C $Header: /u/gcmpack/MITgcm/pkg/generic_advdiff/gad_grad_x.F,v 1.10 2011/03/29 15:53:45 jmc Exp $ C $Name: $ #include "GAD_OPTIONS.h" CBOP C !ROUTINE: GAD_GRAD_X C !INTERFACE: ========================================================== SUBROUTINE GAD_GRAD_X( I bi,bj,k, I xA, U tracer, O dTdx, I myThid ) C !DESCRIPTION: C Calculates the zonal gradient of a tracer: $\partial_x \theta C = \frac{1}{\Delta x_c} \delta_i \theta$ C and multiplies by the area. C !USES: =============================================================== IMPLICIT NONE #include "SIZE.h" #include "EEPARAMS.h" #include "GRID.h" C !INPUT PARAMETERS: =================================================== C bi,bj :: tile indices C k :: vertical level C myThid :: thread number INTEGER bi,bj,k _RS xA (1-OLx:sNx+OLx,1-OLy:sNy+OLy) INTEGER myThid C !UPDATED PARAMETERS: ================================================= C tracer :: tracer field C (NOTE: only udate the corner-halo region when using CS-grid) _RL tracer(1-OLx:sNx+OLx,1-OLy:sNy+OLy) C !OUTPUT PARAMETERS: ================================================== C dTdx :: zonal gradient (units = [Tr_units]*[r_units]) _RL dTdx (1-OLx:sNx+OLx,1-OLy:sNy+OLy) C !LOCAL VARIABLES: ==================================================== C i,j :: loop indices INTEGER i,j CEOP cph-exch2#ifndef ALLOW_AUTODIFF_TAMC C-- Internal exchange for calculations in X IF (useCubedSphereExchange) THEN CALL FILL_CS_CORNER_TR_RL( 1, .FALSE., & tracer, bi,bj, myThid ) ENDIF cph-exch2#endif C o Zonal tracer gradient DO j=1-Oly,sNy+Oly dTdx(1-Olx,j)=0. DO i=1-Olx+1,sNx+Olx dTdx(i,j) = xA(i,j) & *_recip_dxC(i,j,bi,bj)*recip_deepFacC(k) & *(tracer(i,j)-tracer(i-1,j)) #ifdef COSINEMETH_III & *sqCosFacU(j,bi,bj) #endif #ifdef ALLOW_OBCS & *maskInW(i,j,bi,bj) #endif ENDDO ENDDO RETURN END