1. CCSM3’s IPCC Simulations and Lessons Learned
Bill Collins
National Center for Atmospheric Research
Boulder, Colorado
IPCC Production and Data Transfer
Scientific results from IPCC Simulations
Lessons Learned

2. Contributions from CCSM to IPCC
IPCC Emissions Scenarios
CCSM3 Simulations
IPCC 4th Assessment
This slide shows three examples of how CCSM will contribute to IPCC, and so I can point out that new understanding from MMAP could pontentially have an impact on our contributions to international assessments and policy formation that would be far-reaching.
Results:
10,000 simulated years
Largest submission to IPCC
100 TB of model output

3. The Experimental Configuration (from IPCC TAR)
A1B B1

4. Production Schedule of IPCC Runs

5. IPCC Ensembles on US Machines

6. US Simulations for IPCC FAR
Phase
Run
Ensemble Members
Base
Extensions
Total
Years 1
1870
440
Coverage of
870 2
20th C. 5
130
650 3
Constant
500
A1B
2300 (1 )
1100 A2 B1
Controls
1990
1%CO2
450
5670

7. Computational Resources for Simulations
Execution speed: 3.5 years/day on 192 IBM Power-4 CPUs
Time required to simulate 5370 years: 5670 / 3.5 = 1620 wall-clock days
CPU time for 1 simulated year: 1146 CPU hours
Equivalent number of CPU hours for IPCC runs: 5670  1146= 6.5  106 CPU hours

8. IPCC Ensembles on the Earth Simulator
All data has been transferred to NCAR mass store.

9. Statistics of the IPCC Ensembles
Ensemble size:
20th Century: 8
A1B Scenario: 8
B1 Scenario: 8
Commitment: 8
A2 Scenario: 5
Total integration: 10,800 years
Data volume: ~110 TB

10. Resolutions for all Modeling Groups
Karl Taylor, PCMDI

11. Model Simulations by all Groups
Karl Taylor, PCMDI

12. Transfer of the Data to PCMDI
First 1-TB disk transferred to PCMDI in October. Three Disks are now in use.
CCSM IPCC data is now on the PCMDI IPCC website:
Estimated scheduling of data transfers:
Details:
Sequence:
20thC:
CAM monthly
CAM daily/6hr
CLM monthly
Controls:
Scenarios
POP and CSIM monthly to follow.

13. Papers on CCSM IPCC Scenario Runs
Meehl et al, 2005: How much more global warming and sea level rise? In press, Science
Meehl et al, 2005: Climate change in the 20th and 21st centuries and climate change commitment in the CCSM3 Submitted to J. Climate
Bryan et al, 2005: Response of the North Atlantic Thermohaline Circulation and Ventilation to Increasing Carbon Dioxide in CCSM3 Submitted to J. Climate
Kyosei Consortium, 2005: Analysis of CO2 overshoot experiments

14. Global Temperature and Sea Level

15. Ocean Temperature and Overturning

16. Increases in Surface Temperature

17. Increases in Precipitation

18. Arctic Sea Ice Concentrations

19. Changes in Sea Ice Coverage

20. Lesson #1: Experimental Design Plan
Contents & goals of the experiments
Description of all forcing agents vs. time
Description of pre-industrial spin-up
Pre-industrial configuration tuned for energy balance?
Simulation for year 2000 integrated backwards to 19th C.?
Experimental basis for pre-industrial spin-up
Description and plan for CCSM resource requirements
CCSM software engineering support
Development efforts by working groups and WG liaisons
Plan and timeline for dissemination of experiments
Distribution within the CCSM community
Distribution to wider climate community

21. Lesson #2: Development of Forcings
20th Century
21st-23rd Century
Greenhouse Gases
Observed
SRES
Ozone
Trop: MOZART
Strat: Solomon
Trop:MOZART scaled by O3 TAR forcing
Sulfate Aerosols
SO2: Smith/Wigley
SO2: SRES
Carbon Aerosols
Population Scaling
SO2 Scaling
Sea-salt & Dust
Year 2000 values
Volcanic Aerosols
Ammann (2003)
Solar Variation
Lean (1995)
Indirect Effects
None

22. Aerosol Optical Depths during 20th C.
Sulfates
Black & Organic
Carbon
Strat. Volcanics

23. Present-day Aerosol Optical Depths

24. Comparison of CCSM3 and Global Surface Temperatures
Please see the attached PowerPoint file containing plots of
globally averaged TS using the all-forcing runs of the CCSM3.
Only 4 of the b ensemble members were available when I made
these. I can update them with the 5th member and the ES members
if you would prefer. The shading shows the ensemble spread and
the solid lines the ensemble average. The black line is the
observations used in the IPCC TAR (Folland et al 2001).
Bias at end of run = ??
Eight-member ensemble:
T85 atmosphere & land
1-degree ocean & sea-ice
Meehl et al, 2004

25. Recommendations on Forcings
Coordination with other groups:
For example, Boucher’s shared SO4 data set
Efforts for AR4 to develop common forcings
Develop components of state-of-art forcings:
Emissions as functions of space and time
Chemical transport framework to simulate agents
Parameterization development for indirect effects
Exploration of indirect forcings, for example
Effects of irrigation
Effects of land-use change

26. Lesson #3: Design of Model Spin-up

27. Effects of Energy Balance on Ocean Temperature in 1870 Control
Trend = 0.17 K/Century

28. Lesson #4: (Ideally) Start Early
Sequential, not concurrent, mile-stones:
Release of CCSM3 to the community
Peer-reviewed documentation of CCSM3
Execution of IPCC experiments
We did all of these in 2004!

29. Lesson #5: Check Throughput of Data Transfer

30. Lesson #6: Plan for all End Users
Issue: CCSM output = 100 TB
This is orders of magnitude more data than our colleagues in IPCC WG2 and WG3 are used to analyzing.
How do we make the data accessible & usable?
Recommendations for steps forward:
NCAR’s GIS tool for model output?