Short-Term Wave Statistics

This chapter deals with the short-term statistical properties of irregular sea waves. It begins with a description of an early study by Rice [Bell Syst. Tech. J. 23, 282-332 24, 46-156 (1944, 1945)] about the relation between wave spectra and statistics of wave amplitudes. Next, an explanation is given of studies which deal with the effect of spectrum width and wave nonlinearity on wave statistics as well as with joint statistical properties between wave heights and periods. Finally, the chapter closes with a look at the statistics of wave direction, length of wave crest, and spatial maximum amphtude (which are the 3D wave s properties) as weU as the time series of wave height. 

While service loading of offshore structures results from a variety of sources, as mentioned above, the primary contributor is generally wave action. Consequently, the input spectral density function is narrow banded and in the short term the process is statistically stationary with peaks conforming to a Raleigh distribution and with Individual cycles being identifiable. Several recent experimental programs have been performed based upon such a spectrum [8-10], and one of these has reported values for D which range from 0.5 to 2.0 [8]. 

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