Hi Nan, Roy and John,
Thanks all for your comments on this. I agree that the data variable
will give the information regarding what kind of waves are being
described, whether they be at the sea-surface, at the thermocline, or
indeed whether we are talking about something like electromagnetic
waves. If the situation arises where we clearly do need a more specific
frequency name, then one can always be introduced. I think we have
converged on the name 'wave_frequency' and I will make it an alias for
sea_surface_wave_frequency at the next update of the standard name
table.
Best wishes,
Alison
------
Alison Pamment Tel: +44 1235 778065
NCAS/British Atmospheric Data Centre Fax: +44 1235 446314
Rutherford Appleton Laboratory Email: J.A.Pamment at rl.ac.uk
Chilton, Didcot, OX11 0QX, U.K.
> -----Original Message-----
> From: Roy Lowry [mailto:rkl at bodc.ac.uk]
> Sent: 01 April 2008 06:13
> To: Pamment, JA (Alison); ngalbraith at whoi.edu
> Cc: cf-metadata at cgd.ucar.edu
> Subject: Re: [CF-metadata] FW: new standard_names forvariables
> concerningseasurface waves
>
> Hi Nan,
>
> I missed the point that it was a co-ordinate variable. Now I
> understand I totally agree with wave_frequency.
>
> Cheers, Roy.
>
> >>> Nan Galbraith <ngalbraith at whoi.edu> 3/31/2008 5:08 pm >>>
>
> Thanks, Alison. Wave_frequency would be better, although it
> implies, to me, the frequency of wave peaks where we really
> could use a term for a coordinate parameter of anything that
> can be reported in the frequency domain. So, I'm not sure why
> 'frequency' itself isn't sufficient in this case, other than a
> possible conflict with sound frequency ... although its a stretch
> to see how these could be mistaken for one another. A specific,
> non-coordinate parameter like brunt_vaisala_frequency_in_air
> should of course keep its more definitive standard name.
>
> > Don't forget we can have internal waves (waves propagated on
> subsurface
> > density boundaries like thermoclines) as well as surface waves in
> water
> > bodies.
>
> Yes, I guess that's my point: why would we need a separate
> frequency coordinate parameter for frequency of internal
> waves? The meaning of the coordinate parameter is the same
> in both cases, and the standard name of the measured parameter
> explains itself.
>
> We don't specify the variable being measured when we use depth
> as a coordinate parameter in CF, so I'm not sure why this case
> should be different.
>
> > My working hypothesis is that optimum combination of detail and
> > generality is medium + property
>
> Mine is that it's a bad idea to provide information that might be
> misleading or conflicting in a NetCDF field when that information
> is contained in another field, the standard_name. In this case, the
> parameter's standard name, sea_surface_wave_variance_spectral_density,
> gives information about the quantity being reported, and the name of
> the coordinate parameter should contain exactly enough information
> to make the measured parameter definitively understood. If there is
> another standard name where this would not be the case, I haven't
> come across it. That's the strength of NetCDF, and we may as well
> take advantage of its strong points, since we put up with its weak
> points as well.
>
> Wave_frequency seems like a better alternative and a good compromise,
> to me.
>
> Cheers - Nan
>
>
> > >>> "Pamment, JA (Alison)" <J.A.Pamment at rl.ac.uk> 03/31/08 11:09 AM
> >>>
> > >
> > > One of our parameters is
> sea_surface_wave_variance_spectral_density,
> > > with coordinate variables time and frequency.
> > >
> > > Sea_surface_wave_frequency is an accepted standard name, but I
> > > would like to know why 'frequency' is not preferable, being more
> > > generic. As an analogy, we can use 'depth' as the coordinate
> variable
> > > for temperatures, and are not so specific as to require
> > > sea_water_temperature_depth. Is specifying sea_surface_wave
> > > really necessary, and might it not be misleading if the parameter
> > > is not actually "plain" sea_surface_waves?
>
> > I'm not an expert in this area myself, so I'm not quite sure what
> you
> > mean by "plain" sea_surface_waves. However, to respond to your
> general
> > point, I agree that sea_surface_wave_frequency is very specific.
> > The original proposal (see
> > http://www.cgd.ucar.edu/pipermail/cf-metadata/2006/000958.html) was
> for
> > wave_frequency and it was submitted along with quite a list of
other
> sea
> > surface wave names. I suspect that it was changed for consistency
> with
> > the other names. I think that we need to at least use the term
> > wave_frequency rather than simply 'frequency' because it is not
the
> > only kind of frequency in standard names. We have the names
> > sound_frequency, which could in fact be described by
wave_frequency,
> and
> > brunt_vaisala_frequency_in_air, which is a parameter that relates
to
> the
> > static stability of air and is useful for determining whether
> gravity
> > waves will be generated, for example, by flow over orography. I
> think
> > that we could use wave_frequency quite adequately for fluid
> dynamical
> > waves, sound waves and electromagnetic waves independent of the
> medium
> > in which they occur. Would you be happy with wave_frequency?
> >
> > Best wishes,
> > Alison
>
>
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Received on Tue Apr 01 2008 - 06:11:24 BST
