[THREDDS #FUB-114946]: Understanding vertCoord behaviour with netcdf subset service

Fabulous, thanks for the feedback!

-Lansing

On 11/6/2013 8:27 PM, daryl herzmann wrote:
> New Client Reply: Understanding vertCoord behaviour with netcdf subset service
>
> Hi Lansing,
>
> Yup, you are right.  This was a goose chase and fixed in the latest
> release.  I'll see what NCDC says about updating.
>
> thanks,
>    daryl
>
> On Wed, 6 Nov 2013, Unidata THREDDS Support wrote:
>
>> Hi Daryl,
>>
>> I started to take a look at the phenomenon you are seeing, but I immediately 
>> noticed that the Thredds server you've referenced is running a very old 
>> version of the TDS - 4.2.10 from April of 2012.  We've done a lot of work 
>> since then, and there is a reasonable good chance that a bug contributing to 
>> the behavior has been fixed in a subsequent version of the TDS.
>>
>> Any chance you can convince them to upgrade?  We're gone all the way through 
>> 4.3.20, and are about to release 4.4.0.
>>
>> Cheers,
>>   Lansing Madry
>>   Unidata
>>   Boulder, Colorado
>>
>>> Hi Thredds Dudes,
>>>
>>> I was recently exchanging emails with NCDC about their thredds server and
>>> how it was handling vertCoord requests for the netcdf subset service.  I
>>> am really confused by the behaviour and perhaps there are bugs afoot here!
>>> Lets start this goose chase with the documentation:
>>>
>>> http://www.unidata.ucar.edu/software/thredds/current/tds/interfaceSpec/NetcdfSubsetService_4_3.html#Vertical
>>>
>>> "Subset on the vertical axis of a variable or variables with the same
>>> vertical levels may be done with the vertCoord parameter"
>>>
>>> Okay, so if I go here:
>>>
>>> http://mtarchive.geol.iastate.edu/thredds/ncss/grid/mtarchive/2013/11/04/gempak/model/2013110412_avn211.gem/pointDataset.html
>>>
>>> and put in '2' for the vertical level and TMPK_HGHT var, I get
>>>
>>> http://mtarchive.geol.iastate.edu/thredds/ncss/grid/mtarchive/2013/11/04/gempak/model/2013110412_avn211.gem?var=TMPK_HGHT&latitude=41.99&longitude=-93.61&temporal=all&time_start=2013-11-07T18%3A00%3A00Z&time_end=2013-11-14T12%3A00%3A00Z&time=2013-11-07T18%3A00%3A00Z&vertCoord=2&accept=csv&point=true
>>>
>>> lots of NaN !  Hmmm, if I change, vertCoord to blank
>>>
>>> http://mtarchive.geol.iastate.edu/thredds/ncss/grid/mtarchive/2013/11/04/gempak/model/2013110412_avn211.gem?var=TMPK_HGHT&latitude=41.99&longitude=-93.61&temporal=all&time_start=2013-11-07T18%3A00%3A00Z&time_end=2013-11-14T12%3A00%3A00Z&time=2013-11-07T18%3A00%3A00Z&vertCoord=&accept=csv&point=true
>>>
>>> still NaN...  If I then change vertCoord to 0, I get data!
>>>
>>> http://mtarchive.geol.iastate.edu/thredds/ncss/grid/mtarchive/2013/11/04/gempak/model/2013110412_avn211.gem?var=TMPK_HGHT&latitude=41.99&longitude=-93.61&temporal=all&time_start=2013-11-07T18%3A00%3A00Z&time_end=2013-11-14T12%3A00%3A00Z&time=2013-11-07T18%3A00%3A00Z&vertCoord=0&accept=csv&point=true
>>>
>>> but then if I add UREL_HGHT
>>>
>>> http://mtarchive.geol.iastate.edu/thredds/ncss/grid/mtarchive/2013/11/04/gempak/model/2013110412_avn211.gem?var=TMPK_HGHT&var=UREL_HGHT&latitude=41.99&longitude=-93.61&temporal=all&time_start=2013-11-07T18%3A00%3A00Z&time_end=2013-11-14T12%3A00%3A00Z&time=2013-11-07T18%3A00%3A00Z&vertCoord=0&accept=csv&point=true
>>>
>>> I get data, but the vertCoord[unit="m"] is now zero for everything.
>>>
>>> Looking back at the documentation, it has:
>>>
>>> Request: "Give me variable Temperature_pressure at a particular vertical
>>> level: 1000 mb*"
>>> Temperature_pressure                                                1000
>>> ?var=Temperature_pressure&vertCoord=1000
>>>
>>> so it would appear vertCoord is the value along the vertical axis and not
>>> the index along the axis?
>>>
>>> Any thoughts on this?  I understand that this is very complex problem to
>>> account for.
>>>
>>> thanks,
>>> daryl
>>>
>>> --
>>> /**
>>> * Daryl Herzmann
>>> * Assistant Scientist -- Iowa Environmental Mesonet
>>> * http://mesonet.agron.iastate.edu
>>> */
>>>
>>>
>>
>> Ticket Details
>> ===================
>> Ticket ID: FUB-114946
>> Department: Support THREDDS
>> Priority: Normal
>> Status: Open
>>
>>



Ticket Details
===================
Ticket ID: FUB-114946
Department: Support THREDDS
Priority: Normal
Status: Open