Jonathan:
(1)
At a conceptual level, I like your suggestions, but I do have a question ?
Why have you not used a "cell_measure" attribute in the event_energy data variable to associate this data variable with the event_area data variable as shown in example 7.3 in the CF standard (e.g. :cell_measures = "area: event_area" ?
Note that a lightning detection is actually a collection of events, but I thought it was best to work through the lightning detection product one piece at a time. There are other CF convention relevant complexities associated with this lightning detection product I have yet to communicate.
(2)
Should the CF convention standard be updated to state that a featureType of "point" can make use of cell constructs ? Currently chapter 7 starts "When gridded data does not represent ?..".
(Note that it may be useful for other discrete sampling geometry types to make use of cell constructs, but I know you are of the thinking to augment the standard on an as-needed basis.)
very respectfully,
randy
On Apr 10, 2012, at 5:20 PM, Jonathan Gregory wrote:
> Dear Randy
>
> Thanks for your further description. Now I agree with you and John that this
> is a point feature. I guessed wrongly from your first email that you were
> describing something like a timeseries. The file records a number of lightning
> events, each with an energy, area, location, time - have I understood
> correctly? In that case I suppose the logical structure of the data is
>
> float event_energy(event);
> event_energy:coordinates="time lat lon";
> event_energy:cell_methods="time: sum area: sum";
> float event_area(event);
> event_area:coordinates="time lat lon";
> event_area:cell_methods="time: sum area: sum";
> float time(event);
> time:bounds="time_bounds";
> float time_bounds(event,two);
> float lat(event);
> float lon(event);
>
> Is that right? The energy detected applies to a certain region of space-time,
> so I think "sum" is the appropriate cell_methods, rather than being precisely
> localised at a particular time and place, in which case "point" would be right.
> I have put the energy and the area of the event as the data variables, and the
> time and location as aux coord vars. You might wish to propose new standard
> names for the data vars.
>
> Best wishes
>
> Jonathan
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____________________________________
Randy C. Horne (rhorne at excaliburlabs.com)
Principal Engineer, Excalibur Laboratories Inc.
voice & fax: (321) 952.5100
url:
http://www.excaliburlabs.com
Received on Tue Apr 10 2012 - 16:12:48 BST
