Re: [thredds] Aggregation of virtual datasets

We use the Thredds catalog to produce

http://iridl.ldeo.columbia.edu/SOURCES/.WCRP/.CMIP3/

and that page has a number of useful links.

The original Thredds catalog is at

http://esgcet.llnl.gov/dap/ipcc4/?thredds

We occasionally find a problem, and a fair number of the time bounds have
some single precision noise that appeared in the conversion process, but
there is a lot of useful data there.  Both our service and the original use
the same user/password that you get in the first place to access the data,
i.e. IRI does not issue the password.

Benno



On Thu, Dec 30, 2010 at 3:28 PM, Rich Signell <rsignell@xxxxxxxx> wrote:

> Benno,
>
> On Thu, Dec 30, 2010 at 2:46 PM, Benno Blumenthal
> <benno@xxxxxxxxxxxxxxxx> wrote:
> > FYI - that data is already served aggregated at pcmdi
>
> Where?
>
> > one of the mistakes
> > that one needs to watch for is time coordinates (particularly time
> bounds)
> > where the units are different between the three files, e.g. each file
> starts
> > at time zero but that value has a different offset in the units.
>
> This case can be handled in NcML by adding timeUnitsChange="true" to
> the aggregation specification:
>
> <aggregation dimName="time" type="joinExisting" timeUnitsChange="true">
>
> -Rich
>
> >
> > On Dec 28, 2010 9:33 AM, <tnb@xxxxxxxxxxxxxxxx> wrote:
> >
> > Hi everybode!
> >
> > I would like to make a local server for some IPCC data and would like to
> > know if is there any way to aggregate (type "union") virtual data
> (construct
> > with aggregate "joinExisting") with netcdf files.
> >
> > Let me explain with an example:
> >
> > I have 3 variables, all monthly data, sea surface temperature, salinity
> and
> > sea surface height, each one in a diferent directory.
> >
> > SST are 3 files, sst_1970_1980.nc, sst_1980_1990.nc, sst_1990_2000.nc
> >
> > salinity are 3 files too, sal_1970_1980.nc, sal_1980_1990.nc,
> > sal_1990_2000.nc
> >
> > SSH is 1 file, ssh_1970_2000.nc
> >
> > Each variable have the same lon, lat axis and in total, all have 30 X 12
> =
> > 360 timesteps.
> >
> > I tried to do a nested aggregation, but it doesn t work...
> >
> >
> >  <dataset name="IPCC data" ID="ippc_agg" urlPath="ipcc/agg.nc">
> >    <serviceName>odap</serviceName>
> >    <netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2
> ">
> >    <aggregation dimName="time" type="joinExisting">
> >    <netcdf>
> >    <aggregation type="union">
> >      <netcdf location="/data/IPCC/20c3m/ocn/mo/thetao/sst_1970_1980.nc
> "/>
> >      <netcdf location="/data/IPCC/20c3m/ocn/mo/so/sal_1970_1980.nc"/>
> >    </aggregation>
> >    </netcdf>
> >    <netcdf>
> >    <aggregation type="union">
> >      <netcdf location="/data/IPCC/20c3m/ocn/mo/thetao/sst_1980_1990.nc
> "/>
> >      <netcdf location="/data/IPCC/20c3m/ocn/mo/so/sal_1980_1990.nc"/>
> >    </aggregation>
> >    </netcdf>
> >    <netcdf>
> >    <aggregation type="union">
> >      <netcdf location="/data/IPCC/20c3m/ocn/mo/thetao/sst_1990_2000.nc
> "/>
> >      <netcdf location="/data/IPCC/20c3m/ocn/mo/so/sal_1990_2000.nc"/>
> >    </aggregation>
> >    </netcdf>
> >    <netcdf>
> >    <aggregation type="union">
> >      <netcdf location="/data/IPCC/20c3m/ocn/mo/zos/ssh_1970_2000.nc"/>
> >    </aggregation>
> >    </netcdf>
> >    </aggregation>
> >    </netcdf>
> >  </dataset>
> >
> >
> > ... I expected that the aggregate data, agg.nc had 3 vars, sst, sal and
> ssh
> > and each one with a 360 timesteps axis. But what happens was that agg.nc
> > have only 2 vars, sst and sal and their time axis have 720 timesteps.
> >
> > I didn t find any information about how to do this kind of aggregation
> and
> > stay wondering how could it be done.
> >
> > Thanks for attention and happy new year for all!
> >
> > Tiago Bomventi
> >
> >
> >
> > _______________________________________________
> > thredds mailing list
> > thredds@xxxxxxxxxxxxxxxx
> > For list information or to unsubscribe,  visit:
> > http://www.unidata.ucar.edu/mailing_lists/
> >
> > _______________________________________________
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> >
>
>
>
> --
> Dr. Richard P. Signell   (508) 457-2229
> USGS, 384 Woods Hole Rd.
> Woods Hole, MA 02543-1598
>



-- 
Dr. M. Benno Blumenthal          benno@xxxxxxxxxxxxxxxx
International Research Institute for climate and society
The Earth Institute at Columbia University
Lamont Campus, Palisades NY 10964-8000   (845) 680-4450
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