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 [email protected]_ <mailto:[email protected]>. Please
also use this e-mail if your requirement is urgent.
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