Dear Jonathon,
I think we have converged on the following suggested names:
sea_surface_wave_variance_spectral_density, units m2 s-1
sea_surface_wave_directional_variance_spectral_density, units m2 s-1
rad-1
sea_surface_wave_zero_upcrossing_period, units s
sea_surface_wave_frequency, units s-1 (Hz)
sea_surface_wave_from_direction, units degrees
sea_surface_wave_to_direction, units degrees
sea_surface_wave_significant_height, units m
sea_surface_wind_wave_zero_upcrossing_period, units s
sea_surface_swell_wave_zero_upcrossing_period, units s
I agree that it would be useful if the existing names (containing
wind_wave/swell_wave) were brought into line too, as aliases for
'sea_surface_' standards.
John
On Sat, 2006-06-03 at 14:11, Jonathan Gregory wrote:
> Dear John
>
> > Thanks for the comments. I agree that just 'wave' is ambiguous. I like
> > 'ocean_surface_wave' instead.
> I think I should have suggested sea rather than ocean, to be more general and
> consistent with other names, such as sea_surface_height. Would that be OK?
Yes.
>
> Maybe we should change the existing wind_wave and swell_wave to
> sea_surface_wind|swell_wave to be clearer about them.
Good idea.
>
> > > standard_name = "wave_spectrum_direction" ;
> > > standard_name = "direction_of_wave_velocity" ;
> > The reason for 2 directions was that one represents a coordinate
> > variable, and the other represents the principal wave direction (the one
> > associated with the peak in the energy spectrum). However, I think we
> > can use the 'cell_methods' here with 'wave_energy: maximum'.
> OK. So you're proposing just direction_of_[sea_surface_]wave_velocity now.
Yes.
>
> > >The units of m2 are not units of energy. Perhaps it's the square of
> > >the wave amplitude, or the RMS amplitude?
> > True. It is really a 'variance density spectrum' but wave modellers seem
> > to refer to this as an 'energy density spectrum'. A factor of (rho * g)
> > relates the two, so I have removed 'energy' from the name. Now I suggest
> > ocean_surface_wave_spectrum_density, units m^2 s-1 rad-1
> Why not put in "variance" explicitly, as I see you suggest later? This might be
> useful because it's always possible that one day someone might want a name for
> the energy spectrum (in energy units) or some other spectrum. I think
> wave_variance would be a reasonable name for the quantity in m2.
>
> I'm puzzled why this one is rad-1. In your original proposal it was the extra
> "directional" which made in rad-1, and I understood that. Should it be
>
> sea_surface_wave_variance_spectrum_density in m2 s-1
> sea_surface_wave_directional_variance_spectrum_density in m2 s-1 rad-1
>
Yes.
> One further minor point - would spectral be equally acceptable? If so it might
> be preferable because it's the word used for radiation. But if spectrum is
> always the term used, then it's better for this application.
Yes.
>
> > The 'zero up-crossing' period is a standard means of measuring wave
> > period. It is defined using the time the surface height passes upward
> > over the mean level. Other definitions of wave periods include peak and
> > mean. Peak could be defined using cell_methods ('wave_energy : maximum')
> and mean could also be defined with a cell_methods, which would make it
> precise since you have then to specify what is the independent variable
> over which the mean is calculated.
> >
> > ocean_surface_wave_zero_upcrossing_period, units s
> > ocean_surface_wave_frequency, units s-1 (Hz)
> > ocean_surface_wave_from_direction, units degrees
> > ocean_surface_wave_to_direction, units degrees
> > (Convention is for direction toward which energy travels for wave
> > spectra with frequency & direction, but the direction from which waves
> > are coming [like wind] in other contexts.)
> OK.
>
> > ocean_surface_wave_significant_height, units m
> The standard name table already has significant_height_of_wind_and_swell_waves,
> and corresponding terms for wind and swell separately. If no-one objects, we
> could make the existing name an alias for your new name, and swap round the
> others to make them sea_surface_wind|swell_wave_significant_height.
That would be good.
>
> > wind_wave_zero_upcrossing_period, units s
> > swell_wave_zero_upcrossing_period, units s
> OK. Perhaps with sea_surface_ prefixed, as suggested above.
>
> Best wishes
>
> Jonathan
> _______________________________________________
> CF-metadata mailing list
> CF-metadata at cgd.ucar.edu
> http://www.cgd.ucar.edu/mailman/listinfo/cf-metadata
Received on Wed Jun 07 2006 - 06:31:03 BST
