Definition(s)
Mean Zero-Upcrossing Period
average period of the (up or down) zero-crossing waves in a sea state
NOTE In practice the mean zero-crossing period is often estimated from the zeroth and second moments of the wave spectrum as.
Source: API RP 2MET, Derivation of Metocean Design and Operating Conditions, First Edition, November 2014. Global Standards
Mean Zero-Upcrossing Period
average intrinsic period of the zero-upcrossing waves in a sea state.
NOTE 1 In practice, the mean zero-crossing period is often estimated from the zeroth and second moments of the wave spectrum as given by Equation (3.41-1):
where
f is the frequency in cycles per second (hertz);
m0 is the zeroth spectral moment and is equivalent to σ2, the variance of the corresponding time series;
m2 is the second spectral moment;
T2 and Tz are the average zero-crossing period of the water surface elevation, defined by the zeroth and second order spectral moments, (T2 = Tz);
ω is the wave frequency in radians per second.
NOTE 2 Adapted from ISO 19901-1:2005, definition 3.17.
Source: ISO 19905-1:202, Petroleum and natural gas industries – Site-specific assessment of mobile offshore units – Part 1: Jack-ups. Global Standards