ReadATI Subroutine

  SUBROUTINE ReadATI( FileRoot, TopATI, DepthT, PRTFile )
  !! Reads in the top altimetry

    INTEGER,            INTENT( IN ) :: PRTFile
    CHARACTER (LEN= 1), INTENT( IN ) :: TopATI
    REAL      (KIND=8), INTENT( IN ) :: DepthT
    ! REAL      (KIND=8), ALLOCATABLE  :: phi( : ) ! LP: Removed as seems to have been moved to ComputeBdryTangentNormal
    CHARACTER (LEN=80), INTENT( IN ) :: FileRoot

    SELECT CASE ( TopATI )
    CASE ( '~', '*' )
       WRITE( PRTFile, * ) '__________________________________________________________________________'
       WRITE( PRTFile, * )
       WRITE( PRTFile, * ) 'Using top-altimetry file'

       OPEN( UNIT = ATIFile,   FILE = TRIM( FileRoot ) // '.ati', STATUS = 'OLD', IOSTAT = IOStat, ACTION = 'READ' )
       IF ( IOsTAT /= 0 ) THEN
          WRITE( PRTFile, * ) 'ATIFile = ', TRIM( FileRoot ) // '.ati'
          CALL ERROUT( 'ReadATI', 'Unable to open altimetry file' )
       END IF

       READ(  ATIFile, * ) atiType
       AltiType: SELECT CASE ( atiType( 1 : 1 ) )
       CASE ( 'C' )
          WRITE( PRTFile, * ) 'Curvilinear Interpolation'
       CASE ( 'L' )
          WRITE( PRTFile, * ) 'Piecewise linear interpolation'
       CASE DEFAULT
          CALL ERROUT( 'ReadATI', 'Unknown option for selecting altimetry interpolation' )
       END SELECT AltiType

       READ(  ATIFile, * ) NatiPts
       WRITE( PRTFile, * ) 'Number of altimetry points = ', NatiPts
       NatiPts = NatiPts + 2   ! we'll be extending the altimetry to infinity to the left and right

       ALLOCATE( Top( NatiPts ), Stat = IAllocStat )
       ! ALLOCATE( phi( NatiPts ), Stat = IAllocStat ) ! LP: Removed as seems to have been moved to ComputeBdryTangentNormal
       IF ( IAllocStat /= 0 ) &
            CALL ERROUT( 'BELLHOP:ReadATI', 'Insufficient memory for altimetry data: reduce # ati points' )

       WRITE( PRTFile, * )
       WRITE( PRTFile, * ) ' Range (km)  Depth (m)'

       atiPt: DO ii = 2, NatiPts - 1

          SELECT CASE ( atiType( 2 : 2 ) )
          CASE ( 'S', '' )
             READ(  ATIFile, * ) Top( ii )%x
             ! LP: This condition was previously ii == NatiPts,
             ! which will never be satisfied due to the loop bounds
             IF ( ii < Number_to_Echo .OR. ii == NatiPts - 1 ) THEN   ! echo some values
                WRITE( PRTFile, FMT = "(2G11.3)" ) Top( ii )%x
             END IF
          CASE ( 'L' )
             READ(  ATIFile, * )                   Top( ii )%x, Top( ii )%HS%alphaR, Top( ii )%HS%betaR, Top( ii )%HS%rho, &
                                                                Top( ii )%HS%alphaI, Top( ii )%HS%betaI
             ! LP: Same change as above
             IF ( ii < Number_to_Echo .OR. ii == NatiPts - 1 ) THEN   ! echo some values
                WRITE( PRTFile, FMT = "(7G11.3)" ) Top( ii )%x, Top( ii )%HS%alphaR, Top( ii )%HS%betaR, Top( ii )%HS%rho, &
                                                                Top( ii )%HS%alphaI, Top( ii )%HS%betaI
             END IF
          CASE DEFAULT
             CALL ERROUT( 'ReadATI', 'Unknown option for selecting altimetry option' )
          END SELECT

          IF ( Top( ii )%x( 2 ) < DepthT ) THEN
             CALL ERROUT( 'BELLHOP:ReadATI', 'Altimetry rises above highest point in the sound speed profile' )
          END IF
       END DO atiPt

       CLOSE( ATIFile )

       Top( : )%x( 1 ) = 1000.0 * Top( : )%x( 1 )   ! Convert ranges in km to m

    CASE DEFAULT   ! no altimetry given, use SSP depth for flat top
       ALLOCATE( Top( 2 ), Stat = IAllocStat )
       IF ( IAllocStat /= 0 ) CALL ERROUT( 'BELLHOP', 'Insufficient memory for altimetry data'  )
       Top( 1 )%x = [ -sqrt( huge( Top( 1 )%x( 1 ) ) ) / 1.0d5, DepthT ]
       Top( 2 )%x = [  sqrt( huge( Top( 1 )%x( 1 ) ) ) / 1.0d5, DepthT ]
    END SELECT

    CALL ComputeBdryTangentNormal( Top, 'Top' )

    IF ( .NOT. monotonic( Top%x( 1 ), NAtiPts ) ) THEN
       CALL ERROUT( 'BELLHOP:ReadATI', 'Altimetry ranges are not monotonically increasing' )
    END IF

  END SUBROUTINE ReadATI