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" <[email protected]> > To: "[email protected]" <[email protected]> > 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 <[email protected]> On Behalf Of Jonathan > Gregory > Sent: 05 October 2018 14:25 > To: [email protected] > 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" > <[email protected]> ----- > > > Date: Fri, 5 Oct 2018 10:40:56 +0000 > > From: "Saulter, Andrew" <[email protected]> > > To: "[email protected]" <[email protected]> > > 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_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_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 <[email protected]> On Behalf Of > > Jonathan Gregory > > Sent: 01 October 2018 18:29 > > To: [email protected] > > 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" > > <[email protected]> ----- > > > > > Date: Mon, 1 Oct 2018 09:30:03 +0000 > > > From: "Saulter, Andrew" <[email protected]> > > > To: "[email protected]" <[email protected]> > > > 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 <[email protected]> > > > Sent: 28 September 2018 13:46 > > > To: Saulter, Andrew <[email protected]> > > > Cc: [email protected] > > > 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 > > > [email protected] > > > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > > > > ----- End forwarded message ----- > > _______________________________________________ > > 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 > > ----- End forwarded message ----- > _______________________________________________ > 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 _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
