PROGRAM READFPP
!
! Reads in pp files 
!
  IMPLICIT NONE  
!
! Variables
!
  INTEGER, PARAMETER                   :: N_TOTAL_MONTHS = 1536 
      ! Number of ppfields, equal to number of months
  INTEGER                              :: I, J      
      ! Loop variables
  INTEGER,              DIMENSION(45)  :: IHEAD  
      ! Integer header
  REAL,                 DIMENSION(19)  :: RHEAD  
      ! Real header
  REAL,    ALLOCATABLE, DIMENSION(:)   :: ALONG 
      ! Array of longitudes
  REAL,    ALLOCATABLE, DIMENSION(:)   :: ALAT 
      ! Array of latitudes
  REAL,    ALLOCATABLE, DIMENSION(:,:) :: DATA   
      ! Data array
!
! Open file
!
  OPEN(    UNIT = 10,                  &
         ACTION = "READ",              &
           FILE = "/clim_var/hc2100/OBS/marine/HadISST/karl/"// & 
                  "hadisstbc_sic_72x36_1871_1998.pp",           &
           FORM = "UNFORMATTED",       & 
         STATUS = "OLD")
!
! Loop over the total number of months in the file
!
  DO I = 1, N_TOTAL_MONTHS
!
! Read the mixed integer/real header
!
    READ(UNIT = 10) IHEAD, RHEAD
!
! Allocate space for the longitude, latitude and data arrays using 
! the number of longitudes (ihead(19)) and the number of latitudes 
! (ihead(18)).
!
    IF (.NOT. ALLOCATED (ALONG)) THEN
       ALLOCATE (ALONG(IHEAD(19)))
    ELSE
       DEALLOCATE (ALONG)
       ALLOCATE (ALONG(IHEAD(19)))
    END IF  
!
    IF (.NOT. ALLOCATED (ALAT)) THEN
       ALLOCATE (ALAT(IHEAD(18)))
    ELSE
       DEALLOCATE (ALAT)
       ALLOCATE (ALAT(IHEAD(18)))
    END IF  
!
    IF (.NOT. ALLOCATED (DATA)) THEN
       ALLOCATE (DATA(IHEAD(19), IHEAD(18)))
    ELSE
       DEALLOCATE (DATA)
       ALLOCATE (DATA(IHEAD(19), IHEAD(18)))
    END IF  
!
! Compute the longitude and latitude arrays from header data
!
    DO J = 1, IHEAD(19)
      ALONG(J) = RHEAD(16) + FLOAT(J)*RHEAD(17)
    ENDDO
!
    DO J = 1, IHEAD(18)
      ALAT(J) = RHEAD(14) + FLOAT(J)*RHEAD(15)
    ENDDO
!
! Read data array
!
    READ(UNIT = 10) DATA  
!
! Quick check to see what we have got
!
    WRITE(6,*) IHEAD(1), IHEAD(2), ALONG(1), ALAT(1), DATA(1, 1)
  END DO
!
  CLOSE(10)
!
END