[CF-metadata] Reverse-time trajectory

From: Jonathan Gregory <j.m.gregory>
Date: Fri, 11 May 2012 17:39:33 +0100

Dear Richard

Auxiliary coordinate variables don't have to be monotonic. That's the usual
rule for them, and the reason for what it says in H.2.1. To require them to
be monotonic would be a new rule. I think it would be a specific requirement
for sect 9. That is, you could say, if it's a timeseries feature type, the time
coordinate must be monotonic, even if it's an aux coord var. However, I don't
think you'd want to require other aux coord vars to be monotonic, such as lat,
lon and alt in the same example. So this extra requirement of monotonicity
would be for particular coordinate types in particular feature types.

Is this necessary? Also, is it desirable? Currently, it is possible for the
times to be stored disordered in the index ragged array representation, for
instance. That might be convenient, since that representation is expected to
be used when data is written as it arrives, and it might not arrive in the
right order. Would you want to prohibit this by requiring time to be monotonic
in H.2.5, for example?

Best wishes

Jonathan
Received on Fri May 11 2012 - 10:39:33 BST