Error in MODIS atmospheric correction

[yunxiao]

Dear David and all,

 

I encountered a problem to correct InSAR atmospheric delay by MODIS data. I manually downloaded the MOD05_L2.A2007059.mosaic.061.2019211133235.psrpcs_000501361656.Water_Vapor_Infrared.hdf and MOD05_L2.A2007059.mosaic.061.2019211133235.psrpcs_000501361656.Water_Vapor_Near_Infrared.hdf from https://ladsweb.modaps.eosdis.nasa.gov/search/, and convert the hdf format of MODIS data into grd format on the https://mygeodata.cloud/converter/hdf5-to-grd website. Rename the converted MODIS data in grd format to MODIS_Water_Vapor_Infrared_20070228.grd and MODIS_Water_Vapor_Near_Infrared_20070228.grd. However, running the aps_modis(2,2), I faced the following error:

 

aps_modis(2,2)

 

Step 2: Compute MODIS tropospheric delay for individual dates

   PARM: modis_datapath='/media/tyx/tyx/ASAR-HK-MT/APS/MODIS/MODIS_PS/MODIS'

   PARM: spectrometer_PIconversion=6.26264 6.351 6.16907 6.10976 6.10073 6.12183 6.21392 6.39036 6.21237 6.11277 6.11729 6.15835 6.11581 6.1614 6.33642 6.14917 6.10073 6.14765 6.24684 6.41349 6.21083

   PARM: region_res=0.008333

   PARM: region_lon_range=113.5 114.6

   PARM: region_lat_range=21.9 22.8

   PARM: modis_recalibrated='n'

   PARM: stamps_processed='y'

   PARM: modis_calibration=0.95

Lon range: 113.5 -- 114.6 degrees

Lat range: 21.9 -- 22.8 degrees

Output resolution is assumed to be 0.008333 degrees

Stamps processed structure

Conversion factor varies for each SAR date.

Starting the computation for each SAR date

Error using netcdflib

The NetCDF library encountered an error during execution of 'open' function - 'Unknown file

format (NC_ENOTNC)'.

 

Error in netcdf.open (line 59)

        [varargout{:}] = netcdflib ( 'open', filename, varargin{1} );

 

Error in grdread2 (line 61)

ncid = netcdf.open(file, 'NC_NOWRITE');

 

Error in aps_modis_SAR (line 148)

    [lon_grid,lat_grid,watervap] = grdread2(file);

 

Error in aps_modis (line 112)

aps_modis_SAR('modis_batch_file.txt')

 

Please help me check if the organization structure and the rename way of the MODIS file are correct. Or where is the problem? This problem has been bothering me for a long time, please help me solve this problem.

 

 

Thanks for any hint in advance.

Cheers,

yunxiao

[Fielding, Eric J (US 329A)]

Dear Yunxiao,

 

It looks like that “grd” format converter that you found is not the same as the GMT NetCDF .grd format. That is why it is not reading correctly.

 

I would suggest using “gdal_translate” from a GDAL package with output format “GMT”.

 

++Eric

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[REYHAN AZERIANSYAH]

Dear Yunxiao,

Your PIconversion must only one value. There is fixed coefficients for that and not what you have shown.

Thank you
Cheers,
Reyhan

[yunxiao]

Dear ++Eric,

 

Thank you very much for your help. I tried to convert hdf into grd using the “gdal_translate” from a GDAL package, but there were several problems.

‘Gdalwarp -overwright Water_Vapor_Near_Infrared_name_band.hdf  -of netCDF MODIS_yyyymmdd.nc’ and ‘gdal_translate MODIS_yyyymmdd.nc -of  GMT MODIS_yyyymmdd.grd’, but I can't find -overwrigth on gdal.

Can you give me a detailed description of how to convert hdf into grd using Gdalwarp and gdal_translate?

 

Thank you
Cheers,

yunxiao

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