[MITgcm-support] spatially variable bottom drag

[Michael A Spall]

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