average_absolute_wave_period (s) = Average absolute wave period = sea_surface_wave_mean_period_from_variance_spectral_density_first_frequency_moment
average_wave_direction (degree) = Average wave direction = sea_surface_wave_from_direction
direction_of_the_peak_of_the_spectrum (degree) = Direction of the peak of the spectrum = sea_surface_wave_from_direction_at_variance_spectral_density_maximum
relative_peak_period (s) = Relative peak period = relative peak period