NJ22 and WRF data

[John Caron]

Robert B. Schmunk wrote:
> 
> On Jun 1, 2007, at 17:53, John Caron wrote:
> 
> John, Thanks for the info.
> 
>> If you read through NetcdfFile class, you get the raw data.
>>
>> If you read through NetcdfDataset(enhance=true), you get the extra 
>> stuff. The "scientifiic data types" like Grid always use this mode.
> 
> Checking back into my own library, I see that I'm always using 
> NetcdfDataset.acquireFile (String,CancelTask).
> 
> The API for that method doesn't say whether the result is always
> enhanced, as does acquireDataset(String,CancelTask), but since
> I'm getting the extra stuff, it mus be.

yes, thats the default

> 
>> NetcdfDataset looks for a "CoordinateSystemBuilder" that recognizes 
>> that dataset, eg ucar.nc2.dataset.conv.WRFConvention class. This is 
>> the class that adds the coordinate variables, etc, by understanding 
>> that particular files' metadata, in WRF case, I think its all in the 
>> global attributes.
> 
> Despite the lack of a global "Conventions" attribute, I
> figured that it must be something in the global attributes.
> The variables in the sample dataset didn't seem to have any of
> the usual dimensions or attributes that I am used to seeing
> (see below), which usually make it self-evident what to do
> even if there is no convention tag.
> 
>> WRF continues to be a hard one to get right, there's a few flavors of 
>> it, the projection info is fishy, etc. If you send me a sample file I 
>> might be able to figure out why things aren't working out.
> 
> The file's really big, so I would have to e-mail you directions
> on how to download it. But belatedly I have found the webpage at
> http://www.unidata.ucar.edu/software/netcdf/examples/files.html
> 
> The sample file I have received includes metadata that looks
> substantially like (if not the same as) the sample WRF output
> that is the 5th item from the bottom of that webpage.
> 
> I have also added some diagnostic output to my code to check for
> coordinate information which I have never tested for before.
> Previously, I merely queried the CoordinateSystem if there was a
> lon axis and a lat axis. To deal with WRF data, it looks like
> I need to start querying for the existence of geoX and geoY
> axes and a CoordinateTransform.

that's it!

let me know if you have any problems....

> 
> rbs
> 
> 
> -- 
> Robert B. Schmunk, rschmunk at giss.nasa.gov
> NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025