# [CF-metadata] standard names for sea surface roughness variables

Saulter, Andrew andrew.saulter at metoffice.gov.uk
Fri Sep 14 06:20:57 MDT 2018

```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.

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
andrew.saulter at metoffice.gov.uk http://www.metoffice.gov.uk

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