program read_ssmi
c
c   This sample program provides code statements to read SSMI data.
c
c   The SSMI data are on a 1080 X 540 element grid with the origin at
c   89.833 degrees North latitude and 0.167 degrees East longitude
c   (i.e., a 1/3 degree by 1/3 degree resolution grid ranging from
c   89.833 degrees North to 89.833 degrees South in latitude and 
c   0.167 degrees East to 359.833 degrees East in longitude).  There are 
c   12 monthly data files for 1994.
c
c   Parameter Declarations:
c

      integer*2 spd(1080,540)   ! SSMI data in cm/sec.
                                ! 9999 indicates no data

      byte num(1080,540) 	! num of SSMI data counts to compute avg
      integer*2 inum(1080,540) 	! num of SSMI data counts to compute avg

      real*4 xmin,xmax          ! minimum and maximum speeds in data in m/sec

C  Open & read a data file.

      open(8,file='spd9401.dat',form='unformatted')
      read(8) xmin,xmax
      read(8) spd
      read(8) num
      close(8)

C   Print xmin and xmax to console window:

      write(*,*) ' xmin, xmax ',xmin,xmax

c  Convert the SSMI speed to meters per second & print the values:

      do 100 i = 1, 5
         if ( spd(i,270).ne.9999 ) then
            write(*,*) '  spd(',i,', 270  ) = ',spd(i,270)/100.0
         endif
 100  continue
	
c  Print sample count num (as byte values) :

      do 200 i = 1, 5
         if ( num(i,270).ne.9999 ) then
            write(*,*) '  num(',i,', 270  ) = ',num(i,270) ! counts.
         endif
 200  continue

c
c Sample Output from file: spd9401.dat 
c 
c xmin, xmax     1.04000    19.04000
c 
c  spd(  1, 270  ) =   5.22000
c  spd(  2, 270  ) =   5.35000
c  spd(  3, 270  ) =   5.25000
c  spd(  4, 270  ) =   5.08000
c  spd(  5, 270  ) =   5.43000
c 
c  num(  1, 270  ) =   50
c  num(  2, 270  ) =   55
c  num(  3, 270  ) =   54
c  num(  4, 270  ) =   50
c  num(  5, 270  ) =   59
c 
c
c  Note that array NUM is a byte array.  If you wish to utilize NUM values
c  in your computations, declare a new integer*2 array, INUM (as above),
c  and read in the byte array NUM into the new integer array INUM
c  as follows:

      do 400 j = 1, 540
         do 300 i = 1, 1080
            if ( inum(i,j) .GE. 0 ) then
               inum(i,j) = num(i,j)
            else
               inum(i,j) = 9999 ! only to guard against
                                ! spurious neg. values,
                                ! if any.
            endif
 300     continue
 400  continue

c  Print inum(i,j) [integer*2] as printed for num(i,j) [byte]:

      do 500 i = 1, 5
         write(*,*) ' inum(',i,', 270  ) = ',inum(i,270) ! counts.
 500  continue

c
c Sample inum OUTPUT 
c 
c inum(  1, 270  ) =   50
c inum(  2, 270  ) =   55
c inum(  3, 270  ) =   54
c inum(  4, 270  ) =   50
c inum(  5, 270  ) =   59
c 

      stop
      end