program soilpop
implicit none

!====================================================================
! SOILPOP30 is a global database of soil population fractions (%) 
! It is derived from STATSGO soil texture data, following 
! Tegen et al (2002) and Shirazi et. al (1988).
! The database is available for download: wwww.seevccc.rs/GMINER30

! Data are on 30-seconds gird (~ km) and are organized in 27 tiles 
! with NXT x NYT points each.
! There is 4 soil population categories:
!      CLY    clay 
!      SLT    silt
!      SNF    fine sand
!      SNC    coarse sand
!
! This program is intended for reading soil population fractions (%) 
! from the database and writing ASCII files (lon, lat, mineral frac). 
!====================================================================

integer :: i, j, it, k, jj 
real, parameter :: dlo=1./120.,dla=1./120.
integer, parameter :: nxt=40./dlo+1, nyt=50./dla+1
integer, parameter :: nmin=12, ntile=27
real, dimension (nxt,nyt) :: sc
real, dimension (ntile) :: tlon, tlat
character*7, dimension (ntile) :: ctile
character*4, dimension (4) :: cpop
integer*2 kcly(nxt,nyt)
data  cpop /'CLY', 'SLT', 'SNF', 'SNC'/

data ctile /                                                       &
            'W180N90', 'W140N90', 'W100N90', 'W060N90', 'W020N90', &
            'E020N90', 'E060N90', 'E100N90', 'E140N90',            &    
            'W180N40', 'W140N40', 'W100N40', 'W060N40', 'W020N40', &
            'E020N40', 'E060N40', 'E100N40', 'E140N40',            &
            'W180S10', 'W140S10', 'W100S10', 'W060S10', 'W020S10', &
            'E020S10', 'E060S10', 'E100S10', 'E140S10'/ 

print*, 'Dimensions of each tile:', nxt,'x', nyt
print*, 'dlon:', dlo,'    dlat:', dla

do k=1,4
  print*, 'Processing soil population:    ', cpop(k)

  do it=1,ntile
  print*, 'Processing tile:',it

  OPEN(30,FILE=ctile(it)//'.'//cpop(k)  &
         ,FORM='UNFORMATTED',STATUS='UNKNOWN',ACCESS='DIRECT',RECL=NXT*NYT*4)
      READ(30,REC=1) ((sc(i,j),i=1,NXT), j=1,NYT)
   CLOSE(30)
   enddo

enddo

endprogram soilpop