AGRIF time step fixer

[mdunphy]

Context

If you set the wrong time step for the child grid, the model corrects it with a message like this:

===>>> : W A R N I N G
         ===============
incompatible time step between grids
parent grid value :           120
child  grid value :           120
value on child grid will be changed to :           40

However, this correction occurs too late in the initialization, and the wrong value is propagated to other variables before it is corrected.

Analysis

The routine dom_stp sets rdttra(:) = rdt after we read namelist namdom, but before the time step controlling above, so the model proceeds with the uncontrolled time step for tracers (despite using the correct controlled time step for dynamics)

Fix

Option 1) the controlling of the child grid time step should move from agrif_user.F90/Agrif_InitValues_cont to domain.F90/dom_nam where we read namelist namdom

Option 2) change agrif_user.F90/Agrif_InitValues_cont to stop upon mismatch because it is too late to 'fix' the value at this stage of the initialization

[mdunphy]

Patch for Fix #1, moving the control from agrif_user.F90 to domain.F90

[jchanut]

Thanks for reporting this.
Option 2), ie a "STOP" has in fact already been retained in the trunk. Probably better to put AGRIF stuff as much as possible in AGRIF modules.
Changes done at revision 8636