[CF-metadata] stations and trajectories

John Caron caron at unidata.ucar.edu
Wed Jun 8 18:22:14 MDT 2005


Jonathan Gregory wrote:

>Dear John
>
>Stations
>  
>
>>If you want to store multiple trajectories in the file, CF doesnt 
>>explicitly say how to do that. The obvious solution might be to add a 
>>trajectory dimension. This has the limitation that you must store the 
>>same number of points for each trajectory.
>>    
>>
>
>Trajectories
>  
>
>>The current standard has the limitation that all stations have the same 
>>number of observations (time-series) and time coordinates. Mesonet 
>>station data, for example,  is often variable length with arbitrary time 
>>stamps.
>>    
>>
>
>In both cases, if the timeseries or trajectories have different lengths, is
>there any reason why you should not put them in separate variables with
>different time dimensions and coordinates? NetCDF-4 will help this by allowing
>more than one unlimited dimension.
>
>  
>
yes, thats a possibility, but if the time coordinates are arbitrary, you 
would have a separate variable for every station, which in some cases 
would not be practical.

>>There is no explicitly specified way to describe station information, eg 
>>a station  id, description, etc.
>>    
>>
>
>There is a method to associate such labels with stations in 6.1 of the
>standard. Standardised station IDs such as WMO station numbers could be used
>if that's appropriate (although use of codes makes the file less self-
>describing, so I think names are better).
>  
>
thanks, i hadnt seen that section before in this context.

i see that you have a string valued coordinate variable. Is the 
intention that be a unique identifier ?

In the case im trying to deal with, we have a unique id, a description 
and optionally a wmo id associated with each station. In general, one 
could have arbitrary information you want to associate with each station.




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