[CF-metadata] Standard names for altimeter data

From: Jonathan Gregory <j.m.gregory>
Date: Tue, 22 Aug 2006 19:07:14 +0100

Dear Olivier and all

I tend to agree with Olivier that sea surface height above sea level, geoid
and ellipsoid are three different quantities needing distinct standard names.
However it is also true that various ellipsoids are available and one might
need to specify which one. I don't think this should be done in the standard
name as that would lead to too many names. Roy is right this has come up
before and not been solved. I think this is a standard name parameter, of
which other examples are the reference pressure for potential quantities,
the criterion of the temperature or density difference from the surface which
defines a mixed layer, the reference values for things in decibels, the
wavelength of photosynthetic radiation. We have still not agreed a way to store
such parameters. My own suggestion is to use scalar coordinate variables, but
alternatives are to define a new attribute or to use ancillary data variables.

So I'd agree that we should add this name
sea_surface_height_above_reference_ellipsoid

I also agree there is need for geostrophic velocities calculated in various
ways. However, doesn't geostrophic velocity mean, by definition, that you are
calculating it relative to the geoid (a geopotential surface)? In that case
I assume that use of mean sea level or ellipsoid is an approximation, so you
could say
surface_Xward_sea_water_geostrophic_velocity X=east,north
for the case of using the geoid and
surface_Xward_sea_water_geostrophic_velocity_assuming_sea_level_for_geoid
surface_Xward_sea_water_geostrophic_velocity_assuming_reference_ellipsoid_for_geoid
for the other cases. What do you think?

Best wishes

Jonathan
Received on Tue Aug 22 2006 - 12:07:14 BST