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Overview of the CCSM

Overview of the CCSM. CCSM Software Engineering Group csm@ucar.edu June 29 2002. What is CCSM?. CCSM is a coupled climate model for simulating the earths climate system. atm. CAM2 AGCM. datm (cycling climate data). Coupler. ice. lnd. CLM. dlnd. CSIM. dice. ocn.

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Overview of the CCSM

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  1. Overview of the CCSM CCSM Software Engineering Group csm@ucar.edu June 29 2002

  2. What is CCSM? CCSM is a coupled climate model for simulating the earths climate system.

  3. atm CAM2 AGCM datm (cycling climate data) Coupler ice lnd CLM dlnd CSIM dice ocn docn (cycling SST data) POP OGCM CCSM Components

  4. CCSM Component Models Atmosphere: NCAR CAM2 • T42 26 levels • 1-D decomposition (64pe limit) • Improved Dynamics, Radiation and Parameterizations Ocean: Parallel Ocean Program (POP1.4.3) • ~1 degree horizontal grid • 40 levels • 2-D data decomposition

  5. CCSM Component Models Sea-Ice: CSIM4 • Elastic-viscous-plastic (EVP) dynamics, ice thickness distribution & energy conserving thermodynamics • High/Low resolutions on POP grids Land: Community Land Model (CLM2) • Global Land surface model • 10 vertical soil layers, 128x64 horizontal points • 16 different vegetated types • Surface hydrology and river runoff

  6. Previous CSM1 and PCM Simulations • greenhouse gas and sulfate aerosol forcing • 1870 control simulation • Historical 1870 to present • IPCC “Business as Usual” assumption • IPCC stabilization assumption • Multi-member ensembles • Solar variability simulation-ensemble of 4

  7. Current CCSM2 Runs • Control (600 years) • 1%/year CO2 increase • Constant 2x CO2 • Control with T85 atm

  8. High Resolution Atmosphere Simulation

  9. Climate Models Expense and work involved with climate predictions and the pretty pictures that result adds an aura of truth to climate model output Don't be fooled…. Climate models are only sophisticated tools, not crystal balls.

  10. Climate Model Given the size of the problem and the finite amount of computer power that can be brought to bear, compromises have to be made. Some important physical processes cannot be represented explicitly. They must be represented approximately by numerical “parameterizations.” Parameterizations are approximations and are not exact. Different parameterizations produce some of the differences in the simulations of different climate models.

  11. Real Climate Model Climate X Adjustment Steady State Solution Time Model Equilibrium Model Climate = Real Climate!!!

  12. Rate of change & variance should be equal Real Climate X Model Climate A E Climate Change Process Time Climate Change Processes

  13. CCSM is considered to be a solid model by the scientific community

  14. Distributed Involvement CCSM is a large community project: NSF / National Center for Atmospheric Research Significant collaborations with: • US university community • US Department of Energy (DOE) • LANL, LLNL, LANL, ORNL, ANL, LBL, NERSC • National Air and Space Administration (NASA)

  15. CCSM Working Groups Scientific development via working groups Atmosphere Model Ocean Model Land Surface Polar Model Climate Variability Paleoclimate Biogeochemistry Climate Change and Assessment Software Engineering Annual CCSM Workshop in Breckenridge Colorado

  16. How can you get involved? • Take part in the CCSM working groups • Feel free to change the code for your own uses, but be sure to validate your science • Don't be afraid to debug problems yourself • Take advantage of your local sysadmins and NCAR consultants to fix problems • If the problem is clearly with the model, check the known bugs area & CCSM Forum, then contact ccsm@ucar.edu

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