Hello Roy and all,
I think you are right Roy, let's look at height variables first to keep
things manageable.
I'm sorry it took me a little while to reply, I wanted to first discuss
things with Marta and wave modellers from Copernicus.
We agree that the estimator should be included in a long_name, not in
the Standard Name. So the list of names we "need" for height are reduced to:
- sea_surface_wave_significant_height -> already exists
- *sea_surface_wave_maximum_height **
* - *sea_surface_wave_average_height *
We think that for the maximum_wave_height and mean_wave_height, the
statistics should be included in the Standard Name and not in the
cell_methods, because it is really part of the definition and not
something applied afterwards to the physical parameter. Am I making sense?
- *sea_surface_wave_height_of_highest_tenth*
- *sea_surface_wave_height_of_the_highest_crest*
- *sea_surface_wave_deepest_trough*
- *sea_surface_primary_swell_wave_significant_height*
- *sea_surface_secondary_swell_wave_significant_height*
- sea_surface_wind_wave_significant_height -> already exists
So we would be down to 7 new Standard Names.
Regards,
Elodie
On 02/05/2016 10:51, Lowry, Roy K. wrote:
>
>
> Dear Elodie,
>
>
> Following my comments on Hs, here are some comments on the rest of
> your proposals for additional wave height Standard Names. Most of the
> comments follow the same theme of placing statistic derivation methods
> out of the Standard Name. My proposed changes will affect your
> definitions, but let's discuss names first to keep things manageable.
>
>
> *sea_surface_wave_zero_upcrossing_average_height_of_highest_tenth*
>
> Use sea_surface_wave_average_height_of_highest_tenth as the Standard
> Name with the derivation method in the long name. If zero-upcrossing
> analysis is based on the method specified by Tucker and Draper then
> include ?Tucker-Draper? in the label.**
>
> *sea_surface_wave_zero_upcrossing_average_height*
>
> Suggest sea_surface_wave_average_height This raises the question of
> whether ?average? should be handled by a cell method? However, there
> is a precedent for the inclusion of statistics in the name already
> established for waves e.g.
> sea_surface_wave_zero_upcrossing_average_height.**
>
> *sea_surface_wave_maximum_height*
>
> OK
>
> *sea_surface_wave_zero_upcrossing_maximum_height*
>
> Use sea_surface_wave_maximum_height and Long Name for the derivation
> method.
>
> *sea_surface_wave_crest_through_maximum_height*
>
> Should ?through? be ?trough?? Also, I?m not clear on exactly what this
> is. Is it the distance from the deepest trough to the highest crest in
> the analysis (i.e. the sum of sea_surface_wave_deepest_trough and
> sea_surface_wave_height_of_the_highest_crest) or the greatest crest to
> following trough distance in the analysis. Could you clarify then I?ll
> suggest a change to the name?
>
> *sea_surface_wave_deepest_through*
>
> Assume you mean sea_surface_wave_deepest_trough, in which
> case OK.
>
> *sea_surface_wave_height_of_the_highest_crest*
>
> OK
>
> *sea_surface_primary_swell_wave_significant_height*
>
> ?Spectral? removed from your suggestion with derivation
> moved to Long Name.
>
> *sea_surface_secondary_swell_wave_significant_height*
>
> ?Spectral? removed from your suggestion with derivation
> moved to Long Name.
>
> Your other height proposal
> (sea_surface_wind_wave_spectral_significant_height) is covered by the
> pre-existing Standard Name sea_surface_wind_wave_significant_height.
>
>
> Cheers, Roy.
>
>
> Please note that I partially retired on 01/11/2015. I am now only
> working 7.5 hours a week and can only guarantee e-mail response on
> Wednesdays, my day in the office. All vocabulary queries should be
> sent to enquiries at bodc.ac.uk. Please also use this e-mail if your
> requirement is urgent.
>
>
>
> ------------------------------------------------------------------------
> *From:* CF-metadata <cf-metadata-bounces at cgd.ucar.edu> on behalf of
> Elodie Fernandez <elodie.fernandez at mercator-ocean.fr>
> *Sent:* 28 April 2016 16:18
> *To:* cf-metadata at cgd.ucar.edu
> *Cc:* mar at puertos.es
> *Subject:* [CF-metadata] Waves
>
> Hi all,
>
> So here are our proposals for wave variables that will be available
> through the European Copernicus Marine service. It's split in two
> "categories": names for the whole spectrum and names for the
> partitions. I added in copy for this topic Marta de Alfonso
> Alonso-Munoyerro who is an expert in waves from Puertos del Estado.
>
> -------------------------------------
> Whole partition
> -------------------------------------
>
> 1. Height
>
> Significant height can be measured using different methods, so we
> think that the already existing definition should be more precise and
> that new names should be added.
>
> 1.a *"sea_surface_significant_height"* (modification of definition)
> unit m
> Height is the vertical distance above the surface. Significant wave
> height can be estimated by zero upcrossing analysis and by spectral
> analysis. The generic significant wave height is used when the
> estimator is unknown.
>
> 1.b *"sea_surface_wave_spectral_significant_height"*
> unit m
> Height is the vertical distance above the surface. It can be defined
> from spectral analysis. The wave directional spectrum can be written
> as a five dimensional function S(t,x,y,f,theta) where t is time, x and
> y are horizontal coordinates (such as longitude and latitude), f is
> frequency and theta is direction. S has the standard name
> sea_surface_wave_directional_variance_spectral_density. S can be
> integrated over direction to give S1= integral(S dtheta) and this
> quantity has the standard name
> sea_surface_wave_variance_spectral_density. Frequency moments, M(n) of
> S1 can then be calculated as follows: M(n) = integral(S1 f^n df),
> where f^n is f to the power of n. Spectral significant wave height is
> defined as 4* sqrt (M(0)) = 4 * sqrt ( integral(S1 df) )
>
> 1.c *"sea_surface_wave_zero_upcrossing_significant_height"*
> unit m
> Height is the vertical distance above the surface. The significant
> wave height is defined from zero upcrossing analysis as the average
> height of the highest one third waves.
>
> 1.d. *"sea_surface_wave_zero_upcrossing_average_height_of_highest_tenth*"
> unit m
> Height is the vertical distance above the surface. The average height
> of highest tenth waves is defined from zero upcrossing analysis as the
> average height of the highest one tenth waves.
>
> 1.e *"sea_surface_wave_zero_upcrossing_average_height"*
> unit m
> Height is the vertical distance above the surface. The average height
> is defined from zero upcrossing analysis as the average of wave heights.
>
> 1.f *"sea_surface_wave_maximum_height"*
> unit m
> Height is the vertical distance above the surface. Estimated maximum
> wave height is not measured but estimated from others parameters like
> significant wave height.
>
> 1.h *"sea_surface_wave_zero_upcrossing_maximum_height"*
> unit m
> Height is the vertical distance above the surface. Maximum zero
> crossing wave height is the measured maximum height of the waves
> separated by zero upcrossing analysis.
>
> 1.i *"**sea_surface_wave_crest_through_maximum_height"*
> unit m
> Height is the vertical distance above the surface. Maximum crest
> trough wave height is the measured maximum height of the waves
> separated by crests method.
>
> 1.j *"sea_surface_wave_deepest_through*"
> unit m
> Trough is the vertical distance below 0 to the minimum in a wave.
> Depth of the deepest trough is the maximum value of wave troughs.
>
> 1.k *"sea_surface_wave_height_of_the_highest_crest"*
> unit m
> Crest is the vertical distance above 0 to the maximum in a wave.
> Height of the highest crest is the maximum value of wave crests.
>
> 2. Energy
>
> 2.a *"sea_wave_spectrum_peak_energy"*
> unit mms (meter*meter*second)
> The wave directional spectrum can be written as a five dimensional
> function S(t,x,y,f,theta) where t is time, x and y are horizontal
> coordinates (such as longitude and latitude), f is frequency and theta
> is direction. S has the standard name
> sea_surface_wave_directional_variance_spectral_density. S can be
> integrated over direction to give S1= integral(S dtheta) and this
> quantity has the standard name
> sea_surface_wave_variance_spectral_density. Wave spectrum peak energy
> is the maximum value of the variance spectral density (max(S1)).
>
> 3. Period
>
> 3.a *"sea_surface_wave_mean_period"*
> unit s
> A period is an interval of time, or the time-period of an
> oscillation. Mean or averaged wave period is the average value of the
> wave periods and can be estimated by zero upcrossing analysis and by
> spectral analysis. The generic average wave period is used when the
> estimator is unknown.
>
> 3.b *"sea_surface_wave_zero_upcrossing_significant_wave_period"*
> unit s
> A period is an interval of time, or the time-period of an oscillation.
> The significant wave period is defined from zero upcrossing analysis
> as the average period of the highest one third waves.
>
> 3.c *"sea_surface_wave_zero_upcrossing_average_one_tenth_wave_period"*
> unit s
> A period is an interval of time, or the time-period of an oscillation.
> The average period highest one tenth waves is defined from zero
> upcrossing analysis as the average period of the highest one tenth waves.
>
> 3.d*"sea_surface_wave_maximum_period"*
> unit s
> A period is an interval of time, or the time-period of an oscillation.
> The maximum wave period is defined from zero upcrossing analysis as
> the maximum period of the waves.
>
> 3.e*"sea_surface_wave_period_of_highest_wave"*
> unit s
> A period is an interval of time, or the time-period of an oscillation.
> The period of the highest wave is defined from zero upcrossing
> analysis as the period of the highest wave.
>
> 4. Direction
>
> 4.a *"sea_surface_wave_from_mean_direction"*
> unit degree
> from_direction is used in the construction X_from_direction and
> indicates the direction from which the velocity vector of X is coming.
> The mean wave direction is the average direction from which waves are
> coming.
>
> 4.b *"sea_surface_wave_from_direction_at_spectral_peak"*
> unit degree
> from_direction" is used in the construction X_from_direction and
> indicates the direction from which the velocity vector of X is coming.
> The spectral peak is the most energetic wave in the total wave
> spectrum. The wave direction at spectral peak is the direction from
> which waves are coming at the spectral peak.
>
> 5. Steepness
>
> 5.a *"sea_surface_wave_maximum_steepness"*
> unit dimensionless
> The wave steepness is defined as the ratio of the wave height divided
> by the wavelength. The maximum wave steepness is the maximum value.
>
> -------------------------------------
> Partitions
> -------------------------------------
>
> We also wish to add names for the three "main" variables defining
> waves for three partitions: the wind wave, the primary swell wave and
> the secondary swell wave. These three variables are
> - the spectral significant height (1.b of our proposal
> sea_surface_wave_spectral_significant_height)
> - the direction (4.b of our proposal
> sea_surface_wave_from_direction_at_spectral_peak)
> - the period (already existing name
> sea_surface_wave_mean_period_from_variance_spectral_density_first_frequency_moment)
>
> So we propose for all three to replace in the name "sea_surface_wave"
> with "sea_surface_wind_wave", "sea_surface_primary_swell_wave" and
> "sea_surface_secondary_swell_wave". And we believe the definitions
> should be the definitions already existing or proposed on this email,
> with the addition at the end of the definition of the partition
> itself: "The directional wave spectrum can be separated into several
> partitions: wind wave contribution (WW), primary swell (SW1)
> contribution (the most energetic swell) and secondary swell
> contribution (SW2).", with a bit more detail for the wind wave: "Wind
> waves are waves on the ocean surface generated by the local wind."
>
> For example:
> *sea_surface_secondary_swell_wave_from_direction *
> unit degree
> The directional wave spectrum can be separated into several
> partitions: wind wave contribution (WW), primary swell (SW1)
> contribution (the most energetic swell) and secondary swell
> contribution (SW2). The mean wave direction is the average direction
> from which waves are coming for the secondary swell wave partition.
>
> Regards,
> Elodie Fernandez
>
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