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!                     version 3; Last Modified: May 7, 2008.
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!

      subroutine adivbal(pgdpsi,pgdchi) 2
#if defined (DOC)
*
***s/r adivbal -Adjoint for construction of  grid-point balanced
*               divergence (vel. pot.)
*     .
* Purpose
*     .  Adjoint for balanced divergence (actually velocity potential) operator
*
*Author  : Mark Buehner *ARMA/AES  August, 1998
*
*Revision :
*         C. Charette - ARMA/SMC - Sept 2004
*          - Conversion to hybrid vertical coordinate
*            New variable nlev_bdl
*Arguments
*
* In
*    pgdpsi : Grid-point del(PSI)*
*    pgdchi : Grid-point del(CHI)*
* Out
*    pgdpsi : Grid-point total del(PSI)*
*     .
*Revision:
#endif
C
      IMPLICIT NONE
#include "pardim.cdk"
#include "comdim.cdk"
#include "comgem.cdk"
#include "comcorr.cdk"
C
      INTEGER ILON, JK1, JLON, JLAT
      REAL*8 ZFACT
      REAL*8 pgdpsi(NIBEG:NIEND,nflev,NJBEG:NJEND)
      REAL*8 pgdchi(NIBEG:NIEND,nflev,NJBEG:NJEND)
c
c
      DO JLAT = 1, NJ
        ILON = NILON(JLAT)
        do jk1=nlev_bdl,NFLEV
          zfact=-tan(THETA(jk1,jlat))
          DO JLON = 1, ILON
            pGDPSI(jlon,jk1,jlat)=pGDPSI(jlon,jk1,jlat) +
     +                      zfact*pGDCHI(jlon,jk1,jlat)
          enddo
        END DO
      END DO
c
      RETURN
      END