On Jan 5, 2013, at 2:34 PM, Taylor Binnington <tbinnington@xxxxxxxxx> wrote:
> Thank you all for your help!
>
> Christopher: I am aware of the OPeNDAP servers, and you're right, that's
> actually the direction I'm trying to head in. In fact, I've been in contact
> with Dana about data access options before, since I'm looking to subset the
> data in a different way than the online tool allows.
>
> I would very much have liked to stick with this option, but I have found that
> the HDF files available on the OPeNDAP servers (and even the *.nc files that
> can be downloaded by specifying the NetCDF option for the online subsetting
> tool that you mentioned) can not be opened by the NetCDF c++ libraries.
If any of this process should be bombproof, opening converted .nc files should
be it. Suggest you try both
(1) a file from the FTP Subsetter, converted to netCDF, and
(2) a MERRA file downloaded from OPeNDAP as netCDF. To do this, take the
OPeNDAP URL for the data file (ending in .hdf) and append .nc, e.g.,
http://goldsmr3.sci.gsfc.nasa.gov/opendap/MERRA/MAI3CPASM.5.2.0/1979/01/MERRA100.prod.assim.inst3_3d_asm_Cp.19790101.hdf.nc
(This will take a little while to download, it's very big.)
These netCDF files are created through completely different codes, no
relationship at all to each other. If you cannot open either of these, then
the problem is likely in either your library installation, in which case, I
suggest reinstalling (might as well use the latest), or in your code. Note
that it's possible for memory errors (uninitialized pointers, double free's,
etc.) from one part of a code to show up later and in other parts of the code.
> Actually this was the problem that I first encountered, prompting me to start
> this thread (you can see the error that I received at the top of this
> thread), and I thought that I was told that I would not actually be able to
> open these files using only NetCDF4. It also appears that the augmentation
> tool, recommended earlier, will not work since it is designed only to augment
> HDFEOS5 files (not HDFEOS4, which is what MERRA is, except for the small java
> exception that you spoke of Chris).
>
> So is it unexpected that I am not able to open MERRA HDF files, obtained
> through the official OPeNDAP URLs, using the stock NetCDF4 C++ legacy
> libraries? This sort of brings me back to my first post. Thank you in
> advance!!
>
> Taylor
--
Dr. Christopher Lynnes, NASA/GSFC, ph: 301-614-5185
