; $Header$

Function get_sd, filename, name

;Attempt to catch some errors
CATCH, Error_status
If Error_status NE 0 then begin
       Print, 'Error index: ', Error_status
       Print, 'Error message: ', !ERR_STRING
       var = -99999.
       return, var
endif

  sd_id = hdf_sd_start(filename,/read)
  index = hdf_sd_nametoindex(sd_id, name)
  sds_id = hdf_sd_select(sd_id,index)
  hdf_sd_getdata, sds_id, var
  hdf_sd_endaccess, sds_id
  hdf_sd_end, sd_id
return, var
end

;############# Choose time ##############
yr='2008'
mm='04'
dd='14'
nlev=72

dir_in = 'YOUR DATA DIRECTORY'
; The GEOS-5 data can be downloaded from GSFC NCCS MSS dirac at the directory
; /archive/dao_ops/dao_ops/ARCTAS_REPLAY/GEOSdas-2_1_2/d5_arctas_02/chem/Y2008/
; /archive/dao_ops/ARCTAS_REPLAY/GEOSdas-2_1_2/d5_arctas_02/chem/Y2008/
;
sciafile = dir_in+'d5_arctas_02.tavg2d_aer_x.'+yr+mm+dd+'_1630z.hdf'
;
   ;Does the filename exist?
    ;if(file_search(sciafile) eq '') then begin
    ; print, sciafile+': not found, continuing'
    ; continue
    ;endif
    print,sciafile

   ;Open HDF file
   file_id = hdf_open(sciafile, /read)

   lat = get_sd(sciafile, 'lat')
   lon = get_sd(sciafile,  'lon')
   nt = get_sd(sciafile,  'time')
   duaot = get_sd(sciafile, 'DUEXTTAU')

   hdf_close, file_id
;print,'size of duaot=',SIZE(duaot,/dimensions)

end