[MITgcm-support] spatially variable bottom drag

[Martin Losch]

Hi Mike,

With your “SIZE.h” (nSx=nSy=1), the bi/bj can only be one, so that shouldn’t worry you. There’s a PR https://github.com/MITgcm/MITgcm/pull/574 <https://github.com/MITgcm/MITgcm/pull/574> where I added 2D quadratic drag coefficient fields, maybe you can use that as a template, but I think you are already on the right track.

Martin

> On 12. Apr 2022, at 16:21, Michael A Spall <mspall at whoi.edu> wrote:
> 
> I am interested in making my linear bottom drag coefficient a function of space. I tried to do this
> by defining a 2-D array between 0 and 1 and multiplying the rhs of uDragTerms in mom_u_bottomdrag.F
> by this scaling array (same for vDragTerms in mom_v_bottomdrag.F). I added common blocks to those
> subroutines with the array so it is seen there. However, it looks like bi and bj are both 1 for all tiles in those
> subtroutines, so it always takes the values of my scaling array from the first tile.  Also in dynamics.F, which
> calls them. I found some text online that says these are done in dynamics.F by a single loop, but I don't know
> what that means.  Any advice on how to make bottom drag a function of location? 
> 
> I am using MITgcm_c65l, the SIZE.h file is below.
> 
> Thanks,
> Mike
> 
> C $Header: /u/gcmpack/MITgcm/model/inc/SIZE.h,v 1.28 2009/05/17 21:15:07 jmc Exp $
> C $Name:  $
> C
> CBOP
> C    !ROUTINE: SIZE.h
> C    !INTERFACE:
> C    include SIZE.h
> C    !DESCRIPTION: \bv
> C     *==========================================================*
> C     | SIZE.h Declare size of underlying computational grid.     
> C     *==========================================================*
> C     | The design here support a three-dimensional model grid    
> C     | with indices I,J and K. The three-dimensional domain      
> C     | is comprised of nPx*nSx blocks of size sNx along one axis 
> C     | nPy*nSy blocks of size sNy along another axis and one     
> C     | block of size Nz along the final axis.                    
> C     | Blocks have overlap regions of size OLx and OLy along the 
> C     | dimensions that are subdivided.                           
> C     *==========================================================*
> C     \ev
> CEOP
> C     Voodoo numbers controlling data layout.
> C     sNx :: No. X points in sub-grid.
> C     sNy :: No. Y points in sub-grid.
> C     OLx :: Overlap extent in X.
> C     OLy :: Overlat extent in Y.
> C     nSx :: No. sub-grids in X.
> C     nSy :: No. sub-grids in Y.
> C     nPx :: No. of processes to use in X.
> C     nPy :: No. of processes to use in Y.
> C     Nx  :: No. points in X for the total domain.
> C     Ny  :: No. points in Y for the total domain.
> C     Nr  :: No. points in Z for full process domain.
>      INTEGER sNx
>      INTEGER sNy
>      INTEGER OLx
>      INTEGER OLy
>      INTEGER nSx
>      INTEGER nSy
>      INTEGER nPx
>      INTEGER nPy
>      INTEGER Nx
>      INTEGER Ny
>      INTEGER Nr
>      PARAMETER (
>     &           sNx = 35,
>     &           sNy = 35,
>     &           OLx =   4,
>     &           OLy =   4,
>     &           nSx =   1,
>     &           nSy =   1,
>     &           nPx =  12,
>     &           nPy =  12,
>     &           Nx  = sNx*nSx*nPx,
>     &           Ny  = sNy*nSy*nPy,
>     &           Nr  =  60)
> 
> C     MAX_OLX :: Set to the maximum overlap region size of any array
> C     MAX_OLY    that will be exchanged. Controls the sizing of exch
> C                routine buffers.
>      INTEGER MAX_OLX
>      INTEGER MAX_OLY
>      PARAMETER ( MAX_OLX = OLx,
>     &            MAX_OLY = OLy )
> 
> 
> 
> ==================================================================
> 
> Michael A. Spall
> Senior Scientist
> Clark 323A
> Department of Physical Oceanography
> Woods Hole Oceanographic Institution
> 360 Woods Hole Road MS #21
> Woods Hole, MA 02543
> 
> 508-289-3342
> mspall at whoi.edu
> https://www2.whoi.edu/staff/mspall
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support

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