C $Header: /u/gcmpack/MITgcm/pkg/generic_advdiff/gad_c4_adv_y.F,v 1.6 2011/03/29 15:50:30 jmc Exp $ C $Name: $ #include "GAD_OPTIONS.h" CBOP C !ROUTINE: GAD_C4_ADV_Y C !INTERFACE: ========================================================== SUBROUTINE GAD_C4_ADV_Y( I bi,bj,k, I vTrans, maskLocS, I tracer, O vT, I myThid ) C !DESCRIPTION: C Calculates the area integrated meridional flux due to advection of a tracer C using centered fourth-order interpolation: C \begin{equation*} C F^y_{adv} = V \overline{ \theta - \frac{1}{6} \delta_{jj} \theta }^j C \end{equation*} C Near boundaries, the scheme reduces to a second if the flow is away C from the boundary and to third order if the flow is towards C the boundary. C !USES: =============================================================== IMPLICIT NONE #include "SIZE.h" #include "GRID.h" #include "GAD.h" C !INPUT PARAMETERS: =================================================== C bi,bj :: tile indices C k :: vertical level C vTrans :: meridional volume transport C maskLocS :: mask (either 0 or 1) at grid-cell southern edge C tracer :: tracer field C myThid :: my thread Id number INTEGER bi,bj,k _RL vTrans (1-OLx:sNx+OLx,1-OLy:sNy+OLy) _RS maskLocS(1-OLx:sNx+OLx,1-OLy:sNy+OLy) _RL tracer (1-OLx:sNx+OLx,1-OLy:sNy+OLy) INTEGER myThid C !OUTPUT PARAMETERS: ================================================== C uT :: zonal advective flux _RL vT (1-OLx:sNx+OLx,1-OLy:sNy+OLy) C !LOCAL VARIABLES: ==================================================== C i,j :: loop indices C Rjm,Rj,Rjp :: differences at j-1,j,j+1 C Rjjm,Rjjp :: second differences at j-1,j INTEGER i,j _RL Rjm,Rj,Rjp,Rjjm,Rjjp CEOP DO i=1-Olx,sNx+Olx vT(i,1-Oly)=0. vT(i,2-Oly)=0. vT(i,sNy+Oly)=0. ENDDO DO j=1-Oly+2,sNy+Oly-1 DO i=1-Olx,sNx+Olx Rjp = (tracer(i,j+1)-tracer(i, j ))*maskLocS(i,j+1) Rj = (tracer(i, j )-tracer(i,j-1))*maskLocS(i, j ) Rjm = (tracer(i,j-1)-tracer(i,j-2))*maskLocS(i,j-1) Rjjp=(Rjp-Rj) Rjjm=(Rj-Rjm) vT(i,j) = & vTrans(i,j)*( & Tracer(i,j)+Tracer(i,j-1)-oneSixth*( Rjjp+Rjjm ) & )*0.5 _d 0 & +ABS( vTrans(i,j) )*0.5 _d 0*oneSixth*( Rjjp-Rjjm ) & *( 1. _d 0 - maskS(i,j-1,k,bi,bj)*maskS(i,j+1,k,bi,bj) ) c & *( 1. _d 0 - maskLocS(i,j-1)*maskLocS(i,j+1) ) ENDDO ENDDO RETURN END