Re: [thredds] How to set up best time series aggregation in THREDDS

  • To: Tor Nordam <Tor.Nordam@xxxxxxxxx>
  • Subject: Re: [thredds] How to set up best time series aggregation in THREDDS
  • From: Ryan May <rmay@xxxxxxxx>
  • Date: Wed, 4 Mar 2015 16:34:48 -0700
Tor,

Sorry you're having problems (and sorry it took you sending a second time
to get a response).  I'm not sure you're doing anything wrong: there are
some problems with FMRC collections that we know about, and FMRC will be
undergoing some significant work in the near-ish future to address these
(based on lessons learned from making collections of GRIB files).

However, this feels like there should be a simple fix (something going
weird when converting to double). What version of THREDDS are you running?
Also, can you send me or point me to some problematic data?

Thanks,

Ryan

On Tue, Mar 3, 2015 at 3:12 AM, Tor Nordam <Tor.Nordam@xxxxxxxxx> wrote:

>  Hi,
>
>
>
> I'm trying to set up a Forecast Model Run Collection using THREDDS. I have
> a collection of netCDF files, where the time at which the simulation was
> run is part of the filename:
>
>
>
> forecast_yyMMddHHmm.nc
>
>
>
> In the files, the time variable is an integer, and gives time as number of
> hours since a given date. This date is the same in all my files. Since the
> times are given in integer hours, there should be absolutely no uncertainty
> as to whether two timesteps are the same.
>
>
>
> However, when the THREDDS server presents this as an FMRC using the "best"
> model (for a given timpstep, it always serves data from the most recently
> performed simulation), it converts the time variable to a double, and
> somehow manages to present some timesteps which are actually the same as
> slightly different. For example, all of these are actually the same in my
> data, yet are presented as three different timesteps:
>
>
>
> -65.10000033333334, -65.10000033333333, -65.1
>
>
>
> The reason that the numbers are not whole hours is that the server also
> changes the reference point for the time axis from that specified in my
> files, to the simulation run time of the first file. This is fair enough,
> if only the data would be presented correctly.
>
>
>
> Interestingly, if I restart the thredds server, it manages to read and
> correctly present the files that are there at the time of restart, but
> later on, if it does a rescan triggered by the cron expression in the xml
> file, it doesn't get the timesteps right.
>
>
>
> Any suggestions as to what I'm doing wrong?
>
>
>
> The dataset definition in the xml-file looks like this:
>
>
>
>   <dataset name="FMRC Example">
>
>     <featureCollection name="BOM" featureType="FMRC" harvest="true"
> path="BOM">
>
>       <metadata inherited="true">
>
>         <serviceName>fmrcServices</serviceName>
>
>         <dataFormat>netCDF</dataFormat>
>
>         <documentation type="summary">Example BOM</documentation>
>
>       </metadata>
>
>
>
>       <collection spec="/system/data/forecast_#yyMMddHHmm#.*\.nc$"/>
>
>       <update startup="test" rescan="0 0/10 * * * ? *" trigger="allow"/>
>
>       <fmrcConfig regularize="false" datasetTypes="Best"/>
>
>     </featureCollection>
>
>   </dataset>
>
>
>
>
>
> Thanks,
>
> Tor
>
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>



-- 
Ryan May
Software Engineer
UCAR/Unidata
Boulder, CO
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