# Concept

## sea_surface_wave_mean_period_from_variance_spectral_density_first_frequency_moment

URI | http://vocab.nerc.ac.uk/collection/P07/current/CFV8N73/ | |
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Within Vocab | Climate and Forecast Standard Names | |

Alternative Labels | ||

Definition | The wave directional spectrum can be written as a five dimensional function S(t,x,y,f,theta) where t is time, x and y are horizontal coordinates (such as longitude and latitude), f is frequency and theta is direction. S has the standard name sea_surface_wave_directional_variance_spectral_density. S can be integrated over direction to give S1= integral(S dtheta) and this quantity has the standard name sea_surface_wave_variance_spectral_density. Frequency moments, M(n) of S1 can then be calculated as follows: M(n) = integral(S1 f^n df), where f^n is f to the power of n. The first wave period, T(m1) is calculated as the ratio M(0)/M(1). | |

Date | 2008-04-15T14:00: | |

Identifier | SDN:P07::CFV8N73 | |

Note | accepted | |

Has Current Version | 1 | |

version | 1 | |

iop Properties |

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