Re: [thredds] Aggregation of virtual datasets

• To: tnb@xxxxxxxxxxxxxxxx
• Subject: Re: [thredds] Aggregation of virtual datasets
• From: Rich Signell <rsignell@xxxxxxxx>
• Date: Thu, 30 Dec 2010 14:09:35 -0500

I would try time aggregation on the inside loop.  Something like this:

<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 type="union">
   <!-- SSH -->
   <netcdf location="/data/IPCC/20c3m/ocn/mo/zos/ssh_1970_2000.nc"/>
   <!-- SST -->
   <netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
    <aggregation dimName="time" type="joinExisting">
     <netcdf location="/data/IPCC/20c3m/ocn/mo/thetao/sst_1970_1980.nc"/>
     <netcdf location="/data/IPCC/20c3m/ocn/mo/thetao/sst_1980_1990.nc"/>
     <netcdf location="/data/IPCC/20c3m/ocn/mo/thetao/sst_1990_2000.nc"/>
    </aggregation>
   </netcdf>
   <!-- SAL -->
   <netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
    <aggregation dimName="time" type="joinExisting">
     <netcdf location="/data/IPCC/20c3m/ocn/mo/so/sal_1970_1980.nc"/>
     <netcdf location="/data/IPCC/20c3m/ocn/mo/so/sal_1980_1990.nc"/>
     <netcdf location="/data/IPCC/20c3m/ocn/mo/so/sal_1990_2000.nc"/>
    </aggregation>
   </netcdf>
  </aggregation>
 </netcdf>
</dataset>

On Tue, Dec 28, 2010 at 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
>
>
>
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-- 
Dr. Richard P. Signell   (508) 457-2229
USGS, 384 Woods Hole Rd.
Woods Hole, MA 02543-1598

• References:
  • [thredds] Aggregation of virtual datasets
    • From: tnb