Thanks, Roy, for all your work on this. I have a possibly belated
suggestion,
and one question.
I'd like to suggest that, where we have a definition of the 'main term'
such as
'sea_surface_swell_wave', we just change the order of the sentences in the
definition, with the main term being defined first, which would give us,
for
example,
*sea_surface_swell_wave_from_direction **
**Swell waves are the low frequency portion of a bimodal wave frequency
distribution. **
**"From_direction" is used in the construction X_from_direction and
indicates the direction **
**from which the velocity vector of X is coming. The direction is a
bearing in the usual **
**geographical sense, measured positive clockwise from due north.*
I tried to write this out for each of the definitions below, but the
email message's
formatting got the better of me, and I gave up.
My question is: are we using the term 'sea_surface' in a slightly
different way from other
places it appears in CF, like sea_surface_temperature? That seems to be
a deprecated
alias for skin temperature, and should not have a depth associated with
it. Do we need
to include a description of how this term is used in waves, as part of
these definitions?
Thanks!
Nan
On 6/1/16 9:06 AM, Lowry, Roy K. wrote:
> Dear All,
> Please find the third part of the wave Standard Name proposal. This
> includes changes to the definition for five of the six existing wave
> direction Standard names plus five new Standard names.
> Based on the proposal of Elodie and Marta with further off-list
> discussion by Chris Barker, nan Galbraith and myself.
> Cheers, Roy.
> *Changes to Existing Standard Name Definitions*
>
> 1. *sea_surface_swell_wave_from_direction *
>
> */Current Definition/*
> Swell waves are waves on the ocean surface. "from_direction" is used
> in the construction X_from_direction and indicates the direction from
> which the velocity vector of X is coming.
> */New Definition/*
> "From_direction" is used in the construction X_from_direction and
> indicates the direction from which the velocity vector of X is coming.
> The direction is a bearing in the usual geographical sense, measured
> positive clockwise from due north. Swell waves are the low frequency
> portion of a bimodal wave frequency distribution.
>
> 2. *sea_surface_swell_wave_to_direction*
>
> */Current Definition /*
> Swell waves are waves on the ocean surface. "to_direction" is used in
> the construction X_to_direction and indicates the direction towards
> which the velocity vector of X is headed. The direction is a bearing
> in the usual geographical sense, measured positive clockwise from due
> north.
> */New Definition/*
> "To_direction" is used in the construction X_to_direction and
> indicates the direction towards which the velocity vector of X is
> headed. The direction is a bearing in the usual geographical sense,
> measured positive clockwise from due north. Swell waves are the low
> frequency portion of a bimodal wave frequency distribution.
>
> 3. *sea_surface_wave_from_direction*
>
> */Current Definition /*
> 'from_direction' is used in the construction X_from_direction and
> indicates the direction from which the velocity vector of X is coming.
> */New Definition/*
> "From_direction" is used in the construction X_from_direction and
> indicates the direction from which the velocity vector of X is coming.
> The direction is a bearing in the usual geographical sense, measured
> positive clockwise from due north.
>
> 4. *sea_surface_wave_to_direction *
>
> */Current Definition - No Change Proposed /*
> "to_direction" is used in the construction X_to_direction and
> indicates the direction towards which the velocity vector of X is
> headed. The direction is a bearing in the usual geographical sense,
> measured positive clockwise from due north.
>
> 5. *sea_surface_wind_wave_from_direction *
>
> */Current Definition /*
> Wind waves are waves on the ocean surface. Wind is defined as a
> two-dimensional (horizontal) air velocity vector, with no vertical
> component. (Vertical motion in the atmosphere has the standard name
> "upward_air_velocity".) "from_direction" is used in the construction
> X_from_direction and indicates the direction from which the velocity
> vector of X is coming.
> */New Definition/*
> "From_direction" is used in the construction X_from_direction and
> indicates the direction from which the velocity vector of X is coming.
> The direction is a bearing in the usual geographical sense, measured
> positive clockwise from due north. Wind waves are the high frequency
> portion of a bimodal wave frequency distribution.
>
> 6. *sea_surface_wind_wave_to_direction *
>
> */Current Definition /*
> Wind waves are waves on the ocean surface. Wind is defined as a
> two-dimensional (horizontal) air velocity vector, with no vertical
> component. (Vertical motion in the atmosphere has the standard name
> "upward_air_velocity".) "to_direction" is used in the construction
> X_to_direction and indicates the direction towards which the velocity
> vector of X is headed. The direction is a bearing in the usual
> geographical sense, measured positive clockwise from due north.
> */New Definition/*
> "To_direction" is used in the construction X_to_direction and
> indicates the direction towards which the velocity vector of X is
> headed. The direction is a bearing in the usual geographical sense,
> measured positive clockwise from due north. Wind waves are the high
> frequency portion of a bimodal wave frequency distribution.
> *New Standard Names*
>
> 1. *sea_surface_wave_from_direction_at_spectral_peak*
>
> The direction from which the waves at the spectral peak are coming.
> The spectral peak comprises the most energetic waves encountered
> during the measurement period. The direction is a bearing in the usual
> geographical sense, measured positive clockwise from due north.
> Canonical units = degrees.
> **
>
> 2. *sea_surface_primary_swell_wave_from_direction*
>
> "From_direction" is used in the construction X_from_direction and
> indicates the direction from which the velocity vector of X is coming.
> The direction is a bearing in the usual geographical sense, measured
> positive clockwise from due north. The primary swell wave is the most
> energetic wave in the low frequency portion of a bimodal wave
> frequency distribution.
> Canonical units = degrees.
>
> 3. *sea_surface_secondary_swell_wave_from_direction*
>
> "From_direction" is used in the construction X_from_direction and
> indicates the direction from which the velocity vector of X is coming.
> The direction is a bearing in the usual geographical sense, measured
> positive clockwise from due north. The secondary swell wave is the
> second most energetic wave in the low frequency portion of a bimodal
> wave frequency distribution.
> Canonical units = degrees.
>
> 4. *sea_surface_wave_maximum_steepness*
>
> Wave steepness is defined as the ratio of the wave height divided by
> the wavelength. The maximum wave steepness is the greatest value
> observed during the observation period. Wave height is defined as the
> vertical distance from a wave trough to the following wave crest. The
> wavelength is the horizontal distance from this trough to the next
> trough.
>
> Canonical units = dimensionless.
>
> 5. *sea_wave_spectrum_peak_energy*
>
> 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)).
> Canonical units = Square metre seconds (m^2.s)
> 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_ <mailto:enquiries at bodc.ac.uk>. Please
> also use this e-mail if your requirement is urgent.
> _________________________________ _
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Received on Tue Jun 14 2016 - 09:26:29 BST
