update 3D momentum trends to work with split-explicit timestepping (NEMO 4.2)
Development description
Update code to output 3D momentum trends to work with split explicit timestepping at NEMO 4.2.
This is part of item 42 on the 2024 work plan. The issue is a long-standing one documented here: https://forge.ipsl.jussieu.fr/nemo/ticket/2344
This issue documents the update of the 4.2 code. A separate issue will be created to deal with the update of the 5.0 code.
Code implementation
Describe flow chart of the changes in the code.
List the Fortran modules and subroutines to be created/edited/deleted.
Detailed list of new variables to be defined (including namelists), give for each the chosen name and description wrt coding rules.
Documentation updates
Using previous parts, define the main changes to be done in the doc (manuals, guide, web pages, ...).