[CF-metadata] new standard name request for pH

From: Jonathan Gregory <j.m.gregory>
Date: Mon, 18 May 2009 08:32:05 +0100

Dear John

I agree that

> "there are several systems of sea water
> chemistry (or its analogs) within which pH is measured or computed."
> I would say it is the chemical systems that vary, not merely the
> measurement technique.

could mean that the different pH scales are different geophysical quantities
and therefore need different standard names. You also say

> My non-expert impression is that the notion of pH is fairly well
> defined, but that different chemical systems will produce different pH
> measurements or calculated values, through no failure of the core
> definition of pH.

I am not an expert either, of course, but what I have read in this discussion
suggests to me that the notion of pH is actually inherently dependent on the
chemical system. These different scales are therefore *not* measuring the same
quantity, given the same sample of sea water, but somewhat similar quantities
that have distinct definitions.

I agree that it is not always possible to find a name that non-experts will
understand. For instance, atmosphere_sigma_coordinate tells a non-expert that
it is a kind of atmosphere coordinate, but if you don't know what sigma means,
you have to look at the definition. In many or most cases, however, we have
managed to find names that are somewhat more self-explanatory. That is why I
asked whether there were any more informative alternatives for "total scale"
and "sea water scale", because these terms are jargon. They have a precise
meaning, and they are used for convenience, but they are uninformative to
non-experts.

If we are to use these phrases in the standard name, I'd like to join them up
with some extra phrase to make their status clearer e.g.
sea_water_pH_defined_by_total_scale or _according_to_total_scale.

Personally, I'd still prefer an alternative if anyone knows any! I think a
workable alternative is one which would convey the meaning to an expert. That
is, it would be a phrase to which an expert would say, "Ah, you mean total
scale, of course!" The expert would probably go on to say, "Well, why didn't
you say total scale, then? It would be much clearer, and it's what is always
said." The answer to that would be that the chosen phrase would be more
informative to non-experts, if we had chosen it well. The definition would
confirm that it meant "total scale".

Best wishes

Jonathan
Received on Mon May 18 2009 - 01:32:05 BST