Re: [Fwd: Re: XYT and XYZT grid with only 1 X and 1 Y point in axis]



Hi Roland:

The problem is that the z coordinate doesnt have a "positive" attribute. I was assuming that it needed it for COARDS, but on closer read it is in fact optional, if the units have dimension of length, pressure, level, layer, sigma_level or another vaguely worded section that seems to allow a bunch more things.

Anyway, I have changed the code to follow the spec, but I fear that non-vertical coordinates will get misidentified as vertical. I would reccommend always using the "positive" attribute to disambiguate.


I agree that the spec is terribly vague and using the positive attribute is a good idea. More below.


Get the latest 2.2.10 release at
http://my.unidata.ucar.edu/content/software/netcdf-java/index.html


Yep, I got it.  Works great.


FYI, I would recommend using a convention for observation data, rather than using singleton latitude/longitude to create degenerate "grids". One that I have been working on is at

http://my.unidata.ucar.edu/content/software/netcdf-java/formats/UnidataObsConvention.html


Again I agree with you in principle. Jon Callahan in our group has begun working with this convention and some examples you provided. We're very impressed. Ferret can work with these data files quite well and the access is fast. In defense of the folks and NDBC, I think their needs pre-date the Unidata Obs Convention and I think what they've done is 1000x better than other attempts I've seen to cram observations into netCDF in some haphazard way. At least these files are usable as is. Even so, I will pass your comments along to the folks that create and manage these files. Perhaps there will be some tricks we can use from the jnc 2.2 code and/or NCML to massage these files into the Obs Convention.

theres nothing "wrong" with these as they stand, but they dont generalize to the case of multiple buoys in the same file.

i think in fact, nj22 can already read them into our ObsDataset interface (this is at a higher abstraction layer than the convention).



Can you send me a sample file with the depth dimsnion, so I can test in my stationObs reader ?


I'll see what I can do about getting you an example from NDBC. Meanwhile the only access I'm aware of for these files is through the DODS server. E.g. http://dods.ndbc.noaa.gov/cgi-bin/nph-dods/dods/adcp/41012/41012a2002.nc.

ill have a look, thanks


Roland