1. The Next Release of CCSM: IPCC and Community Applications
Bill Collins National Center for Atmospheric Research
Boulder, Colorado

2. Development History of CCSM
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

3. Configuration of CCSM for IPCC
Atmosphere
(CAM 3.0)
T85 (1.4o)
Land
(CLM2.2)
T85 (1.4o)
Sea Ice
(CSIM 4)
(1o)
Coupler
(CPL 6)
Ocean
(POP 1.4.3)
(1o)

4. 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

5. Atmospheric Dynamics and Resolution
Goal for IPCC: T85 (1.4o) or equivalent FV resolution
Improved resolution for regional impact studies
Improved resolution for fidelity in coastal stratus regions
Recommendation on atmospheric dynamics:
Eulerian for standard IPCC scenario applications
Finite Volume for future development and experimentation
Goal for CCSM: Single physics package for multiple dynamics & resolutions:
T85
11
T42
22.5
T31 ….
IPCC
AMWG, CVWG, Paleo, …
Resolution
BGCWG
Dynamics

6. Main Model Biases in CCSM2
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
Stress, latent heat flux, and insolation better in T85 CAM
Double ITCZ and extended cold tongue
Cold tongue mitigated in new POP
Underestimation of tropical variability
Underestimation still present

7. Winter Land Surface Temperatures

8. Tropical Tropopause Temperatures

9. Cloud Forcing Response to Tropical SSTs

10. East Pacific Surface Energy Budget

11. Double ITCZ

12. Tropical Variability

13. Ocean Model Changes for CCSM 3.0
KPP boundary layer
Solar Absorption (Chlorophyll)
Double Diffusion
Ideal Age and Passive Tracer Infrastructure
Ocean Currents in Air-Sea Fluxes

14. Mixed Layer Depths
CONTROL
All Physics + Numerical MODS
Jan
July

15. SST Signature of Solar Absorption

16. SST Signature of All Ocean Modifications

17. 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
Latent Heat Flux
Sensible Heat Flux
Photosynthesis ua
Momentum Flux
Wind Speed
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
Melt
Snow
Soil Heat Flux
Soil Water
Heat Transfer
Redistribution
Drainage

18. 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

19. Turbulent Heat Flux from Vegetated Surfaces
CLM2.2
CLM2

20. Effects on Land Surface Temperatures
CLM2.2
CLM2
22-year ( ) simulations of CAM2 with CLM2.2
CLM2.2 significantly cools surface air temperature

21. 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

22. 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

23. 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

24. Global Aerosol Assimilation Climatology
Aerosol Assimilation
AVHRR
Analysis
Aerosol Forcing
Analysis
NCAR CAM
Climate Impacts

25. Addition of Prescribed Aerosol Forcing

26. Changes in Longwave Cooling Rates: New H2O Lines and Continuum
Change in
LBL Cooling
Change in
CAM Cooling

27. Global Decrease in Longwave Fluxes

28. Changes in Shortwave Heating Rates: New H2O Lines and Continuum
Tropics
LBL Heating
CAM2 Heating
CAM2x Heating

29. Global Increase in SW Heating Rates

30. Global Decrease in Surface Insolation

31. Higher Tropopause Temperatures
CAM 3
CAM 2
CAM 3 – CAM 2

32. Lower Winter Land Surface Temperatures
CAM 3
CAM 2
CAM 3 – CAM 2

33. Cloud Response to Tropical SST Variations

34. Changes in Coupler & the Sea-Ice Model
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

35. Surface Temperatures: CCSM T85 Control

36. Sea-Ice Area: CCSM T85 Control

37. Sea-Ice Thickness: CCSM T85 Control

38. Land Surface Temperatures: T85 Control

39. Tropical Surface Stress: T85 Control

40. Surface Insolation: CCSM T85 Control

41. ENSO Variability: CCSM T85 Control

42. Nino Index Variability: CCSM T85 Control

43. Changing Resolution: Surface Stress

44. Changing Resolution: Surface Insolation

45. Changing Resolution: Total Precipitation

46. Changing Resolution: Sea-Surface Temperature

47. Changing Resolution: Pacific Temperature

48. Changing Resolution: Surface Salinity

49. Changing Resolution: Pacific Salinity

50. Changing Resolution: Pacific Currents

51. Decision Schedule for IPCC
Recommendation for IPCC configuration: CCSM Scientists’ Meeting, Nov. 12
Data for decision:
T85 integrations for 3 options of 50+ years
T85 SOM integrations for 1x, 2xCO2
T85 AMIP/warm-cold integrations (ENSO)
Analogous data for T42
Final evaluation and decision for IPCC: SSC Meeting, Nov

52. Release of CCSM3 to the Community
Contents of release:
Model physics: all components = IPCC
Model data sets: controls for T31,T42, & T85
Technical documentation
Schedule for release: Winter 2004
Documentation in literature: J. Climate special issue?
Release of IPCC model data sets?

53. Climate Sensitivity: T42 CAM + SOM

54. IPCC Schedule

55. Scenarios: IPCC Fourth Assessment Report

56. NCAR’s IPCC Production Schedule
CCSM Execution Speed on NCAR IBM:
T42 ATM: 10.9 years/day
T85 ATM: years/day

57. Development Plans for CCSM, 2004-08

58. CCSM: The Next Two Years
Roadmap to the future
Climate sensitivity from IPCC studies
Process studies from GFDL collaboration, CPTs
Studies of higher resolution and “benchmark” calculations
News physics/dynamics from Science Plan
Integration of climate and chemistry
Ocean and land biogeochemistry
Prognostic aerosols
Tropospheric chemistry
WACCM
Tracers

59. The Evolution of CCSM

60. Computational Demands for CCSM Science

61. Conclusions A new version of CCSM is ready for IPCC Features of CCSM3:
Improvements in component physics
Ability to run with multiple resolutions, dycores
Issues for the near future:
Final decisions regarding model configuration
Definition of public release
Completion and analysis of IPCC integrations
Integration of coupled carbon-climate experiments
Issues for the longer term:
Addition of new scientists in emerging focal areas
Access to significant new computational resources

62. Sea-Ice Concentration: CCSM T85 Control

63. Changing Resolution: Arctic Salinity

64. Changing Resolution: Temperature Cycle