Hi all,
Thanks for your feedback Roy.
Here are the definitions we suggest for the 7 new parameters. They are
the usual definitions in the observations world.
- *sea_surface_wave_significant_height*
The already existing definition is "Height is the vertical distance
above the surface." We believe that this definition defines the
"sea_surface_wave_height" part, but not the "significant" part. Could it
be possible to revise it to make it more precise? We think that a more
precise definition could be :"Height is the vertical distance above the
surface. The significant height is defined as the average height of the
highest third of observed sea surface waves over a 30 minutes period."
- *sea_surface_wave_maximum_height **
*Height is the vertical distance above the surface. The maximum height
is defined as the height of the highest sea surface wave observed over a
30 minutes period.
*
*- *sea_surface_wave_average_height *
Height is the vertical distance above the surface. The average height is
defined as the average height of the sea surface waves observed over a
30 minutes period.
- *sea_surface_wave_height_of_highest_tenth*
Height is the vertical distance above the surface. The height of the
highest tenth is defined as the average height of the highest tenth of
observed sea surface waves over a 30 minutes period.
- *sea_surface_wave_height_of_the_highest_crest*
The crest is the vertical distance above the mean sea surface to the
maximum in a wave. Height of the highest crest is the maximum value of
wave crests observed over a 30 minutes period.
- *sea_surface_wave_deepest_trough*
Trough is the vertical distance below the mean sea surface to the
minimum in a wave. The deepest trough is the maximum value of wave
troughs observed over a 30 minutes period.
- *sea_surface_primary_swell_wave_significant_height*
definition of "sea_surface_wave_significant_height" + The primary swell
wave is the most energetic swell wave.
- *sea_surface_secondary_swell_significant_height*
definition of "sea_surface_wave_significant_height" + The secondary
swell wave is the second most energetic swell wave.
Regards,
Elodie
On 03/05/2016 11:00, Lowry, Roy K. wrote:
>
> Dear Elodie,
>
>
> Many thanks. I totally agree with your revised proposal for seven new
> Standard Names. I also congratulate you for the clarity of your proposals.
>
>
> The next stage would be for you to provide revised definitions for
> these seven. I will also do my best to provide my comments to you for
> your energy, steepness and period proposals by the end of the week.
>
>
> 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:* 03 May 2016 08:56
> *To:* cf-metadata at cgd.ucar.edu
> *Cc:* mar at puertos.es
> *Subject:* Re: [CF-metadata] Waves
>
> 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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