WET_DRY problem for Vstretching=2,3 in set_scoord.F

[rsignell]

If WET_DRY is defined and Vstretching 2 or 3 is used, ROMS will quit with an error message if there it topography above the level of the free-surface (which is generally the case in WET_DRY applications).

There are two problems:

1. Looking at set_scoord.F, I see that the following lines only occur

in the Vstreching == 1 case:

# if defined WET_DRY
       hc(ng)=MIN(MAX(hmin(ng),0.0_r8),Tcline(ng))
# else
       hc(ng)=MIN(hmin(ng),Tcline(ng))
# endif

This code should be executed before the check of which stretching function was used so that it applies to all stretching functions.

2. In the Vstretching=2,3 sections of the code, these lines:

       hc(ng)=Tcline(ng)
       IF (hc(ng).le.hmin(ng)) THEN
        ELSE

and

          WRITE (stdout,10) hc(ng), hmin(ng)
          exit_flag=5
        END IF

should be removed, as in the Vstretching = 1 case.

My modified set_scoord.F is attached.

[rsignell]

set_scoord.F that works with WET_DRY and Vstretching==2 or 3

[arango]

No, really. I actually screw-up! There is not a limitation on hc when using Vtransform=2. This is the advantage of the new transformation, it works for both hc < hmin and hc > hmin This was an issue in the old transformation (Vtransform=1) since we cannot have [h(x,y)-hc] to be negative because dz/ds is also negative!

The check here actually needs to be done in term of Vtransform:

      IF (Vtransform(ng).eq.1) THEN
# if defined WET_DRY
        hc(ng)=MIN(MAX(hmin(ng),0.0_r8),Tcline(ng))
# else
        hc(ng)=MIN(hmin(ng),Tcline(ng))
# endif
      ELSE IF (Vtransform(ng).eq.2) THEN
        hc(ng)=Tcline(ng)
      END IF

and it is independent of the vertical stretching function (Vstretching). Then, the following constraint:

        IF (hc(ng).le.hmin(ng)) THEN

needs to be removed for Vstretching=2,3.

I also corrected a bug associated with hc in ad_set_depth.F, tl_set_depth.F, and rp_set_depth.F. Many thanks to Andy Moore for discovering this bug which was introduced recently.