c
c NAME: read_hirs_as.f
c
c PURPOSE:  Example program for reading HIRS all-sky data.
c
c COMPILATION SEQUENCE:
c                       f77 read_hirs_as.f
c
c NOTES:
c         HIRS all-sky swath data record (54 bytes data record length)
c           xtime = time in seconds from start of day
c           xlon  = longitude in degrees starting from GM (0-360)
c           xlat  = latitude in degrees (-90 to 90)
c           iline = line number for individual orbit.  Note that one
c                   AS daily file contains about 14 orbits.
c           isp   = scan position (1-56)
c           xszen = solar zenith angle in degrees (90 = night)
c           xalt  = satellite altitude in km
c           tb(19)= 19 channels of HIRS brightness temperature in Kelvin           
c           iref  = HIRS channel 20 visible reflectance (0 to 100)
c                   with 100 being most reflective
c      
c           tb missing data fields are filled with -99 values (before scaling)
c
c CREATION HISTORY:  Darren Jackson ESRL/CIRES  July 2006
c

      PROGRAM read_hirs_as
c
      INTEGER satid,year4,jday,i,k

c  variables used for reading data

      INTEGER   itime
      INTEGER*2 ilon,ilat,iline,iszen,ialt,itb(19)
      BYTE      isp,iref

c  variables after offsets and scaling

      REAL      xtime,xlon,xlat,xszen,xalt,tb(19)

c
c Open input file
c

      OPEN(10,file='HIRS.N12.Y91.D180.AS',access='direct',recl=54)

c
c Read data, write ouput data
c

      DO i=1,1000000
         READ(10,rec=i,err=99) itime,ilon,ilat,iline,isp,iszen,ialt,
     &        iref,itb
         xtime=itime/100.
         xlon=(ilon/100.)+180.
         xlat=ilat/100.
         xszen=iszen/100.
         xalt=ialt/10.
         DO k=0,18
            tb(k)=(itb(k)/100.)+100.
         ENDDO

         WRITE(*,*) xtime,xlon,xlat,xszen,xalt,iline,isp
         DO n=0,18 
            WRITE(*,*) 'channel=',n+1,tb(n)
         ENDDO
         WRITE(*,*) 'channel=  20',iref
         WRITE(*,*) ' '
      ENDDO
      CLOSE(10)

 99   CONTINUE
      END