# Concept

## sea_surface_wind_wave_mean_period_from_variance_spectral_density_second_frequency_moment

URI | http://vocab.nerc.ac.uk/collection/P07/current/CFV8N78/ | ||
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Within Vocab | Climate and Forecast Standard Names | ||

Alternative Labels | |||

Definition | The wind 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 can be integrated over direction, thus S1= integral(S dtheta). 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 second wave period, T(m2), is calculated as the square root of the ratio M(0)/M(2). | ||

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

Identifier | SDN:P07::CFV8N78 | ||

Note | accepted | ||

Has Current Version | 1 | ||

version | 1 | ||

Same As | MMI | http://mmisw.org/ont/cf/parameter/sea_surface_wind_wave_mean_period_from_variance_spectral_density_second_frequency_moment | Mapping: 266372 |

CF | http://vocab.nerc.ac.uk/standard_name/sea_surface_wind_wave_mean_period_from_variance_spectral_density_second_frequency_moment/ | Mapping: 354908 | |

Broader | `P02:WVST` |
Wave height and period statistics | Mapping: 152131 |

P04 Global Change Master Directory Science Keywords V5 - (2) | |||

P64 Global Change Master Directory Science Keywords V6 - (2) | |||

Related | `P06:UTBB` |
Seconds | Mapping: 161556 |

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