Dear Jonathon Thanks a lot for the response.
Glad you are happy with the Charnock Re the _mean_square_slope, I was probably over-thinking it. I'd also be happy to lose the magnitude part; i.e. sea_surface_wave_[xy]_mean_square_slope One further query, before I over-think something else! I've been speaking to my colleague Fabrice Ardhuin, who is significantly more expert in these parameters than I am. Fabrice highlighted that in addition to the grid x-y reference frame, it a number of users would wish to consider mean_square_slope in an along-across axis reference frame, where the axis used is a variable in its own right (e.g. a dominant slope direction derived from the wave spectrum, or estimated from wind direction). My suspicion is that x-y really implies 'grid' and not 'along-across', so that we would then need to additionally specify something like: Along: sea_surface_wave_mean_square_slope_parallel_to_dominant_direction Across: sea_surface_wave_mean_square_slope_normal_to_dominant_direction Directional variable: sea_surface_wave_mean_square_slope_dominant_to_direction But perhaps not, and a broader interpretation of x-y can be made that allows and interpretation of parallel-normal?? What do you reckon? Cheers Andy -----Original Message----- From: CF-metadata <[email protected]> On Behalf Of Jonathan Gregory Sent: 19 September 2018 15:50 To: [email protected] Subject: [CF-metadata] standard names for sea surface roughness variables Dear Andy Thanks for these proposals. > charnock_coefficient_for_surface_roughness_length_for_momentum_in_air > sea_surface_wave_mean_square_slope are consistent with existing names and look fine to me. I don't quite understand these ones. > magnitude_of_sea_surface_wave_[xy]_mean_square_slope You are considering the slopes in the x- and y-directions separately i.e. deta/dx and deta/y, where eta is sea surface height. Maybe _[xy]_slope would be clearer, if that's right. If it's a mean square, it surely must be positive, mustn't it? If so, I don't see why it needs magnitude_of. Best wishes Jonathan ----- Forwarded message from "Saulter, Andrew" <[email protected]> ----- > Date: Fri, 14 Sep 2018 12:20:57 +0000 > From: "Saulter, Andrew" <[email protected]> > To: "[email protected]" <[email protected]> > Subject: [CF-metadata] standard names for sea surface roughness > variables > > Hello everyone, hope you are all well. > > I'd like to propose some new standard names for variables relating to sea > surface roughness please. The v0 suggestions are: > > 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. > > [Not for description text, but see also > http://glossary.ametsoc.org/wiki/Charnock%27s_relation] > > > 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. > > magnitude_of_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. Magnitude of "x" indicates that slope values are > derived from vector components along the grid x-axis, with slope always > taking a positive value. > > magnitude_of_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. Magnitude of "y" indicates that slope values are > derived from vector components along the grid y-axis, with slope always > taking a positive value. > > [My main concern with these latter variables, is the use of magnitude > and vector x/y descriptors. Hopefully the descriptive text explains > this OK; basically a negative slope makes no sense in the context in > which the data are derived and used, i.e. for surface roughness > estimation] > > Will look forward to the comments :) > Cheers > Andy > > > Andy Saulter > Surge, Waves and Metocean Projects Manager Met Office FitzRoy Road > Exeter Devon EX1 3PB > Tel: +44 (0)1392 884703 Fax: +44 (0)1392 885681 > [email protected] http://www.metoffice.gov.uk > > > _______________________________________________ > 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
