Dear Andy and Jonathan, Thank you for the proposal and discussion of these seven new names.
For the first five I have made some minor cosmetic tweaks to the definitions. I have also added a reference (originally provided by Andy) to the Charnock definition. It is fine, indeed useful, if we can point to external references where necessary in standard name definitions. charnock_coefficient_for_surface_roughness_length_for_momentum_in_air (Canonical units: 1) 'Coefficient value, based on the Charnock (1955) empirical expression for deriving the quantity with standard name surface_roughness_length_for_momentum_in_air over the ocean. Reference: AMS Glossary http://glossary.ametsoc.org/wiki/Charnock%27s_relation. The surface called "surface" means the lower boundary of the atmosphere.' sea_surface_wave_mean_square_slope (Canonical units: 1) 'Wave slope describes an aspect of sea surface wave geometry related to sea surface roughness. Mean square slope describes a derivation over multiple waves within a sea-state, for example calculated from moments of the wave directional spectrum.' sea_surface_wave_mean_square_x_slope (Canonical units: 1) 'Wave slope describes an aspect of sea surface wave geometry related to sea surface roughness. Mean square slope describes a derivation over multiple waves within a sea-state, for example calculated from moments of the wave directional spectrum. The phrase "x_slope" indicates that slope values are derived from vector components along the grid x-axis.' sea_surface_wave_mean_square_y_slope (Canonical units: 1) 'Wave slope describes an aspect of sea surface wave geometry related to sea surface roughness. Mean square slope describes a derivation over multiple waves within a sea-state, for example calculated from moments of the wave directional spectrum. The phrase "y_slope" indicates that slope values are derived from vector components along the grid y-axis.' sea_surface_mean_square_upwave_slope_direction (Canonical units: degree) 'Wave slope describes an aspect of sea surface wave geometry related to sea surface roughness. Mean square slope describes a derivation over multiple waves within a sea-state, for example calculated from moments of the wave directional spectrum. The phrase "upwave_slope_direction" is used to assign a primary directional axis along which wave energy associated with the slope calculation is travelling; "upwave" is equivalent to "from_direction" which is used in some standard names.' These names are accepted for publication in the standard name table and will be added in the 15th October update. The remaining two names are also looking good. I have added an extra sentence to the definitions to cross-reference sea_surface_mean_square_upwave_slope_direction. This is because the previous sentence discusses the 'the axis from which waves are travelling' and I think it's important to be clear that we are referring here to the upwave_slope_direction and not the existing wave_from_direction names. If you are happy with the following definitions then I think these names could also be accepted. sea_surface_mean_square_upwave_slope (Canonical units: 1) 'Wave slope describes an aspect of sea surface wave geometry related to sea surface roughness. Mean square slope describes a derivation over multiple waves within a sea-state, for example calculated from moments of the wave directional spectrum. The phrase "upwave_slope" means that slope values are derived from vector components along (parallel to) the axis from which waves are travelling. The primary directional axis along which wave energy associated with the slope calculation is travelling has the standard name sea_surface_mean_square_upwave_slope_direction.' sea_surface_mean_square_crosswave_slope (Canonical units: 1) 'Wave slope describes an aspect of sea surface wave geometry related to sea surface roughness. Mean square slope describes a derivation over multiple waves within a sea-state, for example calculated from moments of the wave directional spectrum. The phrase "crosswave_slope" means that slope values are derived from vector components across (normal to) the axis from which waves are travelling. The primary directional axis along which wave energy associated with the slope calculation is travelling has the standard name sea_surface_mean_square_upwave_slope_direction.' Best wishes, Alison ------ Alison Pamment Tel: +44 1235 778065 NCAS/Centre for Environmental Data Archival Email: alison.pamm...@stfc.ac.uk STFC Rutherford Appleton Laboratory R25, 2.22 Harwell Oxford, Didcot, OX11 0QX, U.K. -----Original Message----- From: CF-metadata <cf-metadata-boun...@cgd.ucar.edu> On Behalf Of Jonathan Gregory Sent: 05 October 2018 14:57 To: Saulter, Andrew <andrew.saul...@metoffice.gov.uk> Cc: cf-metadata@cgd.ucar.edu Subject: Re: [CF-metadata] standard names for sea surface roughness variables Dear Andy Those names look just right to me. Thanks very much. Have a good weekend downing (or upping) excellent Cornish beer. Cheers Jonathan On Fri, Oct 05, 2018 at 01:39:08PM +0000, Saulter, Andrew wrote: > Date: Fri, 5 Oct 2018 13:39:08 +0000 > From: "Saulter, Andrew" <andrew.saul...@metoffice.gov.uk> > To: "cf-metadata@cgd.ucar.edu" <cf-metadata@cgd.ucar.edu> > Subject: Re: [CF-metadata] standard names for sea surface roughness > variables > > Dear Jonathon, > > And thanks as always for your help with these. I agree re moving the > component names around. So, for completeness: > > charnock_coefficient_for_surface_roughness_length_for_momentum_in_air > Units: 1 > Coefficient value, based on the Charnock (1955) empirical expression for > deriving surface_roughness_length_for_momentum_in_air over the ocean. The > surface called "surface" means the lower boundary of the atmosphere. > > sea_surface_wave_mean_square_slope > Units: 1 > Wave slope describes an aspect of sea surface wave geometry related to sea > surface roughness. Mean square slope describes a derivation over multiple > waves within a sea-state, for example calculated from moments of the wave > directional spectrum. > > sea_surface_wave_mean_square_x_slope > Units: 1 > Wave slope describes an aspect of sea surface wave geometry related to sea > surface roughness. Mean square slope describes a derivation over multiple > waves within a sea-state, for example calculated from moments of the wave > directional spectrum. "x" indicates that slope values are derived from vector > components along the grid x-axis. > > sea_surface_wave_mean_square_y_slope > Units: 1 > Wave slope describes an aspect of sea surface wave geometry related to sea > surface roughness. Mean square slope describes a derivation over multiple > waves within a sea-state, for example calculated from moments of the wave > directional spectrum. "y" indicates that slope values are derived from vector > components along the grid y-axis. > > sea_surface_mean_square_upwave_slope_direction > Units: degree > Wave slope describes an aspect of sea surface wave geometry related to sea > surface roughness. Mean square slope describes a derivation over multiple > waves within a sea-state, for example calculated from moments of the wave > directional spectrum. "upwave_slope_direction" is used to assign a primary > directional axis along which wave energy associated with the slope > calculation is travelling; in this case "upwave" is equivalent to a > "from_direction". > > sea_surface_mean_square upwave_slope > Units: 1 > Wave slope describes an aspect of sea surface wave geometry related to sea > surface roughness. Mean square slope describes a derivation over multiple > waves within a sea-state, for example calculated from moments of the wave > directional spectrum. "upwave" indicates that slope values are derived from > vector components along (parallel to) the axis from which waves are > travelling. > > sea_surface_mean_square_crosswave_slope > Units: 1 > Wave slope describes an aspect of sea surface wave geometry related to sea > surface roughness. Mean square slope describes a derivation over multiple > waves within a sea-state, for example calculated from moments of the wave > directional spectrum. "crosswave" indicates that slope values are derived > from vector components across (normal to) the axis from which waves are > travelling. > > Have a very good weekend > Andy > > > > -----Original Message----- > From: CF-metadata <cf-metadata-boun...@cgd.ucar.edu> On Behalf Of > Jonathan Gregory > Sent: 05 October 2018 14:25 > To: cf-metadata@cgd.ucar.edu > Subject: [CF-metadata] standard names for sea surface roughness > variables > > Dear Andy > > Thanks for your persistence and patience! Yes, I think are looking sensible > now, as you say. > > > [Thinking even more long term, upwave/downwave slopes could be > > assigned different values based on wave asymmetry, but lets not go > > there yet...] > > ... but it is sufficient reason for future-proofing I think. > > I'm happy with all these except that I would suggest putting the component > immediately before "slope", which is what it most closely applies to i.e. > > > sea_surface_wave_mean_square_x_slope > > sea_surface_wave_mean_square_y_slope > > sea_surface_mean_square_upwave_slope > > sea_surface_mean_square_crosswave_slope > > This would be consistent with existing stdnames e.g. > downward_x_stress_at_sea_ice_base > land_ice_x_velocity > > Best wishes > > Jonathan > > ----- Forwarded message from "Saulter, Andrew" > <andrew.saul...@metoffice.gov.uk> ----- > > > Date: Fri, 5 Oct 2018 10:40:56 +0000 > > From: "Saulter, Andrew" <andrew.saul...@metoffice.gov.uk> > > To: "cf-metadata@cgd.ucar.edu" <cf-metadata@cgd.ucar.edu> > > Subject: Re: [CF-metadata] standard names for sea surface roughness > > variables > > > > Dear Jonathon, > > > > Thanks a lot, that is really helpful. Whilst I appreciate your point > > about whether or not '_upwave/_downwave' are necessary if MSS is > > unsigned, I think it wold still be useful to have this since the > > _mean_square_slope_*_direction may well get compared with > > _wave_*_direction and/or _wind_*_direction. Since and these latter > > follow a convention it is useful/necessary not to have any ambiguity > > in how these are referenced. [Thinking even more long term, > > upwave/downwave slopes could be assigned different values based on > > wave asymmetry, but lets not go there yet...] > > > > So, I think we have enough now to summarise the proposed new names and see > > how we are doing... > > > > Agreed so far (I think) from earlier mails: > > > > charnock_coefficient_for_surface_roughness_length_for_momentum_in_ai > > r > > Units: 1 > > Coefficient value, based on the Charnock (1955) empirical expression for > > deriving surface_roughness_length_for_momentum_in_air over the ocean. The > > surface called "surface" means the lower boundary of the atmosphere. > > > > sea_surface_wave_mean_square_slope > > Units: 1 > > Wave slope describes an aspect of sea surface wave geometry related to sea > > surface roughness. Mean square slope describes a derivation over multiple > > waves within a sea-state, for example calculated from moments of the wave > > directional spectrum. > > > > sea_surface_wave_x_mean_square_slope > > Units: 1 > > Wave slope describes an aspect of sea surface wave geometry related to sea > > surface roughness. Mean square slope describes a derivation over multiple > > waves within a sea-state, for example calculated from moments of the wave > > directional spectrum. "x" indicates that slope values are derived from > > vector components along the grid x-axis. > > > > sea_surface_wave_y_mean_square_slope > > Units: 1 > > Wave slope describes an aspect of sea surface wave geometry related to sea > > surface roughness. Mean square slope describes a derivation over multiple > > waves within a sea-state, for example calculated from moments of the wave > > directional spectrum. "y" indicates that slope values are derived from > > vector components along the grid y-axis. > > > > Testing the new 'upwave' names: > > > > sea_surface_upwave_mean_square_slope_direction > > Units: degree > > Wave slope describes an aspect of sea surface wave geometry related to sea > > surface roughness. Mean square slope describes a derivation over multiple > > waves within a sea-state, for example calculated from moments of the wave > > directional spectrum. " direction" is used to assign a directional axis > > along which wave energy is travelling, with "upwave" used to indicate that > > this is equivalent to a "from_direction". > > > > sea_surface_upwave_mean_square_slope > > Units: 1 > > Wave slope describes an aspect of sea surface wave geometry related to sea > > surface roughness. Mean square slope describes a derivation over multiple > > waves within a sea-state, for example calculated from moments of the wave > > directional spectrum. "upwave" indicates that slope values are derived from > > vector components along (parallel to) the axis from which waves are > > travelling. > > > > sea_surface_crosswave_mean_square_slope > > Units: 1 > > Wave slope describes an aspect of sea surface wave geometry related to sea > > surface roughness. Mean square slope describes a derivation over multiple > > waves within a sea-state, for example calculated from moments of the wave > > directional spectrum. "crosswave" indicates that slope values are derived > > from vector components across (normal to) the axis from which waves are > > travelling. > > > > Hope these are beginning to sound sensible :-) > > > > Cheers > > Andy > > > > > > -----Original Message----- > > From: CF-metadata <cf-metadata-boun...@cgd.ucar.edu> On Behalf Of > > Jonathan Gregory > > Sent: 01 October 2018 18:29 > > To: cf-metadata@cgd.ucar.edu > > Subject: Re: [CF-metadata] standard names for sea surface roughness > > variables > > > > Dear Andy > > > > Thanks. I think your suggestion of "upwind" is certainly clearer than "from" > > (and "downwind" would be much better than "to"). Your middle options would > > be fine. > > > > > Parallel component: > > > sea_surface_wave_mean_square_slope_along_upwave_direction > > > Normal component: > > > sea_surface_wave_mean_square_slope_across_upwave_direction > > > > and your first options would be OK too, except I wonder if they'd be > > better as > > > > > Parallel component: sea_surface_mean_square_upwave_slope > > > Normal component: sea_surface_mean_square_crosswave_slope > > > > since it's the slope which is along or across the direction, and I made > > crosswave into one word like upwave, upward, eastward, etc. I think I'd > > prefer these shorter ones myself. > > > > But I still have a question about whether upwave and downwave need to be > > distinguished anyway for a mean square slope. Isn't avg((dh/dx)^2) the same > > regardless of the sign convention of x, if x is the wave direction? If it's > > not, don't you have to say whether cross-wave is leftward or rightward, > > correspondingly? > > > > Best wishes > > > > Jonathan > > > > > > ----- Forwarded message from "Saulter, Andrew" > > <andrew.saul...@metoffice.gov.uk> ----- > > > > > Date: Mon, 1 Oct 2018 09:30:03 +0000 > > > From: "Saulter, Andrew" <andrew.saul...@metoffice.gov.uk> > > > To: "cf-metadata@cgd.ucar.edu" <cf-metadata@cgd.ucar.edu> > > > Subject: Re: [CF-metadata] standard names for sea surface > > > roughness variables > > > > > > Good morning Jonathon, > > > > > > Was nice to have a weekend's reflection on this, not least because I also > > > got a bit more feedback from some of my other waves colleagues (thanks > > > Fabrice). > > > > > > A quick fundamental, the reason we need to have some form of 'along' and > > > 'across' follows the same argument as the 'spread' conversation. > > > Basically, wave energy in a given sea-state is not uni-directional, so we > > > have a dominant/mean direction that gets calculated, but there will be a > > > component of wave energy (with associated height, period, slope > > > characteristics etc.) that runs normal to this. > > > > > > In terms of what the "direction" really is, the suggestion I've been > > > given is "upwave", i.e. a wave equivalent of "upwind" and, therefore, > > > same as "wave_from_direction" (correcting my initial suggestion of "to" > > > in the previous post). > > > > > > This gives us a few choices for names I think? > > > > > > Least verbose: > > > Direction: sea_surface_upwave_mean_square_slope_direction / > > > sea_surface_wave_mean_square_slope_from_direction* > > > Parallel component: sea_surface_upwave_mean_square_slope > > > Normal component: sea_surface_cross_wave_mean_square_slope > > > > > > More verbose (but perhaps more clear?): > > > Direction: sea_surface_upwave_mean_square_slope_direction / > > > sea_surface_wave_mean_square_slope_from_direction* > > > Parallel component: > > > sea_surface_wave_mean_square_slope_along_upwave_direction > > > Normal component: > > > sea_surface_wave_mean_square_slope_across_upwave_direction > > > > > > More consistent with existing names (but possibly least clear?): > > > Direction: sea_surface_wave_mean_square_slope_from_direction > > > Parallel component: > > > sea_surface_wave_mean_square_slope_along_from_direction > > > Normal component: > > > sea_surface_wave_mean_square_slope_across_from_direction > > > > > > * if we use _from_direction in conjunction with _upwave, then we need to > > > add some text to link the two terms in the standard name definition. > > > > > > Any of these make sense? > > > Cheers > > > Andy > > > > > > PS. Devon is geographically 'up' from Cornwall - but definitely 'down' in > > > terms of the quality of pasties, clotted cream and beer.... > > > > > > > > > > > > -----Original Message----- > > > From: Jonathan Gregory <j.m.greg...@reading.ac.uk> > > > Sent: 28 September 2018 13:46 > > > To: Saulter, Andrew <andrew.saul...@metoffice.gov.uk> > > > Cc: cf-metadata@cgd.ucar.edu > > > Subject: Re: [CF-metadata] standard names for sea surface > > > roughness variables > > > > > > Dear Andy > > > > > > > Re the direction of the _mean_square_slope, the parameter and > > > > calculation method from the wave spectrum is sufficiently different > > > > from that for _wave_[to/from]_direction that it should stand alone. > > > > There has already been a precedent set for this with waves, where > > > > different forms of parameter calculation from the spectrum are given > > > > their own names because there is not only a calculation difference but > > > > a different physical interpretation of each parameter (e.g. the various > > > > type of wave period). > > > > > > OK, fair enough. So you need > > > sea_surface_wave_mean_square_slope_to_direction. > > > > > > I'm still stuck with what this "direction" really is. Can we insert > > > anything else for ? in > > > sea_surface_wave_mean_square_slope_along_?_direction > > > sea_surface_wave_mean_square_slope_across_?_direction > > > Apparently you want to quantify the mean square slope along and across > > > the direction of the mean square slope. Is that right? I'm not sure what > > > it means. > > > Without the "mean square", I'd think that the slope normal to the > > > direction of the slope must be zero, but it must be more subtle than that > > > in this case! > > > > > > Is there really an ambiguity of to/from with a mean square slope? It > > > seems to me that it must be the same (unsigned) number regardless of > > > whether you go backwards or forwards on a particular direction. > > > > > > Is Devon up or down from Cornwall? > > > > > > Best wishes > > > > > > Jonathan > > > > > > _______________________________________________ > > > CF-metadata mailing list > > > CF-metadata@cgd.ucar.edu > > > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > > > > ----- End forwarded message ----- > > _______________________________________________ > > CF-metadata mailing list > > CF-metadata@cgd.ucar.edu > > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > > > > _______________________________________________ > > CF-metadata mailing list > > CF-metadata@cgd.ucar.edu > > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > > ----- End forwarded message ----- > _______________________________________________ > CF-metadata mailing list > CF-metadata@cgd.ucar.edu > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > > _______________________________________________ > CF-metadata mailing list > CF-metadata@cgd.ucar.edu > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata _______________________________________________ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata _______________________________________________ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
