; Copyright (C) 2019 The HDF Group
;   All rights reserved.
;
;  This example code illustrates how to access and visualize
; LP DAAC MCD19A2 HDF-EOS2 Sinusoidal Grid file using NCL.
;
;  If you have any questions, suggestions, comments on this example,
; please use the HDF-EOS Forum (http://hdfeos.org/forums).
;
;  If you would like to see an  example of any other NASA HDF/HDF-EOS data
; product that is not listed in the HDF-EOS Comprehensive Examples page
; (http://hdfeos.org/zoo), feel free to contact us at eoshelp@hdfgroup.org
; or post it at the HDF-EOS Forum (http://hdfeos.org/forums).
;
;
; Usage:save this script and run
;
; $ncl MCD19A2.A2010010.h25v06.006.2018047103710.hdf.ncl
;

; Tested under: NCL 6.6.2
; Last Updated: 2019-05-23
begin

; creating a new array to place numerous days/months/years together
 twoday_data = new((/1753,1200,1200/),"double")

; listing of all HDF files in a directory
;  ls *.hdf > MODISLIST.txt

  ifiles = "MCD19A2.A2002152.h12v04.006.2018017002927.pscs_000501348964.hdf"
;  file_name = systemfunc ("ls MCD19A2.A2019120.h12v04.006.2019122083552.hdf") ; file paths
;   ifiles = systemfunc ("ls MCD19A2.A2002*.hdf") ; file paths

   ifile = addfile(ifiles(t), "r")
;   print(ifile)

; Read file as HDF-EOS2 file to obtain lat and lon.
;  he2_file = addfile(file_name + ".he2", "r")
  he2_file = addfile(ifiles(t) + ".he2", "r")

; Read a specific variable.
  data_raw = he2_file->Optical_Depth_047_grid1km

; Copy attributes.
  data@long_name = data_raw@long_name
  data@units = data_raw@unit

; Associate longitude and latitude.
  data@lat2d = he2_file->GridLat_grid1km
  data@lon2d = he2_file->GridLon_grid1km

; create AOD extraction file for a given location
  data_raw1 =  data_raw(0,{40.821},{-73.949})
 asciiwrite("test.txt",data_raw1)