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Re: Grads GDS / Re: GRIB Aggregation



We have had the NARR on GDS for quite some time :
http://nomads.ncdc.noaa.gov:9091/dods/NCEP_NARR_DAILY
GDS works very well with GRIB data in general.
Our particular goal is to get it on TDS due to its suporior metadata
handling and WCS service.

If it is possible to create hooks that allow TDS to read and import
data/metadata from a source OPeNDAP URL, similar to what the Live Access
Server does... that would be outstanding.  May pose an easier task to
implement as well.

-Dan


Rob Cermak wrote the following on 6/14/2006 6:50 PM:
> Dan,
> 
> The Grads GDS OPeNDAP server is suppose to work with GRIB files.  The
> large unknown is if TDS can then aggregate the data across the Grads GDS
> server.  To help answer that is to see if TDS can aggregate across maybe
> one of the NOMADs GFS servers?  I'm pretty sure they are using the Grads
> GDS server.
> 
> http://www.iges.org/grads/gds/
> 
> Rob
> 
> On Tue, June 13, 2006 2:28 pm, dan.swank wrote:
> 
>>Ethan:
>>Understood.  consider this a wish-list then :)
>>-Dan
>>
>>Ethan Davis wrote the following on 6/13/2006 6:22 PM:
>>
>>>Hi Dan,
>>>
>>>Evidently, aggregation of GRIB data may not be working. I thought since
>>>GRIB files are read by the netCDF-java library it would just work but I
>>>just heard that there may be some issues with aggregating GRIB involving
>>>how the underlying code writes indexes into the GRIB files. We'll have
>>>to wait till John is back from vacation for a more detailed
>>>answer/explanation.
>>>
>>>Sorry for the mistake.
>>>
>>>There currently isn't a way to have a single scan element scan a set of
>>>directories.
>>>
>>>I believe the underlying netCDF-java code that reads GRIB files should
>>>result in fairly well-formed, CF (I think) compliant netCDF views of the
>>>dataset. Not sure how this would be affected by aggregation.
>>>
>>>Ethan
>>>
>>>dan.swank wrote:
>>>
>>>
>>>>Ethan:
>>>>
>>>>The NARR is a reanalysis, so it don't have forecast times.  I would be
>>>>a
>>>>simple 03 hr chain (00 hr fct time) spanning 26 years.
>>>>
>>>>See an existing GDS subset aggregation:
>>>>http://nomads.ncdc.noaa.gov:9091/dods/NCEP_NARR_DAILY/narr-a_221_tmpprs.subset.info
>>>>
>>>>This will give a sense for the nature of the beast.
>>>>
>>>>The directory structure is set up as such:
>>>>http://nomads.ncdc.noaa.gov/data/narr/
>>>>
>>>>
>>>>Heres the TDS aggregation I set up while experimenting yesterday, on a
>>>>non-related dataset:
>>>>
>>>>  <dataset name="OceanWinds Test Daily Aggregation"
>>>>      ID="test/dailyagg" urlPath="test/agg">
>>>>    <serviceName>allTest</serviceName>
>>>>    <netcdf
>>>>xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
>>>>     <aggregation dimName="time" type="joinNew">
>>>>       <variableAgg name="wind" />
>>>>       <scan dateFormatMark="#yyyyMMdd"
>>>>location="/eclipse1a/ftp/pub/seawinds/SI/daily/netcdf/1980s/"
>>>>suffix=".nc" />
>>>>       <scan dateFormatMark="#yyyyMMdd"
>>>>location="/eclipse1a/ftp/pub/seawinds/SI/daily/netcdf/1990s/"
>>>>suffix=".nc" />
>>>>       <scan dateFormatMark="#yyyyMMdd"
>>>>location="/eclipse1a/ftp/pub/seawinds/SI/daily/netcdf/2000s/"
>>>>suffix=".nc" />
>>>>     </aggregation>
>>>>     <variable name="time" orgName="time">
>>>>       <attribute name="long_name" value="Days"/>
>>>>       <attribute name="units" value="days since 1987-07-09" />
>>>>     </variable>
>>>>    </netcdf>
>>>>  </dataset>
>>>>
>>>>
>>>>Would this automatically detect the source of data were GRIB rather
>>>>than
>>>>NetCDF?  and it seems like you need to set the <scan> on each
>>>>individual
>>>>directory... Doing so the way NARR is set up would create one chunky
>>>>configuration file.  Is there anyway to have this scan a pattern
>>>>(YYYYMM/YYYYMMDD) of directories?
>>>>
>>>>I understand GRIB requires a certain amount of "supplemented" metadata
>>>>for complience.  Where do you enter this?
>>>>
>>>>-Dan
>>>>
>>>>
>>>>Ethan Davis wrote the following on 6/13/2006 1:21 PM:
>>>>
>>>>
>>>>
>>>>>Hi Dan,
>>>>>
>>>>>Aggregation should work the same for GRIB as for netCDF files. The
>>>>>issue
>>>>>would be how your GRIB files are structured and how you want to
>>>>>aggregate them. Our GRIB files each contain one full model run (all
>>>>>parameters, all forecast times). We haven't tried aggregating beyond
>>>>>that.
>>>>>
>>>>>We have started tracking what is available for the NCEP models on our
>>>>>server. This is from the TDS 3.8 announcement (with links updated):
>>>>>
>>>>>   We also are now tracking detailed inventory of NCEP model output,
>>>>>eg:
>>>>>
>>>>>http://motherlode.ucar.edu:8080/thredds/modelInventory/model/NCEP/NAM/CONUS_12km/
>>>>>
>>>>>
>>>>>   These are all linked from the "collection dataset" pages; For
>>>>>   example from
>>>>>
>>>>>http://motherlode.ucar.edu:8080/thredds/catalog/model/NCEP/NAM/CONUS_12km/catalog.html
>>>>>
>>>>>
>>>>>   choose the top "CONUS_12_km" link, then choose "Available
>>>>>Inventory"
>>>>>   Documentation.
>>>>>
>>>>>One idea for this work is to eventually provide access to alternate
>>>>>datasets, for instance, a dataset that contains all the 3hr forecast
>>>>>times from the different runs, or one that contained all the 12Z valid
>>>>>times from the different runs. Tracking these detailed inventories is
>>>>>just the first step but aggregation and alternate groupings of the
>>>>>data
>>>>>is pretty interesting to think about.
>>>>>
>>>>>How are your GRIB files structured and what kind of aggregation where
>>>>>you thinking about?
>>>>>
>>>>>Ethan
>>>>>
>>>>>dan.swank wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>Hello,
>>>>>>
>>>>>>I've been tinkering with the TDS aggregation capabilities and they
>>>>>>work
>>>>>>quite well for NetCDF data, however, I can't seem to find anything in
>>>>>>the docs regarding aggregating GRIB.
>>>>>>We want to get The NARR dataset which we have here at NCDC-NOMADS on
>>>>>>the
>>>>>>TDS.  It consists of hundreds of thousands of 50 Mb + GRIB files in a
>>>>>>YYYYMM/YYYYMMDD tree.
>>>>>>  Just scouting for a quick answer here:
>>>>>>Is aggregating the NARR GRIB currently feasable with the current
>>>>>>release
>>>>>>of TDS?  If so, do any docs exist which could give me a starting
>>>>>>point?
>>>>>>Converting it to NetCDF will not be possible (volume).
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>--
>>Dan Swank <address@hidden>
>>NOMADS Project:  Software & Data Management
>>Contractor - STG, Incorporated
>>Veach-Baley Federal Building
>>151 Patton Avenue
>>Asheville, NC 28801-5001
>>Phone: 828-271-4007
>>
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> 
> 
> 

-- 
Dan Swank <address@hidden>
NOMADS Project:  Software & Data Management
Contractor - STG, Incorporated
Veach-Baley Federal Building
151 Patton Avenue
Asheville, NC 28801-5001
Phone: 828-271-4007

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