Hi Jonathon and CF metadata list,
My responses are in-line below.
Andrew Walsh
----- Original Message -----
From: "Jonathan Gregory" <j.m.gregory at reading.ac.uk>
To: "andrew walsh" <awalsh at metoc.gov.au>
Cc: "Patrick Gorringe" <Patrick.Gorringe at utas.edu.au>; <greg at metoc.gov.au>;
"Mark Kulmar" <Mark.Kulmar at mhl.nsw.gov.au>; <cf-metadata at cgd.ucar.edu>; "Roger
Proctor" <Roger.Proctor at utas.edu.au>
Sent: Wednesday, October 13, 2010 03:09
Subject: [CF-metadata] Seeking new CF standard names (9) for sea surface wave
parameters
> Dear Andrew
>
> Thanks - this is a fruitful discussion. I think we agree on proposing these
> new names
>
> sea_surface_wave_height
Yes, but depends on the community (list) accepting the idea of having a common
concept
of 'sea_surface_wave_height' modified by the cell methods to get particular
meanings
for 4 of the 9 proposed wave parameters as follows:
CF std. name; "cell_method"; constructed meaning (name)
First 2 parameters would use new cell methods:
1) sea_surface_wave_height; "time: root_mean_square";
sea_surface_wave_height_root_mean_square
2) sea_surface_wave_height; "time:
mean_of_upper_decile";sea_surface_wave_height_mean_of_upper_decile
These 2 parameters would use existing cell methods:
3) sea_surface_wave_height; "time: mean"; sea_surface_wave_height_mean
4) sea_surface_wave_height; "time: maximum"; sea_surface_wave_height_maximum
List readers, I would appreciate any feedback on the idea of using
common concept + cell_method?
> sea_surface_wave_mean_crest_period
> sea_surface_wave_significant_wave_period
Yes, these 2 OK.
>
> You have proposed a new name
> sea_surface_wave_period_at_second_largest_peak_of_the_energy_spectrum
> (to replace an earlier proposal). Is this the "second" corresponding to this
> existing name being the "first":
> sea_surface_wave_period_at_variance_spectral_density_maximum
> and if so, could your new quantity be
> sea_surface_wave_period_at_second_largest_peak_of_variance_spectral_density
> for consistency?
Yes, I this would be more consistent.
>
> Thanks for your explanation of sea_surface_wave_zeroth_spectral_moment. That
> leads me to ask whether it could be called
> sea_surface_wave_variance_spectral_density_zeroth_frequency_moment
> to correspond to the terminology used in the existing names
>
> sea_surface_wave_mean_period_from_variance_spectral_density_first|second_frequency_moment
Yes it could be called that, again fits in with existing terminology.
>
> Finally, you have explained that
> sea_surface_wave_root_mean_square_amplitude
> is the square root of the zeroth moment. It is liable to be confused with the
> root_mean_square sea_surface_wave_height. Would it be acceptable to call it,
> rather clumsily,
>
> sea_surface_wave_amplitude_from_variance_spectral_density_zeroth_frequency_moment
> which follows the pattern of the names of wave periods calculated from
> moments?
> If it is always called sea_surface_wave_root_mean_square_amplitude and that
> doesn't cause any confusion in practice, we don't need to worry about it. But
> you did point out "not be confused with", so I suppose it might be a problem!
I think
'sea_surface_wave_amplitude_from_variance_spectral_density_zeroth_frequency_moment'
is longer/more clumsy than it needs to be. How about just
'sea_surface_wave_root_mean_square_amplitude_from_variance_spectral_density'
with a the 'description' in the CF XML stating that:
"The sea surface wave root mean square amplitude (Yrms) is derived from the wave
energy spectrum
zeroth spectral moment (M0) which is the area under the wave energy spectrum
(variance spectral density) curve. Yrms is the square root of the zeroth
spectral moment (M0) i.e Yrms=sqrt(M0)
This wave parameter is not to be confused with the root mean square wave height
which is
calculated from a zero crossing analysis of the wave height time series data
recording."
With this name and description it is not likely to be confused with
'sea_surface_wave_height' + cell method (root_mean_square).
>
> We are also going to propose two new cell_methods
>
> root_mean_square
> mean_of_upper_decile.
>
> We have to do that in the trac system but it's not a large change to the
> convention.
>
> Best wishes
>
> Jonathan
>
>
Received on Tue Oct 12 2010 - 17:59:36 BST
