CESM Models

CCSM4.0 CICE Validation

 

In a successful port, CCSM CICE sea ice model solutions are expected to be the same "to roundoff level" as solutions generated on a trusted machine, although determining what is and what is not roundoff level is somewhat difficult and subjective. Presently no automated testing tools exist for validating the successful port of the CCSM CICE model to a new system.

In order to facilitate the evaluation of a successful port, we suggest that you set up and run on your local machine the two cases described below. When time permits, we plan to create scripts to automatically set up and run those cases, but until then, you will need to apply these steps manually.

Following the successful execution of these two cases, you can run a script to determine the error growth in sea ice thickness over a five-day run. Next, you can run the ice diagnostics package on a ten-year run to verify that the simulations are indistinguishable or not. A succesful port should have an RMS error difference of less than 0.001 m difference in global ice volume in the five day test and the ten-year runs should be nearly indistinguishable in the time series plots. Spatial differences in the two runs will be larger, but these should appear to be random with a fairly equal distribution of plus and minus differences. While more systematic differences may not indicate a problem, these are usually indicative of a problem with the port, particularly with larger RMS differences.

Port-Validation Plots

The following plots illustrate a successful port to the NCCS Cray XT jaguar. The plots display timeseries of RMS differences of the sea ice volume field between the jaguar solutions and those generated on a "trusted machine," the NCAR IBM bluefire.

The following plots illustrate a successful port to the Argonne National Laboratory IBM Blue Gene/P intrepid. The plots display timeseries of RMS differences of the sea ice volume field between the intrepid solutions and those generated on a "trusted machine," the NCAR IBM bluefire.

The CICE diagnostic plot page is available at:

Tools

The CICE diagnostic package is available at:

The sea ice thickness difference script is available at:

Contact the PCWG liaison to obtain the datasets or help with this procedure.

 

Model Source Code

Copyright and Terms of Use

All CCSM source code is subject to the following Copyright Notice and Disclaimer.

Acquiring the Code

CCSM source code is distributed through a public Subversion code repository. This code can be checked out using Subversion client software, such as the command tool svn, or simply viewed with a web browser.

A short registration is required to access the repository. After registering, you will receive an email containing a user name and password that is necessary to gain access to the repository.

Acquistion of the code is more fully described in the CCSM4.0 User's Guide.

Version Summaries and Known Problems

The following table lists the available versions of code along with their test record and any known problems in the code.

Reporting a Problem

If you have any problems, please first read the User's Guide including the sections on FAQs and Use Cases. Please also refer to the CCSM Bulletin Board, which is in place to facilitate communication within the CCSM community. Finally, please also refer to the Known Problems entries that are provided with every release and release update. If questions or problems still exist, then please send an email to ccsm4-help@cgd.ucar.edu. Support questions will be answered as resources are available.