Re: [thredds] ncml aggreation- some variable attributes from the first file not getting carried over

  • To: Remon Sadikni <remon.sadikni@xxxxxxx>
  • Subject: Re: [thredds] ncml aggreation- some variable attributes from the first file not getting carried over
  • From: Upendra Dadi <Upendra.Dadi@xxxxxxxx>
  • Date: Tue, 28 Sep 2010 11:07:56 -0400
Thank you Remon for your time. The catalog.xml looks like this:
-------------------------------------------------------------------
<catalog version="1.0.1">
−
<service name="allServices" serviceType="Compound" base="">
<service name="dapService" serviceType="OPENDAP" base="/thredds/dodsC/"/>
<service name="httpService" serviceType="HTTPServer" base="/thredds/fileServer/"/>
<service name="wcsService" serviceType="WCS" base="/thredds/wcs/"/>
<service name="wmsService" serviceType="WMS" base="/thredds/wms/"/>
</service>
−
<dataset name="_ghrsst_L4_MED_EUR_ODYSSEA_2008" ID="pathfinder/testdata/ghrsst_catalog_test/_ghrsst_L4_MED_EUR_ODYSSEA_2008">
<serviceName>allServices</serviceName>
−
<metadata inherited="true">
<serviceName>allServices</serviceName>
</metadata>
−
<dataset name="aggregate__ghrsst_L4_MED_EUR_ODYSSEA_2008.ncml" ID="pathfinder/testdata/ghrsst_catalog_test/_ghrsst_L4_MED_EUR_ODYSSEA_2008/aggregate__ghrsst_L4_MED_EUR_ODYSSEA_2008.ncml" urlPath="pathfinder/testdata/ghrsst_catalog_test/_ghrsst_L4_MED_EUR_ODYSSEA_2008/aggregate__ghrsst_L4_MED_EUR_ODYSSEA_2008.ncml">
<dataSize units="Kbytes">43.7</dataSize>
<date type="modified">2010-09-16 21:27:02Z</date>
</dataset>
</dataset>
</catalog>
---------------------------------------------------------------------------------------------

The ncml file looks like this:
--------------------------------------------------------------------------------------------
<?xml version="1.0" encoding="UTF-8"?>
<netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
<remove type="attribute" name="creation_date"/>
<attribute name="start_date" type="string" value="2008-01-01 UTC" />
<attribute name="start_time" type="string" value="00:00:00 UTC" />
<attribute name="stop_date" type="string" value="2008-12-31 UTC" />
<attribute name="stop_time" type="string" value = "23:59:59 UTC" />
<aggregation dimName="time" type="joinExisting">
<netcdf id="001" location ="http://www.foo.com/20080101-EUR-L4UHRfnd-MED-v01-fv01-ODYSSEA.nc.bz2"; ncoords="1"/> <netcdf id="013" location ="http://www.foo.com//20080113-EUR-L4UHRfnd-MED-v01-fv01-ODYSSEA.nc.bz2"; ncoords="1"/> <netcdf id="014" location ="http://www.foo.com/20080114-EUR-L4UHRfnd-MED-v01-fv01-ODYSSEA.nc.bz2"; ncoords="1"/>
......
---------------------------------------------------------------------------------------------

Upendra



Remon Sadikni wrote:
Hi Upendra,

I do not know, but if you could also show the aggregation code in the catalog.xml file, we might see something, that causes the problem...

Regards,
Remon

On 09/28/2010 04:37 PM, Upendra Dadi wrote:
Hi,
I have a problem involving NcML aggregation. I have created an NcML aggregation file using joinExisting with aggregation over time.
The das for the first file in the aggregation file is:

-------------------------------------------------------------------------------

Attributes {
time {
String long_name "reference time of sst field";
String standard_name "time";
String axis "T";
String units "seconds since 1981-01-01 00:00:00";
}
lat {
String long_name "latitude";
String standard_name "latitude";
String axis "Y";
String units "degrees_north";
}
lon {
String long_name "longitude";
String standard_name "longitude";
String axis "X";
String units "degrees_east";
}
analysed_sst {
String long_name "analysed sea surface temperature";
String standard_name "sea_surface_temperature";
String type "foundation";
String units "kelvin";
Int16 _FillValue -32768;
Float64 add_offset 273.15;
Float64 scale_factor 0.01;
Int16 valid_min -300;
Int16 valid_max 4500;
}
......
......

--------------------------------------------------------
The das file for the aggregation file(NcML file) is:

--------------------------------------------------------------------------

Attributes {
lat {
}
lon {
}
time {
}
analysed_sst {
String _CoordinateAxes "time lat lon ";
String long_name "analysed sea surface temperature";
String standard_name "sea_surface_temperature";
String type "foundation";
String units "kelvin";
Int16 _FillValue -32768;
Float64 add_offset 273.15;
Float64 scale_factor 0.01;
Int16 valid_min -300;
Int16 valid_max 4500;
}
NC_GLOBAL {
String time.long_name "reference time of sst field";
String time.standard_name "time";
String time.axis "T";
String time.units "seconds since 1981-01-01 00:00:00";
String lat.long_name "latitude";
String lat.standard_name "latitude";
String lat.axis "Y";
String lat.units "degrees_north";
String lon.long_name "longitude";
String lon.standard_name "longitude";
String lon.axis "X";
String lon.units "degrees_east";
String Conventions "CF-1.0";
.....
.....

-------------------------------------------------------------------------

As you can see, the attributes for latitude, longitude and time have moved from the variables to the global attributes after the aggregation for some reason. Shouldn't they remain with the variables? The aggregation file is no longer CF compliant due to this. What is going on here?
Is it a THREDDS problem? Or is there away to correct this?

Upendra



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