program read_airs
!                .      .    .                                       .
! subprogram:    read_airs                  read bufr format airs data

  use kinds, only: r_kind,r_double,i_kind

! Number of channels for sensors in BUFR
  integer(i_kind),parameter :: n_airschan = 281                           !--- 281 subset ch out of 2378 ch for AIRS
  integer(i_kind),parameter :: n_amsuchan =  15
  integer(i_kind),parameter :: n_hsbchan  =   4
  integer(i_kind),parameter :: n_totchan  = n_amsuchan+n_airschan+n_hsbchan+1

! BUFR file sequencial number
  character(len=512)  :: table_file
  integer(i_kind)     :: lnbufr = 10
  integer(i_kind)     :: lnbufrtab = 11
  integer(i_kind)     :: irec,isub,next

! Variables for BUFR IO    
  real(r_double),dimension(2) :: aquaspot
  real(r_double),dimension(12,3) :: allspot
  real(r_double),dimension(n_totchan) :: allchan
  
  character(len=8)  :: subset
  character(len=80) :: allspotlist
  integer(i_kind)   :: iret, ireadmg,ireadsb

  logical           :: airstab
  character(len=80) :: infile

  infile='airsbufr'

  allspotlist='SIID YEAR MNTH DAYS HOUR MINU SECO CLATH CLONH SAZA BEARAZ FOVN'

! Open BUFR file
  open(lnbufr,file=infile,form='unformatted')

! Open BUFR table
  table_file = 'airs_bufr.table'      ! make table file name
  inquire(file=table_file,exist=airstab)
  if (airstab) then
     open(lnbufrtab,file=trim(table_file))
     call openbf(lnbufr,'IN',lnbufrtab)
  else
     call openbf(lnbufr,'IN',lnbufr)
  endif
  call datelen(10)

! Big loop to read data file
  next=0
  do while(ireadmg(lnbufr,subset,idate)>=0)
     next=next+1
     read_loop: do while (ireadsb(lnbufr)==0)

!       Read AIRSSPOT , AMSUSPOT and HSBSPOT

        call ufbrep(lnbufr,allspot,12,3,iret,allspotlist)

        if(iret /= 3) cycle read_loop

!       Check that number of airs channel equals n_airschan
!       only done until they match for one record and ndata is updated

!        Read AIRSCHAN or AMSUCHAN or HSBCHAN

         call ufbrep(lnbufr,allchan,1,n_totchan,iret,'TMBR')

         if( iret /= n_totchan)then
            write(6,*)'READ_AIRS:  ### ERROR IN READING ', ' BUFR DATA:', &
                 iret, ' CH DATA IS READ INSTEAD OF ',n_totchan
            cycle read_loop
         endif

!        Read AQUASPOT
         call ufbint(lnbufr,aquaspot,2,1,iret,'SOZA SOLAZI')

     enddo read_loop
  enddo

  call closbf(lnbufr)  ! Close bufr file

end program read_airs