**Sea-Bird
Zero-Crossing Statistics File Format**

The Sea-Bird zero-crossing processing steps are:

Compute Fourier coefficients (non band averaged)

apply the linear theory dispersion transfer function to each frequency

inverse Fast Fourier transform to create surface time series

apply inverse Hanning window and adjust scale factor

zero all elements where the inverse Hanning factor > 10

perform zero-crossing analysis of the surface wave time series to create an array of individual waves and periods

sort the arrays

calculate the statistics

The zero-crossing statistic files are in the Sea-Bird format that contain 3 lines of data per record. The first line contains (starting with a '*'):

Item # |
Description |
---|---|

1 |
Burst number |

2 |
Start of wave burst, seconds since 1 Jan 1989 (+ 3 days)* |

3 |
Wave integration time |

4 |
Number of points in wave burst |

5 |
Number of spectral estimates in each frequency band |

6 |
Water depth (m) |

7 |
Pressure sensor depth (m) |

8 |
Density (kg/m |

*Add 3 days since Sea-Bird program did not account for leap days (259200s).

The second line contains:

Item # |
Description |
---|---|

1 |
Total variance of time series (m |

2 |
Total energy (Joules/m |

3 |
Average wave height (m) |

4 |
Average wave period (s) |

The third line contains:

Item # |
Description |
---|---|

1 |
Maximum wave height (m) |

2 |
Significant wave height, H |

3 |
Significant period (s) (from largest third) |

4 |
H |

5 |
H |

If there are
less than 10 waves H_{1/10} is set to 0.

If there are
less than 100 waves H_{1/100} is set to 0.