1. The Community Climate System Model (CCSM): An Overview Jim Hurrell Director Climate and Global Dynamics Division jhurrell@ucar.edu Climate and Ecosystem Community Planning Meeting November 2-3, 2005 Boulder, CO

2. A comprehensive climate model to study the Earth’s Climate. Widely used to investigate the mechanisms of seasonal, interannual and longer-term variability. Explore the history of Earth’s climate. Estimate the future of the environment for policy formulation. http://www.ccsm.ucar.edu The Community Climate System Model

3. Evolution of CCSM J. Climate, 1998 (Boville and Gent, 1998) CSM 1.0 June 1996 Kiehl and Gent, 2004 CCSM 2.0 May 2002 New ocean, land, sea-ice models New physics in atmospheric model J. Climate, 2006 (Collins et al., 2006) IJHPCA, 2005 CCSM 3.0 June 2004 New physics in all components

4. Configuration of NCAR CCSM3 Atmosphere (CAM 3.0) T85 (1.4 o ) Ocean (POP 1.4.3) (  1 o ) Coupler (CPL 6) Sea Ice (CSIM 4) (  1 o ) Land (CLM 3.0) T85 (1.4 o )

5. Standard Configurations T31 x 3T42 x 1 T85 x 1 To facilitate its application, CCSM has been ported to both vector and scalar supercomputers as well as Linux clusters On an IBM SP4 system, the low, intermediate and high resolution configurations require 62, 292, and 1146 CPU hours to simulate one year (Yeager et al. 2006)

6. Atmosphere Model Working Group Ocean Model Working Group Land Model Working Group Polar Climate Working Group Paleoclimate Working Group Climate Variability Working Group Biogeochemistry Working Group Climate Change Working Group Software Engineering Working Group CCSM SSC CCSM Advisory Board Chemistry- Climate Working Group Organization of the CCSM Project

7. Contributions to IPCC Fourth Assessment Three phases: –Pre-industrial (1870) –20th Century (1870-2000) –Emissions Scenarios SRES Scenarios: –Commitment (20 th C. CO 2 ) 2000-2100 (8 runs) 2100-2200 (4 runs) –A1B and B1 Scenarios 2000-2100 (8 runs) 2100-2200 Const (5 runs) 2200-2300 Const (1 run) –A2 Scenario 2000-2100 (8 runs) A1B B1 Commitment

8. Contributions to IPCC Fourth Assessment Output: 10 GB/simulated year Data volume for IPCC: ~100 TB Largest contribution of any model Eight ensemble members at T85 for each experiment Data available online: PCMDI (IPCC archive) ESG (Control) Original history tapes: SCD Diagnostics on line (web)

9. Objectives  Describe CCSM3 to the climate community  Document CCSM3 for IPCC FAR Topics  Overview of CCSM3  Description of climate state for each component model  Responses (paleoclimate; pre-industrial; 20 th & 21 st Century)  Major modes of coupled variability  Climate sensitivity CCSM J. Climate Special Issue (http://www.ccsm.ucar.edu/publications/jclim04)

10. Recent Science Highlights CCSM J. Climate Special Issue 26 papers  SSC (1)  Atmosphere Model (6)  Ocean Model (4)  Land Model (2)  Climate Change (2)  Climate Variability (4)  Polar Climate(4)  Paleoclimate (3) 680 pages (estimated) Authorship  51 NCAR (22 lead authors)  48 External

11. 99% sig. Improved SLP Teleconnections to ENSO CCSM Simulation Improvements

12. Recent Science Highlights CCSM IJHPCA Special Issue Objectives  Describe SE for climate models  Document performance and portability 14 papers submitted Authorship  14 NCAR (3 lead authors)  27 External