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Testing POP

The POP distribution includes a simple test case that can be used for a variety of purposes, including validation, performance tuning and benchmarking. The key point is that there are no input fields: the model grid, topography, initial state, equation of state coefficients and wind stress (there is no other forcing enabled) are all generated internally. The only file that is read is pop_in.

To run the test problem, type

./setup_run_dir test test

and a directory called test will be created that contains all of the appropriate files. The default model size is 192x128x20 grid points, though this can be changed arbitrarily by the user. The grid generated internally is an equally-spaced latitude-longitude global grid with idealized landmasses. Make the executable as described earlier. The pop_in file defaults to running 20 steps with full diagnostics output every step. Note that for performance benchmarks, the diagnostic frequency should be set to 'never' as the global diagnostics are expensive and typically requested relatively infrequently (e.g. every 10 days) in a production simulation.

To use this test case for validation, the user can compare their ouput with the file pop/input_templates/pop_sgi.log.test which contains the output of a 20 step calculation run on 4 processors of an SGI Origin3000. The results from other computer platforms should agree reasonably well - within roundoff for the first step for most of the larger fields (the nearly-zero fields are very sensitive and my not agree to that level of precision).

Once the answers have been validated using the 192x128x20 grid, performance and scaling can be investigated by varying the grid size (in domain_size.F90) and the number of processors (in the pop_in file).

CESM1 Notes

CESM1 scripts support a wide variety of testing support which are described in the Porting CESM1 and CESM1 Tests sections of the CESM1 User's Guide.

See for CESM1 POP2 port-validation instructions.

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