Dear Andrew et al. This is to summarise briefly the discussion we have had in emails not on the list. You proposed the following standard_names:
sea_surface_wave_mean_wave_height sea_surface_wave_root_mean_square_wave_height sea_surface_wave_mean_wave_height_of_highest_one_tenth sea_surface_wave_maximum_wave_height sea_surface_wave_root_mean_square_amplitude sea_surface_wave_zeroth_spectral_moment sea_surface_wave_mean_crest_period sea_surface_wave_significant_wave_period sea_surface_wave_period_at_second_peak_of_the_spectrum where the heights are in m, the moment is in m2 and the periods are in s. I agree with the proposals for new wave periods. I note that we have another such existing name viz sea_surface_wave_zero_upcrossing_period. You note that sea_surface_wave_significant_height is an existing standard_name and your proposals have this style. Roy explained that these measures of wave height are evaluated from very high-frequency sampling. I think they can be described with cell_methods of the time axis. The advantages of using cell_methods are that (a) it is consistent with CF treatment of other quantities (b) it clarifies which dimension "mean" etc applies to - time in this case, not space (c) it reduces the number of standard names required. I therefore propose we introduce a standard_name of sea_surface_wave_height, and new cell_methods of root_mean_square and mean_of_upper_decile (highest one tenth); we already have cell_methods of mean and maximum, of course. I have not understood quite what root_mean_square_amplitude means, and how it relates to the wave height distribution sampled at high frequency. I note that the significant wave height could be described by a cell_method of mean_of_upper_tercile, but I would not propose that because it's a widely used term and we have a standard_name for the corresponding period. You commented that this means splitting up the information which describes a quantity into two attributes. That's quite true, but it's exactly what we have done in other such cases. The aim of the proposed common_concepts convention, on which the discussion has not been concluded, is to provide an additional attribute to "label" such groups of metadata. But for your own use, or for a particular project, you could of course define your own additional convention, which standardises the long_name, for example, to serve this purpose. Regarding the moment, I wonder whether this is related to the moments referred to by the existing standard_names sea_surface_wave_mean_period_from_ variance_spectral_density_first|second_frequency_moment. Best wishes Jonathan _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
