Re: 20051220: NcML Aggregation in THREDDS

• To: Bjørge Solli <bjorge.solli@xxxxxxxx>
• Subject: Re: 20051220: NcML Aggregation in THREDDS
• From: John Caron <caron@xxxxxxxxxxxxxxxx>
• Date: Tue, 03 Jan 2006 13:32:30 -0700

Bjørge Solli wrote:

John Caron wrote:

Bjørge Solli wrote:

John Caron wrote:

Unidata Support wrote:

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To: support@xxxxxxxxxxxxxxxx
From: =?ISO-8859-1?Q?Bj=F8rge_Solli?= <bjorge.solli@xxxxxxxx>

I am currently rewriting our xml-files to use the new aggregation functionality in Thredds 3.4. I have looked over all the documentation I could find on thredds and NcML but still have one unansvered Q. Hope you can help:

In the old version we used AggServer with an xml-statement like this:
...

<aggregation serviceName=".." aggType=".." varType=".." varUnit".." dateFormat="yyyy/M/d:hh:mm:ss z"> <fileAccess urlPath="long_name_b20030604_f200305289999.nc" coord="2003/05/28:00:00:00 GMT" />

   ...
...

My remaining Q is where I should write dateFormat now. I have something like this:

...
<variable name="time" type="int" shape="time">
   <attribute name="units" value=".." />
   <attribute name="_CoordinateAxisType" value="Time" />
</variable>

Here you are defining a time coordinate of dataType "int"

I see I omitted the units-value, it is "secs since 1970-01-01 00:00:00". This is a value I don't think my research coworkers want to change since I understand it is some standard in their field. The one in charge are on holidays, so will have to wait till he's back for the definite answer.

yes thats a udunit string, which thredds also uses.

but if you use this, then you must write the correct integer values in the coord field.

Thankyou very much for the advice.

I am wondering if there exist a document with all the allowed attribute names, like "_CoordinateAxisType". The xsd-schemas for netcdf/thredds does noe mention this as far as I can see. nor any other documents I have found so far.

Thanks.

Any attributes can be added to a Netcdf file. The _CoordinateAxis are special 
because they allow higher layers of the library to understand what the data 
means. These are documented at:

http://www.unidata.ucar.edu/software/netcdf-java/CoordinateAttributes3.html