#include "dims.h"
      SUBROUTINE FLOWV3(IHEM)
      use cons_module,only: imax
      implicit none
!
! Args:
      integer,intent(out) :: IHEM
C     ****
C     ****     TRANSFORM TO AURORAL CIRCLE COORDINATES
C     ****
#include "params.h"
#include "cflowv3.h"
#include "phys.h"
      real :: cosofa,sinofa,aslona,pi,pi2
      COMMON /OVALPOS/ COSOFA(2),SINOFA(2),ASLONA(2),PI,PI2
      real :: rlatm,rlonm,dipmag,decmag,sndec,csdec,sn2dec,sncsdc,
     |  rlatmp,rlonmp,dlons
      COMMON/TRGM/RLATM(ZIMXP,ZJMX),RLONM(ZIMXP,ZJMX),
     1  DIPMAG(ZIMXP,ZJMX),DECMAG(ZIMXP,ZJMX),SNDEC(ZIMXP,ZJMX),
     2  CSDEC(ZIMXP,ZJMX),SN2DEC(ZIMXP,ZJMX),SNCSDC(ZIMXP,ZJMX),
     3  RLATMP(ZJMX),RLONMP(ZJMX),DLONS(ZJMX)
!
! Local:
      real :: dlat(zimx),dlon(zimx),ratio(zimx)
      integer :: i,imaxd2,iflag(zimx)
!
! dlat,dlon, ratio, and iflag are local.
!   rlatm, rlonm are in regular common /TRGM/ defined by magdyn.f 
!     (magdyn is called by main tgcm before advnce)
!   dlons is also in /TRGM/ and is defined in sunloc.f
!     (sunloc is called by advnce before main latitude loop)
!
      do i=1,imax
        dlat(i) = rlatm(i+2,j)
        dlon(i) = rlonm(i+2,j)-dlons(j)
        ratio(i) = 1.
        iflag(i) = 1
      enddo
C     ****               SET IHEM = 1,2  FOR  S,N HEMISPHERE
      IMAXD2 = MAX0(1,IMAX/2)
      IHEM = IFIX(DLAT(IMAXD2)*2./3.1416 + 2.)
C     ****
C     ****     TRANSFORM TO AURORAL CIRCLE CORDINATES
C     ****       I.E. CALCULATE COLAT AND ALON FOR POLHT AND AURHT
C     ****
!
! Define colat and alon (taskcommon in cflowv3.h) for polht and aurht:
!
      DO 8 I=1,IMAX
!
! Define sin/cos lat/lon in taskcommon /CFLOWV3/
        SINLAT(I)=SIN(ABS(DLAT(I)))
        COSLAT(I)=COS(DLAT(I))
        SINLON(I) = SIN(DLON(I)+ASLONA(IHEM))
        COSLON(I) = COS(DLON(I)+ASLONA(IHEM))
!
! colat and alon also in /CFLOWV3/
        COLAT(I) = COSOFA(IHEM)*SINLAT(I) - SINOFA(IHEM)*COSLAT(I)*
     1    COSLON(I)
        COLAT(I) = ACOS(COLAT(I)) * SQRT(RATIO(I))
        ALON(I) = AMOD(ATAN2(+SINLON(I)*COSLAT(I),SINLAT(I)*
     1    SINOFA(IHEM)+COSOFA(IHEM)*COSLAT(I)*COSLON(I)) -
     2    ASLONA(IHEM)+3.*PI,PI2) - PI
    8 CONTINUE
      RETURN
      END
C