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Re: [thredds] Help with GRIB encoding - what is "reference time of data" ??

Hi Don:

On 11/26/2013 8:41 AM, Don Murray (NOAA Affiliate) wrote:

Hi John-

On 11/26/13 8:24 AM, John Caron wrote:

Thanks for your ideas, I hadnt considered leaving "reference time" as
otherwise undefined. The downside would be that GRIB will then be
different from, say, netCDF-CF forecast model collections.


Isn't "run time" a construct of the CDM/FMRC, not CF?  I don't see
reference to "run time" in the CF document.  If that's the case, you
could do whatever you want. ;-)
"run time" is intended to reflect the semantics of forecast models. Obviously still trying to figure out what that means ;) 

CF, as usual, lags behind a bit.




Examining the NCEP IDD feed, 13 out of 400K GRIB-2 records have this
feild set to 0, the rest to 1:

significanceOfReference
      0: count = 13
      1: count = 406196

Im not sure if these are miscoded or not. What do you think the
difference is between "Analysis" and "Start of Forecast" ?


It would be helpful to know what those 13 are to know if they are
miscoded.  I would imagine that a reanalysis grid might use analysis, or
perhaps the RTMA, but for either of those, I would expect there to be
more in your collection.


what do you think the difference would be and would it actually matter?



Do you have a script/code that can easily check this?  If so, share it
and I (and others) could run it over some of our grib collections.


where else would it be but in the undocumented ToolsUI ??

ToolsUI / Iosp / GRIB2 / GRIB2-Report

enter collection spec (eg Q:/cdmUnitTest/tds/ncep/.*.grib2)
choose "idProblems"
hit RedRaw ("Make report")
the "use Index" toggle will turn on/off details
i just added significanceOfReference in v4.4.0, which im hoping to release today. So once i do that you can give it a try. 

thanks,
John
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