C $Header: /u/gcmpack/MITgcm/model/src/ini_cartesian_grid.F,v 1.22 2010/04/17 18:25:12 jmc Exp $
C $Name: $
c#include "PACKAGES_CONFIG.h"
#include "CPP_OPTIONS.h"
CBOP
C !ROUTINE: INI_CARTESIAN_GRID
C !INTERFACE:
SUBROUTINE INI_CARTESIAN_GRID( myThid )
C !DESCRIPTION: \bv
C *==========================================================*
C | SUBROUTINE INI_CARTESIAN_GRID
C | o Initialise model coordinate system
C *==========================================================*
C | The grid arrays, initialised here, are used throughout
C | the code in evaluating gradients, integrals and spatial
C | avarages. This routine
C | is called separately by each thread and initialises only
C | the region of the domain it is "responsible" for.
C | Notes:
C | Two examples are included. One illustrates the
C | initialisation of a cartesian grid (this routine).
C | The other shows the
C | inialisation of a spherical polar grid. Other orthonormal
C | grids can be fitted into this design. In this case
C | custom metric terms also need adding to account for the
C | projections of velocity vectors onto these grids.
C | The structure used here also makes it possible to
C | implement less regular grid mappings. In particular
C | o Schemes which leave out blocks of the domain that are
C | all land could be supported.
C | o Multi-level schemes such as icosohedral or cubic
C | grid projections onto a sphere can also be fitted
C | within the strategy we use.
C | Both of the above also require modifying the support
C | routines that map computational blocks to simulation
C | domain blocks.
C | Under the cartesian grid mode primitive distances in X
C | and Y are in metres. Disktance in Z are in m or Pa
C | depending on the vertical gridding mode.
C *==========================================================*
C \ev
C !USES:
IMPLICIT NONE
C === Global variables ===
#include "SIZE.h"
#include "EEPARAMS.h"
#include "PARAMS.h"
#include "GRID.h"
c#ifdef ALLOW_EXCH2
c#include "W2_EXCH2_SIZE.h"
c#include "W2_EXCH2_TOPOLOGY.h"
c#include "W2_EXCH2_PARAMS.h"
c#endif /* ALLOW_EXCH2 */
C !INPUT/OUTPUT PARAMETERS:
C == Routine arguments ==
C myThid :: Number of this instance of INI_CARTESIAN_GRID
INTEGER myThid
C !LOCAL VARIABLES:
C == Local variables ==
INTEGER iG, jG, bi, bj, i, j
_RL xG0, yG0
C "Long" real for temporary coordinate calculation
C NOTICE the extended range of indices!!
_RL xGloc(1-Olx:sNx+Olx+1,1-Oly:sNy+Oly+1)
_RL yGloc(1-Olx:sNx+Olx+1,1-Oly:sNy+Oly+1)
C These functions return the "global" index with valid values beyond
C halo regions
INTEGER iGl,jGl
iGl(i,bi) = 1+MOD(myXGlobalLo-1+(bi-1)*sNx+i+Olx*Nx-1,Nx)
jGl(j,bj) = 1+MOD(myYGlobalLo-1+(bj-1)*sNy+j+Oly*Ny-1,Ny)
c#ifdef ALLOW_EXCH2
c INTEGER tN
c#endif /* ALLOW_EXCH2 */
CEOP
C For each tile ...
DO bj = myByLo(myThid), myByHi(myThid)
DO bi = myBxLo(myThid), myBxHi(myThid)
C-- "Global" index (place holder)
jG = myYGlobalLo + (bj-1)*sNy
iG = myXGlobalLo + (bi-1)*sNx
c#ifdef ALLOW_EXCH2
c IF ( W2_useE2ioLayOut ) THEN
cC- note: does not work for non-uniform delX or delY
c tN = W2_myTileList(bi,bj)
c iG = exch2_txGlobalo(tN)
c jG = exch2_tyGlobalo(tN)
c ENDIF
c#endif /* ALLOW_EXCH2 */
C-- First find coordinate of tile corner (meaning outer corner of halo)
xG0 = xgOrigin
C Find the X-coordinate of the outer grid-line of the "real" tile
DO i=1, iG-1
xG0 = xG0 + delX(i)
ENDDO
C Back-step to the outer grid-line of the "halo" region
DO i=1, Olx
xG0 = xG0 - delX( 1+MOD(Olx*Nx-1+iG-i,Nx) )
ENDDO
C Find the Y-coordinate of the outer grid-line of the "real" tile
yG0 = ygOrigin
DO j=1, jG-1
yG0 = yG0 + delY(j)
ENDDO
C Back-step to the outer grid-line of the "halo" region
DO j=1, Oly
yG0 = yG0 - delY( 1+MOD(Oly*Ny-1+jG-j,Ny) )
ENDDO
C-- Calculate coordinates of cell corners for N+1 grid-lines
DO j=1-Oly,sNy+Oly +1
xGloc(1-Olx,j) = xG0
DO i=1-Olx,sNx+Olx
c xGloc(i+1,j) = xGloc(i,j) + delX(1+mod(Nx-1+iG-1+i,Nx))
xGloc(i+1,j) = xGloc(i,j) + delX( iGl(i,bi) )
ENDDO
ENDDO
DO i=1-Olx,sNx+Olx +1
yGloc(i,1-Oly) = yG0
DO j=1-Oly,sNy+Oly
c yGloc(i,j+1) = yGloc(i,j) + delY(1+mod(Ny-1+jG-1+j,Ny))
yGloc(i,j+1) = yGloc(i,j) + delY( jGl(j,bj) )
ENDDO
ENDDO
C-- Make a permanent copy of [xGloc,yGloc] in [xG,yG]
DO j=1-Oly,sNy+Oly
DO i=1-Olx,sNx+Olx
xG(i,j,bi,bj) = xGloc(i,j)
yG(i,j,bi,bj) = yGloc(i,j)
ENDDO
ENDDO
C-- Calculate [xC,yC], coordinates of cell centers
DO j=1-Oly,sNy+Oly
DO i=1-Olx,sNx+Olx
C by averaging
xC(i,j,bi,bj) = 0.25 _d 0*(
& xGloc(i,j)+xGloc(i+1,j)+xGloc(i,j+1)+xGloc(i+1,j+1) )
yC(i,j,bi,bj) = 0.25 _d 0*(
& yGloc(i,j)+yGloc(i+1,j)+yGloc(i,j+1)+yGloc(i+1,j+1) )
ENDDO
ENDDO
C-- Calculate [dxF,dyF], lengths between cell faces (through center)
DO j=1-Oly,sNy+Oly
DO i=1-Olx,sNx+Olx
dxF(i,j,bi,bj) = delX( iGl(i,bi) )
dyF(i,j,bi,bj) = delY( jGl(j,bj) )
ENDDO
ENDDO
C-- Calculate [dxG,dyG], lengths along cell boundaries
DO j=1-Oly,sNy+Oly
DO i=1-Olx,sNx+Olx
dxG(i,j,bi,bj) = delX( iGl(i,bi) )
dyG(i,j,bi,bj) = delY( jGl(j,bj) )
ENDDO
ENDDO
C-- The following arrays are not defined in some parts of the halo
C region. We set them to zero here for safety. If they are ever
C referred to, especially in the denominator then it is a mistake!
DO j=1-Oly,sNy+Oly
DO i=1-Olx,sNx+Olx
dxC(i,j,bi,bj) = 0.
dyC(i,j,bi,bj) = 0.
dxV(i,j,bi,bj) = 0.
dyU(i,j,bi,bj) = 0.
rAw(i,j,bi,bj) = 0.
rAs(i,j,bi,bj) = 0.
ENDDO
ENDDO
C-- Calculate [dxC], zonal length between cell centers
DO j=1-Oly,sNy+Oly
DO i=1-Olx+1,sNx+Olx ! NOTE range
dxC(i,j,bi,bj) = 0.5 _d 0*(dxF(i,j,bi,bj)+dxF(i-1,j,bi,bj))
ENDDO
ENDDO
C-- Calculate [dyC], meridional length between cell centers
DO j=1-Oly+1,sNy+Oly ! NOTE range
DO i=1-Olx,sNx+Olx
dyC(i,j,bi,bj) = 0.5 _d 0*(dyF(i,j,bi,bj)+dyF(i,j-1,bi,bj))
ENDDO
ENDDO
C-- Calculate [dxV,dyU], length between velocity points (through corners)
DO j=1-Oly+1,sNy+Oly ! NOTE range
DO i=1-Olx+1,sNx+Olx ! NOTE range
C by averaging (method I)
dxV(i,j,bi,bj) = 0.5 _d 0*(dxG(i,j,bi,bj)+dxG(i-1,j,bi,bj))
dyU(i,j,bi,bj) = 0.5 _d 0*(dyG(i,j,bi,bj)+dyG(i,j-1,bi,bj))
C by averaging (method II)
c dxV(i,j,bi,bj) = 0.5*(dxG(i,j,bi,bj)+dxG(i-1,j,bi,bj))
c dyU(i,j,bi,bj) = 0.5*(dyC(i,j,bi,bj)+dyC(i-1,j,bi,bj))
ENDDO
ENDDO
C-- Calculate vertical face area
DO j=1-Oly,sNy+Oly
DO i=1-Olx,sNx+Olx
rA (i,j,bi,bj) = dxF(i,j,bi,bj)*dyF(i,j,bi,bj)
rAw(i,j,bi,bj) = dxC(i,j,bi,bj)*dyG(i,j,bi,bj)
rAs(i,j,bi,bj) = dxG(i,j,bi,bj)*dyC(i,j,bi,bj)
rAz(i,j,bi,bj) = dxV(i,j,bi,bj)*dyU(i,j,bi,bj)
C-- Set trigonometric terms & grid orientation:
tanPhiAtU(i,j,bi,bj) = 0.
tanPhiAtV(i,j,bi,bj) = 0.
angleCosC(i,j,bi,bj) = 1.
angleSinC(i,j,bi,bj) = 0.
ENDDO
ENDDO
C-- Cosine(lat) scaling
DO j=1-OLy,sNy+OLy
cosFacU(j,bi,bj)=1.
cosFacV(j,bi,bj)=1.
sqcosFacU(j,bi,bj)=1.
sqcosFacV(j,bi,bj)=1.
ENDDO
C-- end bi,bj loops
ENDDO
ENDDO
C-- Set default (=whole domain) for where relaxation to climatology applies
_BEGIN_MASTER(myThid)
IF ( latBandClimRelax.EQ.UNSET_RL ) THEN
latBandClimRelax = 0.
DO j=1,Ny
latBandClimRelax = latBandClimRelax + delY(j)
ENDDO
latBandClimRelax = latBandClimRelax*3. _d 0
ENDIF
_END_MASTER(myThid)
RETURN
END