Dear Roy, Thank you for getting back to me about the two sets of wave names. I'm pleased to hear they look okay! I will wait a few days to see if anyone wishes to comment further, but unless I receive any objections during the next week my intention is to accept all the remaining wave names and include them in the next update.
Improved definitions (provided they are corrections/clarifications and don't change the intended meaning of the names) are always welcome. Thank you to you and all those who have contributed so far to improving and standardising the wave names. Best wishes, Alison ------ Alison Pamment Tel: +44 1235 778065 Centre for Environmental Data Analysis Email: [email protected]<mailto:[email protected]> STFC Rutherford Appleton Laboratory R25, 2.22 Harwell Campus, Didcot, OX11 0QX, U.K. From: Lowry, Roy K. [mailto:[email protected]] Sent: 12 March 2017 15:38 To: Pamment, Alison (STFC,RAL,RALSP); [email protected]; [email protected]; [email protected] Cc: [email protected] Subject: Re: Wave periods sub-proposal Dear Alison, I've now looked at your suggestions for this sub-proposal and find them all acceptable. There is an action on me to consult with wave experts to see if improved definitions for the wave types (e.g. wind and swell) can be prepared once the work on Elodie's proposals is complete. 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 [email protected]<mailto:[email protected]>. Please also use this e-mail if your requirement is urgent. ________________________________ From: [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> Sent: 11 March 2017 12:49 To: Lowry, Roy K.; [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]> Cc: [email protected]<mailto:[email protected]> Subject: RE: Wave periods sub-proposal Dear Roy, Elodie, Stephane, et al, My detailed comments on the wave period sub-proposal names are given below. I have accepted the three proposals for new aliases with very minor tweaks to the definitions. I have also accepted several of the proposed new names. Please could you check the definitions of the last two new names - if you are happy with them then these names can also be accepted. As with the wave direction, energy and steepness names any changes agreed by 20th March will be included in the next standard name table update. A summary of all the wave names currently accepted (and not yet published) or still under discussion can be found at: http://cfeditor.ceda.ac.uk/proposals/1?status=active&namefilter=&proposerfilter=elodie&descfilter=&unitfilter=&yearfilter=&commentfilter=&filter+and+display=Filter. --- > All wave periods have Canonical Units of seconds. > > > Existing Standard Name Changes > > Justification for change: > > The classical Tucker-Draper analysis specifies multiple wave period > statistics such as zero-upcrossing period (Tz) and crest period (Tc) and the > protocols used could cause > these to differ. However, wave theory states that period of a waveform should > be uniform for all reference points on the waveform and so the possibility of > variation > should be considered an artefact and the geophysical variable should simply > be wave period. The long name can be used if required to specify the waveform > reference > and measurement protocol used, as proposed for wave height Standard Names. > > 1. sea_surface_wave_zero_upcrossing_period > A period is an interval of time, or the time-period of an oscillation. The > zero upcrossing period is defined as the time interval between consecutive > occasions on which the > surface height passes upward above the mean level. > > Replace this by: > sea_surface_wave_mean_period > A period is an interval of time, or the time-period of an oscillation. Wave > period is the interval of time between repeated features on the waveform such > as crests, troughs > or upward passes through the mean level. Wave mean period is the average > period measured over the observation duration. This proposed alias looks fine and, as with the existing wave height names, I think it is a sensible approach to use the long name to indicate the precise method by which the data values were obtained. The proposed definition seems general enough to cover all eventualities. In the last sentence "average period" should say "mean period" (consistent with the wave height names). This alias is accepted for inclusion in the standard name table. > 2. sea_surface_wind_wave_zero_upcrossing_period > A period is an interval of time, or the time-period of an oscillation. The > zero upcrossing period is defined as the time interval between consecutive > occasions on which the > surface height passes upward above the mean level. 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.) > > Replace this by: > sea_surface_wind_wave_mean_period > A period is an interval of time, or the time-period of an oscillation. Wave > period is the interval of time between repeated features on the waveform such > as crests, troughs > or upward passes through the mean level. Wave mean period is the average > period measured over the observation duration. Wind waves are the high > frequency portion > of a bimodal wave frequency distribution. As with proposal 1, in the penultimate sentence of the definition "average period" should be replaced by "mean period" (consistent with the wave height names). Otherwise this looks fine. This alias is accepted for inclusion in the standard name table. > 3. sea_surface_swell_wave_zero_upcrossing_period > A period is an interval of time, or the time-period of an oscillation. The > zero upcrossing period is defined as the time interval between consecutive > occasions on which the > surface height passes upward above the mean level. Swell waves are waves on > the ocean surface. > > Replace this by: > sea_surface_swell_wave_mean_period > A period is an interval of time, or the time-period of an oscillation. Wave > period is the interval of time between repeated features on the waveform such > as crests, troughs > or upward passes through the mean level. Wave mean period is the average > period measured over the observation duration. Swell waves are the low > frequency portion > of a bimodal wave frequency distribution. As with proposal 1, in the penultimate sentence of the definition "average period" should be replaced by "mean period" (consistent with the wave height names). Otherwise this looks fine. This alias is accepted for inclusion in the standard name table. --- > Additional Standard Names for Copernicus Proposal > > 1. sea_surface_wave_significant_period > A period is an interval of time, or the time-period of an oscillation. Wave > period is the interval of time between repeated features on the waveform such > as crests, troughs > or upward passes through the mean level. Significant wave period is a > statistic computed from wave measurements and corresponds to the average wave > period of the > highest one third of the waves. Units of s is fine and the proposed name is consistent with the existing name sea_surface_wave_significant_height. For consistency with the accepted aliases and existing wave height names "average period" in the definition should be replaced by "mean period". Taking account of Nan's suggestion to change the order of the sentences in the definition we would then have: 'Significant wave period is a statistic computed from wave measurements and corresponds to the mean wave period of the highest one third of the waves. A period is an interval of time, or the time-period of an oscillation. Wave period is the interval of time between repeated features on the waveform such as crests, troughs or upward passes through the mean level.' With these cosmetic changes this new name is accepted for publication in the standard name table. > 2. sea_surface_wave_mean_period_of_highest_tenth > A period is an interval of time, or the time-period of an oscillation. Wave > period is the interval of time between repeated features on the waveform such > as crests, troughs > or upward passes through the mean level. Wave mean period is the average > period measured over the observation duration. Mean period of the highest > tenth is the > average period of the highest one-tenth of the waves during the observation > duration. Units of s is fine. The proposed name and definition are consistent with the existing name sea_surface_wave_mean_height_of_highest_tenth. Again, replacing "average period" with "mean period" and changing the order of sentences in the definition we would have: 'Wave mean period is the mean period measured over the observation duration. Mean period of the highest tenth is the mean period of the highest one-tenth of the waves during the observation duration. A period is an interval of time, or the time-period of an oscillation. Wave period is the interval of time between repeated features on the waveform such as crests, troughs or upward passes through the mean level.' With these cosmetic changes this new name is accepted for publication in the standard name table. > 3. sea_surface_wave_maximum_period > A period is an interval of time, or the time-period of an oscillation. Wave > period is the interval of time between repeated features on the waveform such > as crests, troughs > or upward passes through the mean level. The maximum period is the longest > wave period measured during the observation period. Units of s is fine. The proposal is consistent with existing wave maximum height/depth names. Changing the order of the sentences in the definition as suggested by Nan we would have: 'The maximum wave period is the longest wave period measured during the observation period. A period is an interval of time, or the time-period of an oscillation. Wave period is the interval of time between repeated features on the waveform such as crests, troughs or upward passes through the mean level.' With this cosmetic change this new name is accepted for publication in the standard name table. > 4. sea_surface_wave_period_of_highest_wave > A period is an interval of time, or the time-period of an oscillation. Wave > period is the interval of time between repeated features on the waveform such > as crests, troughs > or upward passes through the mean level. Wave period of the highest wave is > the period determined from wave crests corresponding to the greatest vertical > distance > above mean level during the observation period. Units of s is fine. The name itself looks fine. Changing the order of the sentences in the definition as suggested by Nan we would have: 'Wave period of the highest wave is the period determined from wave crests corresponding to the greatest vertical distance above mean level during the observation period. A period is an interval of time, or the time-period of an oscillation. Wave period is the interval of time between repeated features on the waveform such as crests, troughs or upward passes through the mean level.' With this cosmetic change this new name is accepted for publication in the standard name table. > 5. sea_surface_primary_swell_wave_mean_period > A period is an interval of time, or the time-period of an oscillation. Wave > period is the interval of time between repeated features on the waveform such > as crests, troughs > or upward passes through the mean level. Wave mean period is the average > period measured over the observation duration. The primary swell wave is > the most > energetic wave in the low frequency portion of a bimodal wave frequency > distribution. Units of s is fine. The proposed name is consistent with the syntax of existing names and proposed wave direction names. Changing the order of the sentences in the definition as suggested by Nan, replacing "average period" with "mean period", and making the wording consistent with the proposed name sea_surface_primary_swell_wave_from_direction, the definition can be written as follows: 'The quantity with standard name sea_surface_primary_swell_wave_mean_period is the mean period of the most energetic swell waves. Swell waves are waves on the ocean surface and are in the low frequency portion of a bimodal wave frequency spectrum. The primary swell wave is the most energetic swell wave. A period is an interval of time, or the time-period of an oscillation. Wave period is the interval of time between repeated features on the waveform such as crests, troughs or upward passes through the mean level. Wave mean period is the average period measured over the observation duration. OK? > 6. sea_surface_secondary_swell_wave_mean_period > A period is an interval of time, or the time-period of an oscillation. Wave > period is the interval of time between repeated features on the waveform such > as crests, troughs > or upward passes through the mean level. Wave mean period is the average > period measured over the observation duration. The secondary swell wave is > the second > most energetic wave in the low frequency portion of a bimodal wave frequency > distribution. Units of s is fine. The proposed name is consistent with the syntax of existing names and proposed wave direction names. Changing the order of the sentences in the definition as suggested by Nan, replacing "average period" with "mean period", and making the wording consistent with the proposed name sea_surface_secondary_swell_wave_from_direction, the definition can be written as follows: 'The quantity with standard name sea_surface_secondary_swell_wave_mean_period is the mean period of the second most energetic swell waves. Swell waves are waves on the ocean surface and are in the low frequency portion of a bimodal wave frequency spectrum. The secondary swell wave is the second most energetic wave in the low frequency portion of a bimodal wave frequency spectrum. A period is an interval of time, or the time-period of an oscillation. Wave period is the interval of time between repeated features on the waveform such as crests, troughs or upward passes through the mean level. Wave mean period is the average period measured over the observation duration.' OK? --- Best wishes, Alison ------ Alison Pamment Tel: +44 1235 778065 Centre for Environmental Data Analysis Email: [email protected]<mailto:[email protected]> STFC Rutherford Appleton Laboratory R25, 2.22 Harwell Campus, Didcot, OX11 0QX, U.K. ________________________________ This message (and any attachments) is for the recipient only. NERC is subject to the Freedom of Information Act 2000 and the contents of this email and any reply you make may be disclosed by NERC unless it is exempt from release under the Act. Any material supplied to NERC may be stored in an electronic records management system. ________________________________
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