[CF-metadata] CF standard_names for sea water pressure and sound intensity

From: Jonathan Gregory <j.m.gregory>
Date: Fri, 1 Apr 2005 11:21:16 +0100

Dear Roy

> In my experience ADCP acoustic echo intensity (sometimes termed acoustic
> backscatter) is either given as an absolute measurent in decibels or as
> a proportion of the transmitted signal, usually expressed as a
> percentage.
Thanks. These should have different standard names as they are different
quantities, even though both dimensionless.

> Sea pressure is a real can of worms.....
> f both of these types of measurement carry the
> same standard name label, great care needs to be taken that the mooring
> configuration is held somewhere else in the metadata in a form where it
> can be used by data discovery portals.
Yes. I think that a given quantity, however measured, should have the same
standard name. This is because the main purpose of standard names is to
identify which variables are comparable. But the method by which the quantity
has been derived should be recorded in other attributes (such as source) of the
data variable. These attributes are not currently standardised but they could
be for particular purposes, I'm sure. How to describe various kinds of
measurement is not something I know anything about (though you do of course!)
and would not like to make any proposals myself, but they would be welcome.

For model data, similarly, such attributes can be used to record info
identifying the model and integration. There are projects on systematising
this kind of metadata, outside CF (e.g. the Earley suite in GO-ESSP).

> It goes without saying that it is just as important to ensure that CTD
> data sets, where sea pressure is often included as the z spatial
> co-ordinate, are distinguished from sea level data sets. Otherwise our
> sea level user will be absolutely indundated by false hits.
Right. Pressure expressed as depth would have a different standard name
from pressure expressed as pressure, since the units are different. Sea level
is another quantity with its own set of standard names, although it has the
same units as depth.

Best wishes

Jonathan
Received on Fri Apr 01 2005 - 03:21:16 BST