simplified definition of the model time step

[gm]

the model time step is 2*rdt on dynamics and 2*rdtra on tracers, except at the first time step when starting from rest or when starting from a short restart file (i.e. containing only 1 time step info). In this cas an euler time step is used and thus rdt on dyn and 2*rdtra on tracers. Therefore in many places (tranxt, dynnxt, trazdf, dynzdf, dynspg...) lines similar to the following lines can be found:

      ! set time step length (Euler/Leapfrog)
      IF( neuler == 0 .AND. kt == nit000 ) THEN   ;   r2dt_t(:) =      rdttra(:)      ! at nit000             (Euler)
      ELSEIF( kt <= nit000 + 1 )           THEN   ;   r2dt_t(:) = 2. * rdttra(:)      ! at nit000 or nit000+1 (Leapfrog)
      ENDIF

A significant simplification can be achieved if rdt_d and rdt_t variables are introduced in dom_oce. These variables will be set to the model time step at the beginning of step and used in all routines that need the model time step on dynamics or tracers