[CF-metadata] downward_air_velocity

From: Jonathan Gregory <j.m.gregory>
Date: Thu, 11 Sep 2014 17:26:49 +0100

Dear Jim

> Seems a shame that this wasn't originally handled with a standard
> name of 'vertical_air_velocity' (or some such) that required a
> 'positive' attribute. Both upward and downward could be covered with
> no confusion.

If it was a separate attribute, it
could be omitted, and probably sometimes would be (even if that was an error).
I expect you, like me, have experienced frustrations with analysing datasets
where the quantities are described but their sign conventions not stated.
With CF standard_names this problem cannot arise. It imposes a small cost by
increasing the number of standard_names that have to be defined, but it's
very easy to agree such pairs of standard_names, and of course it only
affects quantities that do have a sign, which is minority. So I don't think
it's a shame at all. :-) It was a deliberate decision (made 15 years ago),
which I think has been beneficial.

Best wishes

Jonathan
Received on Thu Sep 11 2014 - 10:26:49 BST