Re: [netcdf-java] Can't seem to be able to create a NetCDF file with NetCDF-Java that conforms to the CF-1.6/H5.3 format

  • To: Aleksander Vines <aleksander.vines@xxxxxxxx>
  • Subject: Re: [netcdf-java] Can't seem to be able to create a NetCDF file with NetCDF-Java that conforms to the CF-1.6/H5.3 format
  • From: Roland Schweitzer - NOAA Affiliate <roland.schweitzer@xxxxxxxx>
  • Date: Fri, 24 Jan 2014 16:46:47 -0600
What netCDF version do you use in you FileWriter.createNew?

I'm able to make CF files for point features readable by toolsUI, but I
restrict myself to NetcdfFileWriter.Version.netcdf3?


On Fri, Jan 24, 2014 at 7:55 AM, Aleksander Vines <aleksander.vines@xxxxxxxx
> wrote:

> Hi,
> I need some help with the creation of a NetCDF file.
> I'm attempting to create the NetCDF file programmatically. I have a lot of
> point data, and I want to be able to create different types of NetCDF-files
> after extracting different subsets of these points. I want the files to
> conform to CF-1.6 (as far as its possible with the input I got).
> I'm using NetCDF-java 4.3.
> I've found a "Short guide to writing files using CF-1.6 Discrete Sampling
> Features Conventions":
>    -
> From this guide, I concluded that I should support the format specified in
> CF-1.6 H5.3 (see below) in my application (I'm also writing other kind of
> formats)
>    -
>    -  I've figured one obvious error in this example, and that is that
>    they referred to name_strlen as a dimension without specifying it in the
>    dimension list.
> ncdump of the file I've created:
>    -
>    -  I've changed station_info to a 2D char array (as far as I
>    understand, this is just some extra info and it shouldn't make a difference
>    that I changed it to be a char/String(2D)?)
>    -  I miss a few long_names, and a few standard names are not the
>    "correct" standard names, but I can't figure out why this is not working.
> All seems nice so far, but when I try to read this netCDF-file with
> ToolsUI 4.3, I get this error message:
>    - Can't open
>    - NestedTable: cant find variable time for coordinate type Time
>    - NestedTable: cant find variable lat for coordinate type Lat
>    - NestedTable: cant find variable lon for coordinate type Lon
>    - Table Structure(record) featureType POINT: lat/lon/time coord not
>    found
>    - Failed to find FeatureDatasetFactory datatype=ANY_POINT
> Could the problem have something to do with the following comment in
> the "Short guide to writing files using CF-1.6 Discrete Sampling Features
> Conventions", under 9.5: "CDM: A variable representing the instance id is
> required, indicated by an attribute named cf_role, which follows all the
> CF rules above."
> It is absolutely not a requirement that the file is read by ToolsUI 4.3,
> but the fact that it can't be read from there probably indicates that
> something is wrong with the format (ncWMS can't read the file either).
> I'm not sure if it makes any difference to show the code here, but here is
> the method that writes to the netCDF file: (and
> yes, I know NetcdfFileWriteable is deprecated, but in my opinion, your
> documentation is quite difficult to use, and the "latest" examples (
> ) seems
> to be using this class)
> Any help with this problem would be greatly appreciated :)
> Many Thanks,
> Aleksander Vines
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