Dear Roy That's fine - thanks. I had overlooked that it was already defined.
Best wishes Jonathan ----- Forwarded message from "Lowry, Roy K." <[email protected]> ----- > Date: Fri, 28 Sep 2018 14:05:06 +0000 > From: "Lowry, Roy K." <[email protected]> > To: Jonathan Gregory <[email protected]>, Rob Thomas > <[email protected]> > CC: "[email protected]" <[email protected]> > Subject: Re: [CF-metadata] Spectral wave direction spread parameter > > Dear Jonathan, > > > I seem to remember the 'what is spread' discussion coming up last time we > encountered wave directional spread Standard Names. The Standard Name > sea_surface_wave_directional_spread has the definition: > > > Directional spread is the (one-sided) directional width within a given > sub-domain of the wave directional spectrum, 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. For a given mean wave (beam) direction > the quantity approximates half the root mean square width about the beam > axis, as derived either directly from circular moments or via the Fourier > components of the wave directional spectrum. > > > This seems to have been omitted from Rob's definition, which should I think > read: > > > The quantity with the Standard Name > sea_surface_wave_directional_spread_at_variance_spectral_density_maximum is > the directional spread of the most energetic waves. Directional spread is the > (one-sided) directional width within a given sub-domain of the wave > directional spectrum, 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. For a given mean wave (beam) direction the quantity > approximates half the root mean square width about the beam axis, as derived > either directly from circular moments or via the Fourier components of the > wave directional spectrum. > > > Cheers, Roy. > > > I have now retired but will continue to be active through an Emeritus > Fellowship using this e-mail address. > > > ________________________________ > From: CF-metadata <[email protected]> on behalf of Jonathan > Gregory <[email protected]> > Sent: 28 September 2018 13:26 > To: Rob Thomas > Cc: [email protected] > Subject: Re: [CF-metadata] Spectral wave direction spread parameter > > Dear Rob > > From the responses it's clear we need a name for this. I'm a bit nervous about > "spread", which sounds vague to me. Can you clarify it? > > Best wishes and thanks > > Jonathan > > On Fri, Sep 28, 2018 at 07:47:51AM +0000, Rob Thomas wrote: > > Date: Fri, 28 Sep 2018 07:47:51 +0000 > > From: Rob Thomas <[email protected]> > > To: "[email protected]" <[email protected]> > > Subject: [CF-metadata] Spectral wave direction spread parameter > > > > Hi, > > > > > > > > Please can I propose/request a new standard name for the list: > > "sea_surface_wave_directional_spread_at_variance_spectral_density_maximum" > > > > > > > > The rationale for this request is that in assessing our mappings of > > spectral wave parameters to the CF standard names we have mapped "Peak > > Direction" (described as "Dirp Direction for waves at peak of wave energy > > spectrum from which the waves are coming") to > > "sea_surface_wave_from_direction_at_variance_spectral_density_maximum" with > > definition: > > > > > > The quantity with standard name > > sea_surface_wave_from_direction_at_variance_spectral_density_maximum is the > > direction from which the most energetic waves are coming. The spectral peak > > is the most energetic wave in the total wave spectrum. The phrase > > "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 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. > > > > > > > > It does not appear there is an appropriate partner term for Peak Spread > > (described as "Dsprp Directional spread of waves at peak of wave energy > > spectrum") because the options currently available do not appear to tie in > > to the peak wave energy spectrum/spectral peak information. > > > > > > > > Kind regards, > > > > Rob > > > > > > > > Dr. Rob Thomas > > > > Senior Data Analyst - European Data Management Projects Team Leader > > > > > > > > Marine Institute, Rinville, Oranmore, County Galway, H91 R673, Ireland > > > > Tel: (+)353 (0)91 387 409 > > > > Mob: (+)353 (0)87 952 3467 > > > > Email: [email protected]<mailto:[email protected]> > > > > ORCID: 0000-0001-6068-4924 > > > > Web: http://data.marine.ie/ > data.marine.ie - Marine Environment<http://data.marine.ie/> > data.marine.ie > Marine Environment The investigation of Marine environments, Open Ocean, > deep-sea, estuarine, coastal and near-shore zones and mans’ impact on these > areas. > > > > > > _______________________________________________ > > CF-metadata mailing list > > [email protected] > > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > > _______________________________________________ > CF-metadata mailing list > [email protected] > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > ________________________________ > 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. > ________________________________ ----- End forwarded message ----- _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
