[thredds] GRIB files, featureCollection, mixed tables and ncml

• To: THREDDS community <thredds@xxxxxxxxxxxxxxxx>
• Subject: [thredds] GRIB files, featureCollection, mixed tables and ncml
• From: Roy Mendelssohn - NOAA Federal <roy.mendelssohn@xxxxxxxx>
• Date: Mon, 25 Mar 2013 12:02:39 -0700

HI All:

We are having again having a problem that arose a couple of months ago with 
aggregating our grub files using <featureCollection type="GRIB">.  The problem 
arises because we get the following error when trying to access the aggregation:

> Error {
>     code = 500;
>     message = "Variable name (pres_msl) must be unique within Group ";
> };

and this problem is caused by the following  (thanks Ethan et al. for figuring 
this out):

> 
> it looks like the files are using two different versions of the same grib 
> table. In the wgrib output for some files says:
> ...
> center 58 subcenter 0 process 58 Table 2 scan: WE:SN winds(N/S)
> ...
> 
> but for some others:
> ...
> center 58 subcenter 0 process 58 Table 3 scan: WE:SN winds(N/S)

Now my question has to do with how your grib reader works, how that interacts 
with featureCollection, and how ncml files are viewed. What if for each file I 
created an ncml file that created a new variable that is basically the same one 
in the grib file, but because it is "new" it wouldn't be seen as different .  
Now my question is how would the resulting virtual file be viewed by TDS.  
Would it still be seen as a "grib" file and therefore aggregated using 
featureCollection, or is it now viewed as a netcdf file and aggregated using a 
aggregation scan, or will this not work at all?

We are supplied the files, and unfortunately don't have a good capability to 
rewrite the grib files, so are looking for a workaround.  

Thanks,

-Roy

**********************
"The contents of this message do not reflect any position of the U.S. 
Government or NOAA."
**********************
Roy Mendelssohn
Supervisory Operations Research Analyst
NOAA/NMFS
Environmental Research Division
Southwest Fisheries Science Center
1352 Lighthouse Avenue
Pacific Grove, CA 93950-2097

e-mail: Roy.Mendelssohn@xxxxxxxx (Note new e-mail address)
voice: (831)-648-9029
fax: (831)-648-8440
www: http://www.pfeg.noaa.gov/

"Old age and treachery will overcome youth and skill."
"From those who have been given much, much will be expected" 
"the arc of the moral universe is long, but it bends toward justice" -MLK Jr.

• Follow-Ups:
  • Re: [thredds] GRIB files, featureCollection, mixed tables and ncml
    • From: John Caron