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C $Header: /u/gcmpack/MITgcm/pkg/generic_advdiff/gad_dst2u1_adv_r.F,v 1.2 2006/06/12 16:06:28 jmc Exp $ |
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C $Name: $ |
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|
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#include "GAD_OPTIONS.h" |
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|
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CBOP |
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C !ROUTINE: GAD_DST2U1_ADV_R |
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|
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C !INTERFACE: ========================================================== |
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SUBROUTINE GAD_DST2U1_ADV_R( |
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I bi,bj,k, advectionScheme, |
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I deltaTloc, rTrans, wFld, |
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I tracer, |
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O wT, |
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I myThid ) |
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|
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C !DESCRIPTION: |
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C Calculates the area integrated vertical flux due to advection |
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C of a tracer using second-order Direct Space and Time (DST-2) |
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C interpolation (=Lax-Wendroff) or simple 1rst order upwind scheme. |
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|
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C !USES: =============================================================== |
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IMPLICIT NONE |
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#include "SIZE.h" |
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#include "GRID.h" |
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#include "GAD.h" |
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|
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C !INPUT PARAMETERS: =================================================== |
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C bi,bj :: tile indices |
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C k :: vertical level |
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C advectionScheme :: advection scheme to use: either 2nd Order DST |
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C or 1rst Order Upwind |
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C deltaTloc :: local time-step (s) |
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C rTrans :: vertical volume transport |
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C wFld :: vertical flow |
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C tracer :: tracer field |
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C myThid :: thread number |
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INTEGER bi,bj,k |
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INTEGER advectionScheme |
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_RL deltaTloc |
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_RL rTrans(1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RL wFld (1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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_RL tracer(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr) |
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INTEGER myThid |
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|
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C !OUTPUT PARAMETERS: ================================================== |
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C wT :: vertical advective flux |
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_RL wT (1-OLx:sNx+OLx,1-OLy:sNy+OLy) |
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|
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C !LOCAL VARIABLES: ==================================================== |
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C i,j :: loop indices |
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C km1 :: =max( k-1 , 1 ) |
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C rLimit :: centered (vs upwind) fraction |
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C wLoc :: velocity, vertical component |
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C wCFL :: Courant-Friedrich-Levy number |
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INTEGER i,j,km1 |
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_RL wLoc, wCFL, rLimit, wAbs |
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CEOP |
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|
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rLimit = 0. _d 0 |
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IF ( advectionScheme.EQ.ENUM_DST2 ) rLimit = 1. _d 0 |
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|
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km1=MAX(1,k-1) |
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|
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IF ( k.LE.1 .OR. k.GT.Nr) THEN |
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DO j=1-Oly,sNy+Oly |
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DO i=1-Olx,sNx+Olx |
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wT(i,j) = 0. |
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ENDDO |
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ENDDO |
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ELSE |
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DO j=1-Oly,sNy+Oly |
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DO i=1-Olx,sNx+Olx |
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|
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c wLoc = wFld(i,j) |
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wLoc = rTrans(i,j)*recip_rA(i,j,bi,bj) |
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wCFL = ABS(wLoc*deltaTloc*recip_drC(k)) |
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|
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c wT(i,j) = maskC(i,j,km1,bi,bj)*( |
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c & rTrans(i,j)*(tracer(i,j,km1)+tracer(i,j,k))*0.5 _d 0 |
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c & + ( 1. _d 0 - rLimit*(1. _d 0 - wCFL) )*ABS(rTrans(i,j)) |
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c & *(tracer(i,j,km1)-tracer(i,j,k))*0.5 _d 0*rkSign |
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c & ) |
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C-- above formulation produces large truncation error when: |
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C 1rst.O upWind and w*rkSign > 0 & |tracer(k-1)| << |tracer(k)| |
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C or w*rkSign < 0 & |tracer(k-1)| >> |tracer(k)| |
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C-- change to a more robust expression: |
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wAbs = ABS(rTrans(i,j))*rkSign |
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& *( 1. _d 0 - rLimit*(1. _d 0 - wCFL) ) |
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wT(i,j) = maskC(i,j,km1,bi,bj)*( |
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& ( rTrans(i,j)+wAbs )* 0.5 _d 0 * tracer(i,j,km1) |
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& + ( rTrans(i,j)-wAbs )* 0.5 _d 0 * tracer(i,j,k) |
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& ) |
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ENDDO |
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ENDDO |
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ENDIF |
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|
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RETURN |
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END |
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