CCSM Research Tools: CCSM2.0.1 updates relative to CCSM2.0
Grids and Model Resolutions
New Coarse-Resolution "Paleo" Resolution Supported in CCSM2.0.1
The CCSM2.0 release officially supported only one resolution, referred to as "T42_gx1v3," which was used in the CCSM2.0 Control Run. The CCSM2.0.1 release supports a second, coarser resolution, "T31_gx3v4," which has been validated in a paleo control run. A sample setup for the paleo run can be found in the CCSM2.0.1 release, in the scripts/test.a2 directory. [Return to Contents]
Obsolete Grid Eliminated from CCSM2.0.1
All references to the older, unsupported coarse resolution, T31_gx3, which was never scientifically validated, have been eliminated from CCSM2.0.1
Description of Supported Grid Resolutions
Please refer to the CCSM2.0.1 FAQ page for a discussion on the specifics of the various model grids and resolutions.
Data-Model Input Datasets Updated
The input datasets for the data models were, in many cases, either outdated, incomplete, or both. The following datasets have been updated in the CCSM2.0.1 data models:
- datm -- The forcing datasets have been updated. Two 10-year "F" (active atmosphere, active land, thermodynamic ice, and data ocean model) cases were run for 10 years, one at the "T42_gx1v3" resolution and one at the new "T31_gx3v4" resolution. The last five years of atmosphere-model output are now available for use by the datm model. The datm.setup.csh script has been modified to cycle through only one of these years, but all five are available from NCAR's Mass Storage System (MSS).
- dlnd -- The forcing datasets have been updated. The last five years of the 10-year "F" runs described above are now available for use by the dlnd model. The dlnd.setup.csh script has been modified to cycle through only one of these years, but all five are available from NCAR's Mass Storage System (MSS).
- dice -- The ice-fraction dataset has been updated to use the datasets based upon those created by Jim Hurrell. The ice-fraction data are combined with corresponding sea-surface temperature data into a single file. The data are on a regular, 1-degree latitude/longitude grid. The dice.setup.csh script has been modified to reference this dataset.
- docn -- The sea-surface temperatures from the combined sea-surface temperature/ice-fraction dataset described above is used by the data ocean model. The docn.setup.csh script has been modified to reference this dataset.
Model Bugs Detected and Corrected
Active Atmosphere Model (CAM)
- CAM has an array-allocation problem that does not affect any CCSM2.0 coupled run configurations. It has been fixed in the stand-alone model and in CCSM2.0.1. (reported May 17, 2002)
- CAM has an array-allocation problem in ccsm_msg.F90. It has been fixed in CCSM2.0.1. (reported May 22, 2002)
Active Ocean Model (POP)
- There is a bug in hmix_gm.F in CCSM2.0 POP, which results in not insignificant, but small changes in the results. In tests, the average boundary layer depth changes by 2 - 2.5m in the convection regions in the GIN and Weddell Seas. The average heat flux into the ocean after 30 years is reduced by 0.09 W/m**2. Changes in the barotropic streamfunction are < 1Sv everywhere, and there are very small changes in the meridional overturning and poleward heat flux.
A patch which corrects this error is available on the CCSM2.0.1 download site (patch1). The correction to hmix_gm.F is implemented by default in the test.a2 T31/gx3v4 case, but the patch has not been applied generally because it changes the answers of the control case. Users who are not trying to re-create the control case should apply the patch before running.
- There is a bounds overflow in a physics routine in the CCSM2.0, but only in an option that is not turned on by default. Thus, the overflow did not affect the CCSM2.0 control run. The error occurs when kappa_choice = 'variable' is chosen in the namelist input. The error has been fixed in CCSM2.0.1.
Correction in Reading Restart Files
The CCSM2.0 version will not read b20.007 control run restart files. This has been fixed in CCSM2.0.1.