Documentation for GPCP Satellite-Derived (IR) GPI Daily Rainfall
     Estimates:

     to get the file via anonymous ftp, do the following:
        1.  ftp ftp.ncep.noaa.gov
        2.  login with userid anonymous  (use your e-mail ID as the password)
        3.  cd pub/precip/gpi/daily
        4.  set ftp to binary mode (bin)
        5.  get data daily_gpi_yyyy ( year of the data)

     Each file contains daily data for the certain year for 1x1 degree
     resolushion grid. The data are stored in 360 x 80 arrays and each
     value represents the estimated areal average data for 1x1 degree
     "box". Missing values are identified as "-9999". The array 
     orientation is:


  40N  ----------------------------      -----------------
       |       |       |       |         |       |       |
       | (1,1) | (2,1) | (3,1) |   . . . |(359,1)| (360,1)
       |       |       |       |         |       |       |
  39N  ----------------------------      -----------------
       |       |       |       |         |       |       |
       | (1,2) | (2,2) | (3,2) |   . . . |(359,2)| (360,2)
       |       |       |       |         |       |       |
                                     .
                                     .
                                     .
  39S  ----------------------------      -----------------
       |       |       |       |         |       |       |
       | (1,80)| (2,80)| (3,80)|   . . . |(359,80) (360,80)
       |       |       |       |         |       |       |
  40S   ----------------------------      -----------------
       |       |       |       |         |       |       |
       0      1E      2E      3E        2W      1W       0
 
      Units for rainfall estimates are mm/day.
      The data are available from October 1996.

      The data can be read in FORTRAN as follows:

      real*4  dgpi(360,80)

      open(300, file = ofile, form='unformatted', status='old',
     1     access='direct',recl=360*80*4)

      do 200 rrec = 1, 365 
c     or 366 for the leap year
      read(300, rec = rrec) ((dgpi(i,j),i=1,360),j=1,80)
 200  continue

     We update these data approximately once a month.