Thanks Alison. I'm OK with the change from "average" to "mean". Regards, Elodie
On 22/06/2016 17:02, Nan Galbraith wrote: > Thanks you, Alison, Roy, Elodie and all - > Nan > > On 6/22/16 9:32 AM, [email protected] wrote: >> >> Dear Roy, Elodie, Nan, Jonathan, Chris, et al, >> >> Many thanks to Elodie for her original wave name proposals, to Roy >> for doing so much work on designing a systematic approach to CF wave >> names and to all those who have worked to improve these proposals on >> and off the list. My apologies for taking a while to respond to this >> discussion. >> >> I think it is useful to continue Roy’s approach of breaking the >> original set of proposals into three groups, so here I will address >> just the height names. I will address the other sets of proposals >> separately. >> >> I note the discussion around the use of mean, maximum and minimum in >> the standard name, rather than our more usual approach of placing >> such information in the cell_methods attribute. We do already have >> eleven existing names that refer to “wave_mean_period”. I looked back >> at the original discussion of these names in 2006 in which it was >> agreed to use “mean” in the name because wave quantities can be >> calculated in many and diverse ways from the power spectrum and it is >> not useful to come up with separate cell_methods for them all. I >> think Roy made a similar point earlier on in this discussion. In >> fact, I don’t think that putting the quantities in cell_methods would >> greatly reduce the number of new names required in this instance. >> Also, I’m strongly in favour of Roy’s approach of adopting as far as >> possible a consistent convention for all wave standard names so I >> support the use of mean, maximum and minimum in these proposals for >> consistency with the existing names. >> >> I note the general point made by Nan about the ordering of sentences >> in the definitions of new wave names >> (http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2016/058843.html). >> I’m broadly supportive of adopting this approach as we go along (so >> this doesn’t mean we need to review all existing wave name >> definitions during the current discussion). I think the definitions >> of the wave height proposals are in any case consistent with Nan’s >> approach. >> >> For the two mean_height names, I suggest a minor change in which we >> replace the word “average” in the definitions with the word “mean” >> for clarity and consistency with the names themselves, otherwise they >> look fine. These two names would therefore be as follows: >> >> sea_surface_wave_mean_height (m) >> >> ‘Wave height is defined as the vertical distance from a wave trough >> to the following wave crest. The mean wave height is the mean trough >> to crest distance measured during the observation period.’ >> >> sea_surface_wave_mean_height_of_highest_tenth (m) >> >> ‘Wave height is defined as the vertical distance from a wave trough >> to the following wave crest. The height of the highest tenth is >> defined as the mean of the highest ten per cent of trough to crest >> distances measured during the observation period.’ >> >> If Roy and Elodie are happy with this small change, then these names >> can be accepted for publication. >> >> The remaining height names look fine and are accepted for publication >> in the standard name table: >> >> sea_surface_wave_significant_height (m) (Modification to definition >> of existing name) >> >> ‘Significant wave height is a statistic computed from wave >> measurements and corresponds to the average height of the highest one >> third of the waves, where the height is defined as the vertical >> distance from a wave trough to the following wave crest.’ >> >> sea_surface_wind_wave_significant_height (m) (Modification to >> definition of existing name) >> >> ‘Wind waves are waves on the ocean surface and are the high frequency >> portion of a bimodal wave frequency spectrum. Significant wave height >> is a statistic computed from wave measurements and corresponds to the >> average height of the highest one third of the waves, where the >> height is defined as the vertical distance from a wave trough to the >> following wave crest.’ >> >> sea_surface_swell_wave_significant_height (m) (Modification to >> definition of existing name) >> >> ‘Swell waves are waves on the ocean surface and are the low frequency >> portion of a bimodal wave frequency spectrum. Significant wave height >> is a statistic computed from wave measurements and corresponds to the >> average height of the highest one third of the waves, where the >> height is defined as the vertical distance from a wave trough to the >> following wave crest.’ >> >> sea_surface_primary_swell_wave_significant_height (m) >> >> ‘Swell waves are waves on the ocean surface and are the low frequency >> portion of a bimodal wave frequency spectrum. The primary swell wave >> is the most energetic swell wave. Significant wave height is a >> statistic computed from wave measurements and corresponds to the >> average height of the highest one third of the waves, where the >> height is defined as the vertical distance from a wave trough to the >> following wave crest.’ >> >> sea_surface_secondary_swell_wave_significant_height (m) >> >> ‘Swell waves are waves on the ocean surface and are 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. Significant wave height is a >> statistic computed from wave measurements and corresponds to the >> average height of the highest one third of the waves, where the >> height is defined as the vertical distance from a wave trough to the >> following wave crest.’ >> >> sea_surface_wave_maximum_height (m) >> >> ‘Wave height is defined as the vertical distance from a wave trough >> to the following wave crest. The maximum wave height is the greatest >> trough to crest distance measured during the observation period.’ >> >> sea_surface_wave_maximum_crest_height (m) >> >> ‘The crest is the highest point of a wave. Crest height is the >> vertical distance between the crest and the calm sea surface. Maximum >> crest height is the maximum value measured during the observation >> period.’ >> >> sea_surface_wave_maximum_trough_depth (m) >> >> ‘The trough is the lowest point of a wave. Trough depth is the >> vertical distance between the trough and the calm sea surface. >> Maximum trough depth is the maximum value measured during the >> observation period.’ >> >> The current status of these names can also be viewed in the CEDA >> vocabulary editor: >> http://cfeditor.ceda.ac.uk/proposals/1?status=active&namefilter=height+trough&proposerfilter=Roy+Elodie&descfilter=&unitfilter=&yearfilter=&commentfilter=&filter+and+display=Filter >> <http://cfeditor.ceda.ac.uk/proposals/1?status=active&namefilter=height+trough&proposerfilter=Roy+Elodie&descfilter=&unitfilter=&yearfilter=&commentfilter=&filter+and+display=Filter>. >> >> >> The next update of the standard name table will take place on 19^th >> July. >> >> 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. >> >> > \ > _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
