Hi Jonathon and CF metadata list,
My responses are in-line below.
Andrew Walsh
----- Original Message -----
From: "Jonathan Gregory" <[email protected]>
To: "andrew walsh" <[email protected]>
Cc: "Patrick Gorringe" <[email protected]>; <[email protected]>;
"Mark Kulmar" <[email protected]>; <[email protected]>; "Roger
Proctor" <[email protected]>
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
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