extratropic variability. Simulations of paleoclimate. Contributions to IPCC AR4. Special issues: J. Climate (June 1, 2006) and IJHPCA (2005) CCSM Program:Scientific Objectives & Recent Accomplishments

  4. The GCM Family Tree

  5. Evolution of Community Climate System Model (CCSM)

  6. Complexity of Models: Broader and Deeper

  7. Models of Everything

  8. Modules of Models

  9. CCSM: components • atm: Atmospheric model (CAM3, T85L26) • lnd: Land model (CLM3, T85) • ocn: Oceanic Model (POP 1.4, x1L40) • ice: Sea ice model (CSIM5, x1) • cpl: Coupler (CPL 6)

  10. CCSM3: Computational Requirements • IBM power 3-5 • SGI Altix & Origin • Cray X1/X1E & XT3 • NEC SX • Xeon & Itanium Linux On IBM power 4: T85x1 1146 CPU hrs/myr T42x1 293 CPU hrs/myr T31x3 62 CPU hrs/myr

  11. The Atmospheric model: CAM • Dynamics: • Spectral • Finite volume • Physics: • Deep & shallow convection • Prognostics condensate & precipitation parameterization • Diagnostic parameterization of cloud fraction • Band-model radiative transfer • Prognostic and diagnostic aerosols

  12. Horizontal grids of the Atmospheric Model

  13. The Land model: CLM

  14. CLM sub-grid Hierarchy

  15. The Ocean model: POP • A Bryan-Cox type and z-coordinate model. • Controlled by primitive equations subject to hydrostatic & Boussinesq approximations. • Conserved global ocean volume • Gent-McWilliam isopycnal mixing • KPP vertical mixing • x1L40 or x3L25 • 1/10 degree

  16. POP Grids

  17. Sea ice model: CSIM • Ice dynamics • Ice thermodynamics • Subgrid scale ice thickness distribution (ITD)

  18. Coupling methodology • The physical component models communicate through the coupler in a completely asynchronous manner (different grid and different time steps). • The coupler • governs the execution and time evolution of the entire system. • provides interface flux conditions and state information to each model. • enforces flux conservation.

  19. Model climatology: zonal mean air temperature

  20. Model climatology: improved from CCSM2

  21. Model climatology: sea surface temperature

  22. Model climatology: improved SST

  23. Model climatology: Continental temperature biases

  24. Model climatology: precipitation

  25. Model climatology: improved precipitation

  26. Model climatology: seasonal cycle of sea ice

  27. CFC-11 Inventory

  28. Regional features: N. Atlantic CFC-11

  29. Regional features:Tibet Plateau surface climate

  30. Regional features: south Asia monsoon

  31. Tropical variability: ENSO variance

  32. Tropical variability: ENSO power spectra

  33. Tropical variability: Symmetric equatorial waves

  34. Tropical variability:Asymmetric equatorial waves

  35. Pressing Issues, Challenges & Opportunity • Representation of major variability modes • Pacific double ITCZ • Continental precipitation and temperature biases • Eastern Ocean boundary SST biases • Eastern Pacific semiannual SST cycle • Arctic downward short-wave radiation bias

  36. Work in progress: Chemistry • Atmospheric chemistry • Terrestrial C/N cycle, ecosystems • Marine biogeochemical cycle

  37. Work in progress: Nesting • WRF --> CAM • ROMS --> POP

  38. Work in progress: weather-climate interaction • Crossing-scale interaction • Test climate models as weather models

  39. Work in progress: tropical variability • Reduce tropical biases related to MJO, ENSO

  40. Work in progress: Air quality/pollution vs. climate • Climate model application

  41. CCSM4: Community Earth System Model (CESM, 2009?) • A model of everything • More component model options

  42. Community Earth System Model

  43. THANK YOU

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