[CF-metadata] Timeseries of station data

From: Jonathan Gregory <j.m.gregory>
Date: Fri, 25 Jul 2003 13:01:02 +0100

Dear Juerg

> consider the following example:
>
> dimensions:
> station = 11 ;
> time = 2 ;
> max_len_id = 10 ;
> vec_dim = 4 ;
>
> float a_vector(station, vec_dim) ;
> char station_id(station, max_len_id) ;
> ...
>
> How can the application determine that (station) is a spatiotemporal dimension,
> but (max_len_id) and (vec_dim) are non-spatiotemporal dimensions?

Since station_id is an auxiliary coordinate variable, it should be named in
the coordinates attribute. In 6.1, we have "An application processing the
variables listed in the coordinates attribute can recognize a labeled axis by
checking whether or not a given variable contains character data." In general
all the dimensions of an auxiliary coordinate variable must be dimensions of
the data variable, but there is an exception for string arrays. In the
conformance requirements for section 5, we say "The dimensions of each
auxiliary coordinate must be a subset of the dimensions of the variable they
are attached to. An exception is a label variable which will have a trailing
dimension for the maximum string length." Hence, because station_id is of
character type, you know that its trailing dimension max_len_id is not a
spatiotemporal dimension.

I am not sure what a_vector(station, vec_dim) could be. If vec_dim is not a
dimension of the data variable, a_vector would be illegal as an auxiliary
coordinate variable.

You can test the legality of the file by running the conformance checker on
it.

Best wishes

Jonathan
Received on Fri Jul 25 2003 - 06:01:02 BST