Re: conversion of of data: hdf to netcdf

> I am new user of ncl.
> I recently discover the function ncl_convert2nc
> (http://www.ncl.ucar.edu/Document/Tools/ncl_convert2nc.shtml).
> I wanted to help someone who are using GRADS only.
>
> When I am trying to convert hdf data at this link
> ftp://disc2.nascom.nasa.gov/data/s4pa/TRMM_L3/TRMM_3B42/2004/001/3B42.040102.0.6.HDF.Z
>
> The error message appearing is the following:
>
> ncl_convert2nc: file '3B42.020801.0.6.nc' not readable,
> does not contain recognized data, or doesn't exist, skipping.
>
> Processing file: 3B42.020801.0.6.HDF...
> Copyright (C) 1995-2006 - All Rights Reserved
> University Corporation for Atmospheric Research
> NCAR Command Language Version 4.2.0.a034
> The use of this software is governed by a License Agreement.
> See http://www.ncl.ucar.edu/ for more details.
>
>
> How can I do to resolve this problem?
>
> ---------------------------------

Bonjour,

[1] 3B42.040102.0.6.HDF.Z
    The Z extension is the problem.

    gunzip 3B42.040102.0.6.HDF.Z

[2] ncl_filedump 3B42.040102.0.6.HDF

    to look at the hdf file directly.

    This also works for nc, grib and hdf-eos.

[3] ncl_convert2nc 3B42.040102.0.6.HDF

    to convert to netCDF

    This also works for nc, grib and hdf-eos.

[4] ncl_filedump 3B42.040102.0.6.nc
    or
    ncdump -h ncl_filedump 3B42.040102.0.6.nc

    to look at the netCDF file

[5] I am not knowledgable about GrADS. However,
    I think that it only understands COARDS conforming
    netCDF/HDF. The original hdf file is not COARDS
    conforming. Hence, the converted netCDF is not
    COARDS conforming.

[6] GrADS info

    http://grads.iges.org/grads/gadoc/SDFdescriptorfile.html

    Also, a person here at NCAR has created the following
    to help people read non-COARDS conformin netCDF.

    http://www.cgd.ucar.edu/cas/asphilli/ddfhelp.html

[7] I have placed an NCL script that reads the HDF and
    creates a CF/COARDS conforming netCDF at:

    http://www.cgd.ucar.edu/web/public_html/shea/TRMM.3B42.hdf2nc.ncl

    Just change the "diri" variable, if necessary.

    When run on the above file it creates:

    http://www.cgd.ucar.edu/web/public_html/shea/3B42.2004010200.nc

Bon chance

     
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Received on Sat Mar 03 2007 - 09:01:40 MST