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Overview of CAM status and simulations

Overview of CAM status and simulations. Bill Collins and Jim Hack National Center for Atmospheric Research Boulder, Colorado. Update on model status, simulations, and release Computational performance of CAM Features of model simulations. Topics. Overview of status and analysis of CAM

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Overview of CAM status and simulations

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  1. Overview of CAM status and simulations Bill Collins and Jim Hack National Center for Atmospheric Research Boulder, Colorado • Update on model status, simulations, and release • Computational performance of CAM • Features of model simulations AMWG Meeting April 3-4, 2002

  2. Topics • Overview of status and analysis of CAM • Discussion of new diagnostic efforts • Discussion of new physics parameterizations • Update on extensions to model • Overviews of work on isentropic coordinates by other modeling groups • Open discussion • Objectives for summer workshop AMWG Meeting April 3-4, 2002

  3. Agenda AMWG Meeting April 3-4, 2002

  4. Developments since June 2001 Workshop Conducted first coupled simulations Implementation/restructuring • implementation of new CAM design: • parameterization interface • creation of constituents module • addition of new ESMF time-manager • continued work on splitting dynamics and physics • incorporated “chunking” data structures (2D decomposition) • other ongoing implementation changes • shared constants, file naming conventions, etc. AMWG Meeting April 3-4, 2002

  5. Developments since June 2001 Workshop Major modifications/improvements: Fractional surface specification implemented and validated • works properly for all three dynamical cores • introduces minor simulation changes CSIM ice thermodynamics implemented and validated • specified and prognostic snow cover implemented and evaluated • slightly colder ice temperatures • reasonable seasonal cycle in snow cover AMWG Meeting April 3-4, 2002

  6. Developments since June 2001 Workshop Numerous “minor” modifications/improvements: • Minghua Zhang prognostic cloud-water closure modification • vertical diffusion on dry static energy • update static energy instead of T between parameterizations • modifications required for coupled simulations • changes to cloud drop number concentration over sea ice • changes to methodology for determining rain vs. snow • other changes required for middle-atmosphere configuration • creation of final boundary datasets • SST and sea ice concentration AMWG Meeting April 3-4, 2002

  7. Upcoming Papers on CAM • General overview • New sea-ice formulation • Finite volume dynamical core • Parameterization for statiform fractional cloudiness • New H2O longwave and cloud overlap • Hydrometeor evaporation mechanism • New global SST climatology • Fractional ice and land • Coupling of parameterizations with dynamical core • Heating and kinetic energy dissipation • Tracer transport AMWG Meeting April 3-4, 2002

  8. Release of CAM to Community • CAM 2.0 and CCSM 2.0 will be released May 17 (’02) • Contents of release: • Model component source code; build and run scripts • Three dynamical cores: Eulerian, semi-Lagrange, and Finite Volume • Web-based documentation • User’s Guide (how to run the model) • Reference Guide (details of the code structure) • Scientific Guide (description of physics and dynamics) • Initial and boundary data sets • New SST and sea-ice concentration data • Model data sets: • AMIP-2 and climatological SST uncoupled integrations(Eulerian dynamics) AMWG Meeting April 3-4, 2002

  9. Computational Performance • Supported platforms: • Compaq • IBM-SP • Linux: Portland group and Lahey compilers • SGI • Sun • Performance: • 1 month per 32 wall-clock minutes on 32 IBM Power3 Pes • Equivalent to ~4 years per wall-clock day on same setup • Reduced grip speed-up: 25-30% (Eul. & SLD uncoupled only) AMWG Meeting April 3-4, 2002

  10. TOA Energy ComponentsFractional Land/Sea Ice vs “Integer” Representation AMWG Meeting April 3-4, 2002

  11. Surface Energy ComponentsFractional Land/Sea Ice vs “Integer” Representation AMWG Meeting April 3-4, 2002

  12. Surface Energy FluxesFractional Land/Sea Ice vs “Integer” Representation Latent Heat Flux Precipitation Rate AMWG Meeting April 3-4, 2002

  13. Surface TemperatureCSIM Thermodynamic Ice vs “Old” Ice Thermodynamics AMWG Meeting April 3-4, 2002

  14. Surface TemperatureCSIM Thermodynamic Ice vs “Old” Ice Thermodynamics AMWG Meeting April 3-4, 2002

  15. New Blended SST-Sea Ice Concentration Data Completed in collaboration with CVWG • blending technique developed by Jim Hurrell • blends HadISST 1949-1980 with Reynolds 1979-2001 • screening technique to ensure reasonable SST-sea ice relationship • PCMDI procedures for ensuring correctness of time interpolation • extensive quality control procedures Fifty-three year dataset (1949-2001) • can easily be extended as new SST data are created by NCEP • currently have completed 21 year control experiment (1979-2000) AMWG Meeting April 3-4, 2002

  16. Southern Oscillation Index AMWG Meeting April 3-4, 2002

  17. Southern Oscillation Index AMWG Meeting April 3-4, 2002

  18. Sea Ice, Snow Height, and Precipitation RateFractional Land/Sea Ice, CSIM Thermodynamics, New SST AMWG Meeting April 3-4, 2002

  19. General Simulation Properties/Framework Scientifically defensible & extendible framework • spectral Eulerian dynamics (reduced-grid capable) • T42 truncation • 26 levels • prognostic cloud water • generalized cloud overlap (plus requisite changes to LW & SW) • updated long wave water vapor absorption formulation • modified deep convection parameterization AMWG Meeting April 3-4, 2002

  20. General Simulation Properties/Framework Improvements in several important simulation features • precipitable water • precipitation distribution • eastern ocean solar energy budget • elements of eastern Pacific surface wind stress Degradations in simulation features • colder troposphere, particularly the tropical tropopause • tendency for more zonal double-ITCZ structure • warm surface temperature bias? AMWG Meeting April 3-4, 2002

  21. Temperature (coupled framework) AMWG Meeting April 3-4, 2002

  22. Surface Temperature (coupled framework) AMWG Meeting April 3-4, 2002

  23. Precipitable Water (coupled framework) AMWG Meeting April 3-4, 2002

  24. Precipitable Water (coupled framework) AMWG Meeting April 3-4, 2002

  25. Precipitation Rate (coupled framework) AMWG Meeting April 3-4, 2002

  26. Surface Stress (coupled framework) AMWG Meeting April 3-4, 2002

  27. Net Longwave Surface Fluxes (coupled) AMWG Meeting April 3-4, 2002

  28. Net Surface Energy Flux (coupled) AMWG Meeting April 3-4, 2002

  29. Surface Temperature (against obs) AMWG Meeting April 3-4, 2002

  30. Eastern Pacific Surface Stress AMWG Meeting April 3-4, 2002

  31. E. Pacific Surface Stress: Resolution Dependence? AMWG Meeting April 3-4, 2002

  32. Future Work Begin ensemble of ~50 year long control simulations • conducted in coordination with Climate Variability Working Group • will serve as the basis for documenting simulation characteristics Accelerate exploration of alternative dynamical frameworks • T31 paleo configuration (update for fractional surface formulation) • T85 configurations (Eulerian and semi-Lagrangian for now) • continued evaluation of simulations with finite-volume dynamical core Begin systematic investigation of specific simulation biases • AMWG should identify short list of prioritized projects • eastern ocean upwelling, double ITCZ, cold tropopause temps, ... • climate sensitivity, variability (e.g., MJO), ... • form teams to develop comprehensive scientific plan of attack • experimental strategy • diagnostic strategy AMWG Meeting April 3-4, 2002

  33. Future Work • AMWG research infrastructure • needs to be able to support research activities on multiple fronts • boundary layer • dynamical cores • stratiform clouds • middle atmosphere (e.g., WACM) • radiation parameterization alternatives • cumulus parameterization alternatives • AMWG diagnostic infrastructure • needs to continue to grow in scope and complexity • evaluate model behavior across wide range of time scales • include dominant modes of climate variability in standard analysis • continued involvement of other CCSM working groups AMWG Meeting April 3-4, 2002

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