Report on CCSM Atmosphere Model Working Group Meeting
Broker Inn, Boulder, Colorado
Co-Chairs: Bill Collins and Dave Randall
April 3 and 4, 2002

The schedule of talks and the introductory presentation regarding the status of CAM are available on the CCSM AMWG website.

The meeting covered:

The discussion centered on redirecting some of the effort within the AMWG toward biases in coupled simulations. The group agreed that the AMWG should attempt to agree, as a group, on a few key biases, on methods for analyzing these biases, and on strategies for beginning to address these problems.

The main systematic errors discussed were:

1.  The double ITCZ

2.  Underestimation of tropical variability on short (<1 week) timescales and poor representation of the Madden-Julian Oscillation (MJO)

3.  Overestimation of land surface temperatures in winter

4.  Underestimation of the tropical tropopause temperatures

5.  Biases in the eartern Pacific related to boundary layer clouds and surface wind stress


The group discussed the steps necessary to begin analysis of these problems:

1.  Formulation of hypotheses for why the errors occur

2.  Experimentation of alternative physics formulations in both coupled and uncoupled frameworks

3.  "Partial derivative" experiments using observations, for example, testing the sensitivity of the model to prescribed winds from the European Remote Sensing satellite (ERS) and clouds from the International Satellite Cloud Climatology Project (ISCCP)

4.  Column diagnostics based upon Atmospheric Radiation Measurements (ARM) data, buoys from eastern Pacific, etc.

It was agreed that this experimental strategy and the key systematic errors would be discussed in detail at the June 2002 AMWG meeting.

The group also discussed the need to explore higher resolutions and dynamical cores. The AMWG will discuss the possibility of doing all future experimentation using the Finite volume (FV) dynamical core for several reasons:

1.  It could provide another mechanism for diagnosing the model using the results from the Data Assimilation Office (DAO) assimilation effort

2.  It is much better suited for chemistry applications

3.  It is the core adopted by the Whole Atmosphere Community Climate Model (WACCM)

4. It can be adapted to use isentropic coordinates

5. It provides superior computational performance on massively parallel systems to the standard Eulerian core

As an action item, the AMWG will work with the CCSM scientists and software engineers to begin a coupled integration using the FV CAM in the near future.

PARTICIPANT LIST:
1. Bill Collins, NCAR
2. Dave Randall, CSU
3. Byron Boville, NCAR
4. Steve Ghan, PNL
5. Phil Merilees, NRL
6. Cecilia Bitz, U Washington
7. Jim Hack, NCAR
8. Jim Hurrell, NCAR
9. Jeff Kiehl, NCAR
10. Caspar Ammann, NCAR
11. Warren Washington, NCAR
12. Bette Otto-Bliesner, NCAR
13. Phil Rasch, NCAR
14. Dave Williamson, NCAR
15. Fabrizio Sassi, NCAR
16. Aime' Fournier, NCAR
17. Tom Bettge, NCAR
18. Jeff Anderson, NCAR
19. Jerry Olson, NCAR
20. David DeWitt, IRI
21. John Bergman, CDC/NOAA
22. Minghua Zhang, SUNY
23. Brian Eaton, NCAR
24. Eric Maloney, NCAR
25. Bill Putnam, SAIC/GSFC/DAO
26. Vasu Misra, COLA
27. Bruce Briegleb, NCAR
28. Mark Stevens, NCAR
29. Chin-Hoh Moeng, NCAR
30. Jiundar Chern, GSFC DAO
31. Tom Ackerman, PNL
32. Celal Konor, UCLA
33. Hongbin Yu, GaTech
34. Graeme Stephens, CSU
35. Norm Wood, CSU
36. Jerry Potter, LLNL
37. Karl Taylor, PCMDI
38. Jim Boyle, PCMDI
39. DeZheng Sun, NOAA
40. John Fasullo, PASO
41. Tao Zhang, ERL
42. Wuiyin Lin, SUNY
43. Marat Khairoutdinov, CSU