[[PageOutline]] Last edited [[Timestamp]]

'''Author''' : Tim Graham

'''ticket''' : [ticket:1306 #1306]

'''Branch''' : https://forge.ipsl.jussieu.fr/nemo/browser/branches/2014/dev_r4650_UKMO12_CFL_diagnostic

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=== Description ===
Add a module to calculate and output the maximum CFL number during a model run. This can be used to inform users if they are close to exceeding CFL stability criterion.

The code exists in a local branch at NEMO3.4 and minimal changes should be required to implement this in the latest NEMO version.

The changes will consist of adding one new module and a single call to it in step.F90. The output is written to an ascii file.

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=== Testing ===
The code will be SETTE tested.
A short (few time step simulation) will be run with timestep level output. The CFL calculations can then be checked offline using python code.

|| NVTK Tested || !'''YES/NO!''' ||
|| Other model configurations || !'''YES/NO!''' ||
|| Processor configurations tested || [ Enter processor configs tested here ] ||
|| If adding new functionality please confirm that the [[BR]]New code doesn't change results when it is switched off [[BR]]and !''works!'' when switched on || !'''YES/NO/NA!''' ||

(Answering UNSURE is likely to generate further questions from reviewers.)

'Please add further summary details here'

 * Processor configurations tested
 * etc----

=== Bit Comparability ===
|| Does this change preserve answers in your tested standard configurations (to the last bit) ? || !'''YES/NO !''' ||
|| Does this change bit compare across various processor configurations. (1xM, Nx1 and MxN are recommended) || !'''YES/NO!''' ||
|| Is this change expected to preserve answers in all possible model configurations? || !'''YES''' ||
|| Is this change expected to preserve all diagnostics? [[BR]]!,,!''Preserving answers in model runs does not necessarily imply preserved diagnostics. !'' || !'''YES''' ||

If you answered !'''NO!''' to any of the above, please provide further details:

 * Which routine(s) are causing the difference?
 * Why the changes are not protected by a logical switch or new section-version
 * What is needed to achieve regression with the previous model release (e.g. a regression branch, hand-edits etc). If this is not possible, explain why not.
 * What do you expect to see occur in the test harness jobs?
 * Which diagnostics have you altered and why have they changed?Please add details here........

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=== System Changes ===
|| Does your change alter namelists? || !'''YES/NO !''' ||
|| Does your change require a change in compiler options? || !'''YES/NO !''' ||

If any of these apply, please document the changes required here.......

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=== Resources ===
!''Please !''summarize!'' any changes in runtime or memory use caused by this change......!''

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=== IPR issues ===
|| Has the code been wholly (100%) produced by NEMO developers staff working exclusively on NEMO? || !'''YES/ NO !''' ||

If No:

 * Identify the collaboration agreement details
 * Ensure the code routine header is in accordance with the agreement, (Copyright/Redistribution etc).Add further details here if required..........