Add a new MLD diagnostic to NEMO. The diagnostic will be based on a 0.2K change in temperature from the surface - this is the same definition as used by deBoyer ​http://www.ifremer.fr/cerweb/deboyer/mld/home.php.

This will add an additional mixed layer depth diagnostic NEMO outputs, with the output controlled by a namelist. This criterion is used by the Met Office's data assimilation system in shelf seas.

This is a simple update to add a new diagnostic and it will not change any physics. Consequently the only tests I propose are:

1. Run the stem tests.
2. Verify the diagnostic by running the model for a few days and verifying that the MLD is output. The values obtained can then be compared to the deBoyer MLD climatology to make sure they are sensible.

Paolo are you happy with these tests?

This configuration is OK on "mercure" NEC-SX8R platform at CCRT with

• NEMO trunk revision 1340
• libIGCM trunk revision 85

and without monitoring and atlas

1 year run - trunk of 12 months in one job with diagnostics