Re: Open MYD09GQ.A2006060.h25v06.005.2008075213332.hdf using a NCL script

Filippo,
You have commented out the part from the template code about reading the file with the .he2 extension. You need to do this to read the hdfeos coordinate variables. They do not
show up when you read the file as a straight hdf file. We hope to improve the code so that this is done internally but for now you need to read the file once as hdf and then again
as hdfeos in order to get the complete file contents.
 -dave

On Dec 11, 2012, at 9:05 AM, Filippo Locci wrote:

> Hi,
> using examples from http://www.hdfeos.org/zoo/index_openLPDAAC_Examples.php
> and modifing a script to open a MYD09GQ file but an error occurs:
> fatal:["Execute.c":5773]:variable (YDim) is not in file (eos_file)
>
> My script:
>
> ;This example code illustrates how to access and visualize LP_DAAC_MYD Grid file in 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_at_hdfgroup.org or post it at the HDF-EOS Forum (http://hdfeos.org/forums).
>
> load "$NCARG_ROOT/lib/ncarg/nclex/gsun/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
>
> ; This is an example of a 2-D grid file data field.
> ; It is assumed users know how to obtain information such as _FillValue from HDFView.
> ; For information about HDFView, visit http://www.hdfgroup.org/hdf-java-html/hdfview/.
>
> begin
>
> eos_file=addfile("MYD09GQ.A2006060.h25v06.005.2008075213332.hdf", "r") ; Read file.
> ; he2_file = addfile("MYD09A1.A2007273.h03v07.005.2007285103507.hdf.he2", "r") ; Read file for the second time to efficiently obtain lat and lon.
>
> ; List available fields and attributes.
> print(eos_file)
>
> ; read data field
> data_raw = eos_file->sur_refl_b01_1
>
> ; print(data_raw)
>
> ; Apply scale factor according to the field attribute
> ; correct_data_value = (raw_data_value - offset) * scale_factor
> data = (data_raw - data_raw@add_offset) * data_raw@scale_factor
>
> data@_FillValue = (data_raw@_FillValue - data_raw@add_offset) * data_raw@scale_factor
>
> data@long_name = data_raw@long_name
> data@units = data_raw@units
>
> ; Associate longitude and latitude
> ; data@lat2d=he2_file->GridLat_MOD_Grid_500m_Surface_Reflectance
> ; data@lon2d=he2_file->GridLon_MOD_Grid_500m_Surface_Reflectance
>
>
> lat=eos_file->YDim ; associate longitude and latitude
> lon=eos_file->XDim ;
> lat@_FillValue=-999.0
> lon@_FillValue=-999.0
>
>
> data@lat2d=lat
> data@lon2d=lon
>
>
> xwks=gsn_open_wks("pdf","MYD09GQ.A2006060.h25v06.005.2008075213332.hdf_sur_refl.ncl") ; open workstation
>
> res=True ; plot mods desired
> res@cnFillOn=True ; enable contour fill
> res@gsnMaximize=True; make plot large
> res@gsnPaperOrientation = "portrait" ; force portrait orientation
> res@cnLinesOn=False ; turn off contour lines
> res@cnLineLabelsOn = False; turn off contour line labels
> res@gsnSpreadColors = True ; use the entire color spectrum
> res@cnFillMode = "RasterFill" ; faster
> res@lbOrientation ="vertical" ;vertical labels
> res@cnMissingValFillPattern = 0 ; missing value pattern is set to "SolidFill"
> res@cnMissingValFillColor = 0; white color for missing values
>
> ; the following 5 sentences are used to create a zoomed image
> res@mpLimitMode = "LatLon"
> res@mpMinLatF = min(data@lat2d) ; Set limits of map, based on the min/max of the dataset latitude/longitude
> res@mpMaxLatF = max(data@lat2d) ;
> res@mpMinLonF = min(data@lon2d) ;
> res@mpMaxLonF = max(data@lon2d) ;
>
> gsn_define_colormap(xwks,"BlAqGrYeOrReVi200") ; choose colormap
> res@tiMainString = "MYD09GQ.A2006060.h25v06.005.2008075213332.hdf" ; create title
> res@gsnLeftString = "Field name: " + data@long_name
> res@gsnRightString = "Units: " + data@units
>
> plot=gsn_csm_contour_map_ce(xwks,data,res) ; create plot
>
> ; cleaning up used resources
> delete(plot)
> delete(res)
> delete(xwks)
> delete(data)
> delete(data_raw)
> delete(eos_file)
> ; delete(he2_file)
>
> end
>
> I haven't a file where I could read the geolocation. It's possible to read this file via HDF viewer but
> I'm not able to open this file via an NCL script.
> Please, give me a suggestion.
> Thank you
> F
> --
> Filippo Locci
> PhD Student
> International PhD in
> Environmental Science and Engineering
> University of Cagliari
> Tel. +390706757701
> Mob. +393471372292
>
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Received on Wed Dec 12 03:19:08 2012