    SUBROUTINE DIVHOA
!     ******************************************************************
!$$$  SUBPROGRAM DOCUMENTATION BLOCK
!                .      .    .
! SUBPROGRAM:    DIVHOA      DIVERGENCE/HORIZONTAL OMEGA-ALPHA
!   PRGRMMR: JANJIC          ORG: W/NP22     DATE: 93-10-28

! ABSTRACT:
!     DIVHOA COMPUTES THE DIVERGENCE INCLUDING THE
!     MODIFICATION PREVENTING GRAVITY WAVE GRID SEPARATION, AND
!     CALCULATES THE HORIZONTAL PART OF THE OMEGA-ALPHA TERM
!     (THE PART PROPORTIONAL TO THE ADVECTION OF MASS ALONG
!     ETA/SIGMA SURFACES).

! PROGRAM HISTORY LOG:
!   87-06-??  JANJIC     - ORIGINATOR
!   95-03-25  BLACK      - CONVERSION FROM 1-D TO 2-D IN HORIZONTAL
!   96-03-29  BLACK      - ADDED EXTERNAL EDGE
!   97-03-17  MESINGER   - SPLIT FROM PFDHT
!   98-10-30  BLACK      - MODIFIED FOR DISTRIBUTED MEMORY
!   00-10-20  BLACK      - INCORPORATED PRESSURE GRADIENT METHOD
!                          FROM MESO MODEL

! USAGE: CALL DIVHOA FROM MAIN PROGRAM EBU
!   INPUT ARGUMENT LIST:
!       NONE

!   OUTPUT ARGUMENT LIST:
!     NONE

!   OUTPUT FILES:
!     NONE

!   SUBPROGRAMS CALLED:

!     UNIQUE: NONE

!     LIBRARY: NONE

!   COMMON BLOCKS: CTLBLK
!                  MASKS
!                  LOOPS
!                  DYNAM
!                  VRBLS
!                  CONTIN
!                  INDX

! ATTRIBUTES:
!   LANGUAGE: FORTRAN 90
!   MACHINE : IBM SP
!$$$
!***********************************************************************
!-----------------------------------------------------------------------
    INCLUDE "parmeta.f90"
    INCLUDE "mpp.h"
!-----------------------------------------------------------------------
    PARAMETER &
    (LP1=LM+1,JAM=6+2*(JM-10))
!-----------------------------------------------------------------------
    LOGICAL :: &
    RUN,FIRST,RESTRT,SIGMA
!----------------------------------------------------------------------
    INCLUDE "COMM_CTLBLK.f90"
!-----------------------------------------------------------------------
    include "COMM_LOOPS.f90"
!-----------------------------------------------------------------------
    INCLUDE "COMM_MASKS.f90"
!-----------------------------------------------------------------------
    INCLUDE "COMM_INDX.f90"
!-----------------------------------------------------------------------
    INCLUDE "COMM_DYNAM.f90"
!-----------------------------------------------------------------------
    INCLUDE "COMM_VRBLS.f90"
!-----------------------------------------------------------------------
    INCLUDE "COMM_CONTIN.f90"
!-----------------------------------------------------------------------
    INCLUDE "COMM_NHYDRO.f90"
!-----------------------------------------------------------------------
    INCLUDE "COMM_CLDWTR.f90"
!-----------------------------------------------------------------------
    REAL :: &
    PINTLG(IDIM1:IDIM2,JDIM1:JDIM2,LM+1)

    REAL :: &
    FIM   (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,FILO  (IDIM1:IDIM2,JDIM1:JDIM2),RDPD  (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,ADPDX (IDIM1:IDIM2,JDIM1:JDIM2),RDPDX (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,ADPDY (IDIM1:IDIM2,JDIM1:JDIM2),RDPDY (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,ADPDNE(IDIM1:IDIM2,JDIM1:JDIM2),ADPDSE(IDIM1:IDIM2,JDIM1:JDIM2) &
    ,PEW   (IDIM1:IDIM2,JDIM1:JDIM2),PNS   (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,PCEW  (IDIM1:IDIM2,JDIM1:JDIM2),PCNS  (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,DPFEW (IDIM1:IDIM2,JDIM1:JDIM2),DPFNS (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,FNS   (IDIM1:IDIM2,JDIM1:JDIM2),TNS   (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,HM    (IDIM1:IDIM2,JDIM1:JDIM2),VM    (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,EDIV  (IDIM1:IDIM2,JDIM1:JDIM2),DIVL  (IDIM1:IDIM2,JDIM1:JDIM2)

    REAL :: &
    DPDE  (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,APEL  (IDIM1:IDIM2,JDIM1:JDIM2),PCXC  (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,ALP1  (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,DFDZ  (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,UDY   (IDIM1:IDIM2,JDIM1:JDIM2),VDX   (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,TEW   (IDIM1:IDIM2,JDIM1:JDIM2),FEW   (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,TNE   (IDIM1:IDIM2,JDIM1:JDIM2),TSE   (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,FNE   (IDIM1:IDIM2,JDIM1:JDIM2),FSE   (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,PNE   (IDIM1:IDIM2,JDIM1:JDIM2),PSE   (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,CNE   (IDIM1:IDIM2,JDIM1:JDIM2),CSE   (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,PPNE  (IDIM1:IDIM2,JDIM1:JDIM2),PPSE  (IDIM1:IDIM2,JDIM1:JDIM2) &
    ,PCNE  (IDIM1:IDIM2,JDIM1:JDIM2),PCSE  (IDIM1:IDIM2,JDIM1:JDIM2)
!-----------------------------------------------------------------------
!-----------------------------------------------------------------------
    CALL ZERO2(ALP1)
    CALL ZERO2(DPDE)
    CALL ZERO2(APEL)
    CALL ZERO2(PCXC)
    CALL ZERO2(DFDZ)
    CALL ZERO2(UDY)
    CALL ZERO2(VDX)
    CALL ZERO2(TEW)
    CALL ZERO2(FEW)
    CALL ZERO2(TNE)
    CALL ZERO2(TSE)
    CALL ZERO2(FNE)
    CALL ZERO2(FSE)
    CALL ZERO2(PNE)
    CALL ZERO2(PSE)
    CALL ZERO2(CNE)
    CALL ZERO2(CSE)
    CALL ZERO2(PPNE)
    CALL ZERO2(PPSE)
    CALL ZERO2(PCNE)
    CALL ZERO2(PCSE)
!-----------------------------------------------------------------------
!--------------PREPARATORY CALCULATIONS---------------------------------
!-----------------------------------------------------------------------
    IF(SIGMA)THEN
    ! omp parallel do
        DO 50 J=MYJS_P5,MYJE_P5
            DO 50 I=MYIS_P5,MYIE_P5
                FILO(I,J)=FIS(I,J)
                PDSL(I,J)=PD(I,J)
        50 END DO
    ELSE
    ! omp parallel do
        DO 100 J=MYJS_P5,MYJE_P5
            DO 100 I=MYIS_P5,MYIE_P5
                FILO(I,J)=0.0
                PDSL(I,J)=RES(I,J)*PD(I,J)
        100 END DO
    ENDIF

    IF(HYDRO)THEN
    ! omp parallel do
        DO L=1,LM+1
            DO J=MYJS_P5,MYJE_P5
                DO I=MYIS_P5,MYIE_P5
                    PINTLG(I,J,L)=ALOG(ETA(L)*PDSL(I,J)+PT)
                ENDDO
            ENDDO
        ENDDO
    ELSE
    ! omp parallel do
        DO L=1,LM+1
            DO J=MYJS_P5,MYJE_P5
                DO I=MYIS_P5,MYIE_P5
                    PINTLG(I,J,L)=ALOG(PINT(I,J,L))
                ENDDO
            ENDDO
        ENDDO
    ENDIF

! omp parallel do
    DO L=1,LM
        DO J=MYJS_P4,MYJE_P4
            DO I=MYIS_P4,MYIE_P4
                OMGALF(I,J,L)=0.
                DIV(I,J,L)=0.
            ENDDO
        ENDDO
    ENDDO
!-----------------------------------------------------------------------
! omp parallel do private (alp1x)
    DO J=MYJS_P5,MYJE_P5
        DO I=MYIS_P5,MYIE_P5
            ALP1X=PINTLG(I,J,LM+1)
            ALP1(I,J)=ALP1X
        ENDDO
    ENDDO
!-----------------------------------------------------------------------
!-------------------- MAIN VERTICAL INTEGRATION LOOP -------------------
!-----------------------------------------------------------------------
    DO 400 L=LM,1,-1
    !-----------------------------------------------------------------------
    !***
    !***  INTEGRATE THE GEOPOTENTIAL
    !***
    ! p
        FIM=0.
    ! p
    
    ! omp parallel do private (alp1p,dfi,fiupk,rdpds)
    !       write(6,*) 'FIM defined over I: ', MYIS_P5,MYIE_P5
    !       write(6,*) 'FIM defined over J: ', MYJS_P5,MYJE_P5
        DO 125 J=MYJS_P5,MYJE_P5
            DO 125 I=MYIS_P5,MYIE_P5
            
                ALP1P=PINTLG(I,J,L)
            
            ! ule      DFI=(Q(I,J,L)*0.608+1.)*T(I,J,L)*R*(ALP1(I,J)-ALP1P)/DWDT(I,J,L)
                DFI=(Q(I,J,L)*0.608+1.)*T(I,J,L)*R*(ALP1(I,J)-ALP1P) &
                /(1+CWM(I,J,L))/DWDT(I,J,L)
            
                RDPDS=1./(DETA(L)*PDSL(I,J))
                RTOP(I,J,L)=RDPDS*DFI
                FIUPK=FILO(I,J)+DFI
                FIM(I,J)=FILO(I,J)+FIUPK
                if (abs(FIM(I,J)) <= 5.e+10) then
                else
                    write(6,*) 'bad FIM ', I,J,FIM(I,J),FILO(I,J),DFI
                    write(6,*) 'Q,T,ALP1,ALP1P,DWDT: ', &
                    Q(I,J,L),T(I,J,L),ALP1(I,J),ALP1P,DWDT(I,J,L)
                    STOP
                endif
            
                FILO(I,J)=(FIUPK-DFL(L))*HTM(I,J,L)+DFL(L)
                ALP1(I,J)=ALP1P
        125 END DO
    
    !-----------------------------------------------------------------------
    ! omp parallel do private (alp1p,alp1pl,alp2p,alp2pl,dfi)
        DO 205 J=MYJS_P5,MYJE_P5
            DO 205 I=MYIS_P5,MYIE_P5
                HM(I,J)=HTM(I,J,L)*HBM2(I,J)
                VM(I,J)=VTM(I,J,L)*VBM2(I,J)
            
                ALP1P =PINTLG(I,J,L)
                ALP1PL=PINTLG(I,J,L+1)
                ALP2P =ALP1P*ALP1P
                ALP2PL=ALP1PL*ALP1PL
            
            ! ule      DFI=(Q(I,J,L)*0.608+1.)*T(I,J,L)*R*(ALP1PL-ALP1P)/DWDT(I,J,L)
                DFI=(Q(I,J,L)*0.608+1.)*T(I,J,L)*R*(ALP1PL-ALP1P) &
                /(1+CWM(I,J,L))/DWDT(I,J,L)
                DFDZ(I,J)=DFI*DWDT(I,J,L)/(ALP2PL-ALP2P)
                APEL(I,J)=(ALP2PL+ALP2P)*0.5
        205 END DO
    
    ! omp parallel do
        DO 210 J=MYJS_P4,MYJE_P4
            DO 210 I=MYIS_P4,MYIE_P4
                DPDE(I,J)=DETA(L)*PDSL(I,J)
                DIVL(I,J)=0.
                EDIV(I,J)=0.
        210 END DO
    
    ! omp parallel do
        DO 215 J=MYJS_P1,MYJE_P1
            DO 215 I=MYIS_P1,MYIE_P1
                RDPD(I,J)=1./DPDE(I,J)
        215 END DO
    
    ! omp parallel do
        DO 220 J=MYJS1_P3,MYJE1_P3
            DO 220 I=MYIS_P3,MYIE_P3
                ADPDX(I,J)=DPDE(I+IVW(J),J)+DPDE(I+IVE(J),J)
                ADPDY(I,J)=DPDE(I,J-1)+DPDE(I,J+1)
                RDPDX(I,J)=1./ADPDX(I,J)
                RDPDY(I,J)=1./ADPDY(I,J)
        220 END DO
    
    !--------------DIAGONAL CONTRIBUTIONS TO PRESSURE GRADIENT FORCE--------
    
    ! omp parallel do
        DO 240 J=MYJS_P4,MYJE_P4
            DO 240 I=MYIS_P4,MYIE_P4
                ADPDNE(I,J)=DPDE(I+IHE(J),J+1)+DPDE(I,J)
                PNE(I,J)=(FIM (I+IHE(J),J+1)-FIM (I,J)) &
                *(DWDT(I+IHE(J),J+1,L)+DWDT(I,J,L))
                if ( ABS(PNE(I,J)) <= 5.e10) then
                else
                    write(6,*) 'crazy PNE ',I,J,PNE(I,J)
                    write(6,*) 'pieces', I+IHE(J),J+1,FIM (I+IHE(J),J+1)
                endif
                PPNE(I,J)=PNE(I,J)*ADPDNE(I,J)
                CNE(I,J)=(DFDZ(I+IHE(J),J+1)+DFDZ(I,J))*2. &
                *(APEL(I+IHE(J),J+1)-APEL(I,J))
                PCNE(I,J)=CNE(I,J)*ADPDNE(I,J)
        240 END DO
    
    ! omp parallel do
        DO 250 J=MYJS1_P4,MYJE_P4
            DO 250 I=MYIS_P4,MYIE1_P4
                ADPDSE(I,J)=DPDE(I+IHE(J),J-1)+DPDE(I,J)
                PSE(I,J)=(FIM(I+IHE(J),J-1)-FIM(I,J)) &
                *(DWDT(I+IHE(J),J-1,L)+DWDT(I,J,L))
                PPSE(I,J)=PSE(I,J)*ADPDSE(I,J)
                CSE(I,J)=(DFDZ(I+IHE(J),J-1)+DFDZ(I,J))*2. &
                *(APEL(I+IHE(J),J-1)-APEL(I,J))
                PCSE(I,J)=CSE(I,J)*ADPDSE(I,J)
        250 END DO
    
    !--------------CONTINUITY EQUATION MODIFICATION-------------------------
    
    ! omp parallel do
        DO 260 J=MYJS1_P1,MYJE1_P1
            DO 260 I=MYIS_P1,MYIE_P1
                PCXC(I,J)=VBM3(I,J)*VTM(I,J,L)*(PNE(I+IVW(J),J) &
                +CNE(I+IVW(J),J)+PSE(I+IVW(J),J)+CSE(I+IVW(J),J) &
                -PNE(I,J-1)-CNE(I,J-1)-PSE(I,J+1)-CSE(I,J+1))
        260 END DO
    !-----------------------------------------------------------------------
        DO 270 J=MYJS2,MYJE2
            DO 270 I=MYIS1,MYIE1
                DIV(I,J,L)=DETA(L)*WPDAR(I,J) &
                *(PCXC(I+IHE(J),J)-PCXC(I,J+1) &
                +PCXC(I+IHW(J),J)-PCXC(I,J-1))
        270 END DO
    
    !--------------LAT & LONG PRESSURE FORCE COMPONENTS---------------------
    
    ! omp parallel do private (dcnek,dcsek,dpnek,dpsek)
        DO 280 J=MYJS1_P3,MYJE1_P3
            DO 280 I=MYIS_P3,MYIE_P3
                DPNEK=PNE(I+IVW(J),J)+PNE(I,J-1)
                DPSEK=PSE(I+IVW(J),J)+PSE(I,J+1)
                PEW(I,J)=DPNEK+DPSEK
                PNS(I,J)=DPNEK-DPSEK
                DCNEK=CNE(I+IVW(J),J)+CNE(I,J-1)
                DCSEK=CSE(I+IVW(J),J)+CSE(I,J+1)
                PCEW(I,J)=(DCNEK+DCSEK)*ADPDX(I,J)
                PCNS(I,J)=(DCNEK-DCSEK)*ADPDY(I,J)
        280 END DO
    
    !--------------LAT & LON FLUXES & OMEGA-ALPHA COMPONENTS----------------
    
    ! omp parallel do
        DO 310 J=MYJS1_P3,MYJE1_P3
            DO 310 I=MYIS_P3,MYIE_P3
                UDY(I,J)=DY*U(I,J,L)
                FEW(I,J)=UDY(I,J)*ADPDX(I,J)
                TEW(I,J)=UDY(I,J)*PCEW(I,J)
                VDX(I,J)=DX(I,J)*V(I,J,L)
                FNS(I,J)=VDX(I,J)*ADPDY(I,J)
                TNS(I,J)=VDX(I,J)*PCNS(I,J)
        310 END DO
    
    !--------------DIAGONAL FLUXES AND DIAGONALLY AVERAGED WIND-------------
    
    ! omp parallel do private (pvnek)
        DO 320 J=MYJS1_P2,MYJE2_P2
            DO 320 I=MYIS_P2,MYIE1_P2
                PVNEK=(UDY(I+IHE(J),J)+VDX(I+IHE(J),J))+(UDY(I,J+1)+VDX(I,J+1))
                FNE(I,J)=PVNEK*ADPDNE(I,J)
                TNE(I,J)=PVNEK*PCNE(I,J)*2.
        320 END DO
    
    ! omp parallel do private (pvsek)
        DO 330 J=MYJS2_P2,MYJE1_P2
            DO 330 I=MYIS_P2,MYIE1_P2
                PVSEK=(UDY(I+IHE(J),J)-VDX(I+IHE(J),J))+(UDY(I,J-1)-VDX(I,J-1))
                FSE(I,J)=PVSEK*ADPDSE(I,J)
                TSE(I,J)=PVSEK*PCSE(I,J)*2.
        330 END DO
    
    !--------------HORIZONTAL PART OF OMEGA-ALPHA & DIVERGENCE--------------
    
    ! omp parallel do
        DO 340 J=MYJS2_P1,MYJE2_P1
            DO 340 I=MYIS1_P1,MYIE1_P1
                OMGALF(I,J,L)=(TEW(I+IHE(J),J)+TEW(I+IHW(J),J)+TNS(I,J+1) &
                +TNS(I,J-1)+TNE(I,J)+TNE(I+IHW(J),J-1)+TSE(I,J) &
                +TSE(I+IHW(J),J+1))*RDPD(I,J)*FCP(I,J)*HM(I,J)
                T(I,J,L)=OMGALF(I,J,L)+T(I,J,L)
                EDIV(I,J)=((FEW(I+IHE(J),J)+FNS(I,J+1) &
                +FNE(I,J)+FSE(I,J)) &
                -(FEW(I+IHW(J),J)+FNS(I,J-1) &
                +FNE(I+IHW(J),J-1)+FSE(I+IHW(J),J+1)))*FDIV(I,J)
                DIVL(I,J)=EDIV(I,J)*HBM2(I,J)
        340 END DO
    
    !------------------------------------------------------------------------
    
    ! omp parallel do
        DO 390 J=MYJS,MYJE
            DO 390 I=MYIS,MYIE
                DIV(I,J,L)=(DIV(I,J,L)+DIVL(I,J))*HM(I,J)
        390 END DO
    !-----------------------------------------------------------------------
    400 END DO
!-----------------------------------------------------------------------
    RETURN
    END SUBROUTINE DIVHOA
