Author: Jérôme Chanut, Mercator Océan

Page related to ticket: #1620 and associated to the following development branch: [​https://forge.ipsl.jussieu.fr/nemo/browser/branches/2015/dev_r5847_MERCATOR9_solveur_simplification]

This development is part of the shared simplication process, task: SIMPLIF-2: Removal of filtered free surface. Split explicit and explicit free surface only.

Step 1: Remove filtered free surface option and associated key_dynspg_flt key

1) Remove parts of the code specific to "key_dynspg_flt" or lk_dynspg_flt=T and the need for solver modules in the code.
2) Suppress SOL directory and dynspg_flt module

3) Clean momentum trend routines related to filtered free surface (trddyn, trdken, trd_oce).
4) Update reference configurations:

• Replace key_dynspg_flt by key_dynspg_ts if needed in CONFIG/* directories.
  
• Remove namsol block in namelist_* and references to flt variables (trends) in field_def.xml
  
• SETTE: update sette.sh, to remove modifications of namelist variables related to solver.
  

NB: one should change "solver.stat" file and numsol names in stp_ctl and in_out_manager... keep it as is for the time being

==> Commit changes to revision:5868 https://forge.ipsl.jussieu.fr/nemo/changeset?old_path=%2Fbranches%2F2015%2Fdev_r5847_MERCATOR9_solveur_simplification&old=5867&new_path=%2Fbranches%2F2015%2Fdev_r5847_MERCATOR9_solveur_simplification&new=5868

==> Pass Sette tests:YES

Step 2: Suppress implicit pressure gradient option, ln_hpg_imp=T

Since this option is not supported with the now default split explicit free surface: remove it ( => simpler step routine). ln_hpg_imp namelist variable suppressed in reference namelist.

==> Commit changes to revision: ???
==> Pass Sette tests:???

Step 3: Time Stepping readibility

1) dynzdf
Make time stepping identical in explicit or split-explicit cases => assume that "after" velocities not tendencies are available after vertical diffusion of momentum (as for tracers) => modify dynzdf routines

2) step

• Remove useless conditions depending on ln_dynspg_ts in step. Group all dynamic trends at the same place (at the beginning of the time stepping). Still keep dynnxt after tracer time stepping at the end.
  
• Assuming ua/va are not used anymore during tracer computation as working arrays, remove temporary 3d arrays ua_sv, va_sv

==> Commit changes to revision: ???
==> Pass Sette tests:???

Step 4: additional simplifications

• Remove key_dynspg_ts and key_dynspg_exp cpp keys (create namelist block to choose between the two)
• Suppress dynspg_oce module ?
• Others ?

==> Commit changes to revision: ???
==> Pass Sette tests:???