Dear Alison,
Thank you for your comments.
> > 2)
> >
ratio_of_x_derivative_of_ocean_rigid_lid_pressure_to_sea_surface_densit
> > y
> > N kg-1
> >
> >
> -----------------------------------------------------------------------
> > ---------
> > NB: x_derivative_of_ocean_rigid_lid_pressure is already a
> > standard_name,
> > and I'm proposing sea_surface_density in (1).
> >
> The relationship between this name and existing and proposed names is
> clear. The term ratio is certainly used in standard names. Therefore I
> think this name sounds reasonable (but please see the following
> comments).
>
> Looking at the standard name table entries for ocean_rigid_lid_pressure
> and x|y_derivative_of_ocean_rigid_lid_pressure which we introduced for
> the NEMO model in version 10 of the table, I see that we gave them
> canonical_units of N m-2 and N m-3 respectively. The usual practice in
> standard names is to write N m-2 as Pa which would make the second unit
> Pa m-1 and I think we should change the units of all three names in the
> table.
This is fine by me.
> Please note that this does not in any way prevent you from
> writing the quantities in a file using physically equivalent units. For
> the current proposal, I think we should write the canonical units as m
> s-2 which is exactly equivalent to N kg-1.
Fine again - and better, I suppose, since m and s are fundamental in SI
and N is derived.
> M s-2 is the unit of
> acceleration and I am wondering what is the physical interpretation of
> the quantity you propose - does it express an acceleration in your
> model?
>
Yes, it appears as a trend in the velocities.
With a free surface height, it actually appears as g*grad(SSH), so
perhaps a more suitable standard_name would be
product_of_acceleration_due_to_gravity_and_x_derivative_of_sea_surface_height_above_geoid [m s-2]
- but, apparently, acceleration_due_to_gravity (or anything like it) is
not a CF standard_name. So we may as well stick to what I suggested
before.
Regards,
Ian.
--
Ian Culverwell B-2-81 Ocean and Sea Ice Modelling
Met Office FitzRoy Road Exeter Devon EX1 3PB United Kingdom
Tel: +44 (0)1392 884017 Fax: +44 (0)1392 885861
E-mail: ian.culverwell at metoffice.gov.uk http://www.metoffice.gov.uk
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Received on Wed Feb 11 2009 - 07:01:19 GMT
