ISSN:
1573-868X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
Notes:
Abstract Water surface elevationsη(t), vertical surface velocities $$\dot \eta (t)$$ and vertical surface acceleration $$\dot \eta (t)$$ of wind-generated waves have been measured in a laboratory wind wave channel by using resistance-type wave gauges combined with an electronic differentiation circuits. Probability distributions of the values ofη(t), $$\dot \eta (t)$$ , and $$\ddot \eta (t)$$ have been determined from the wave records. In an initial stage of wave generation,i.e., when wind waves are generated at short fetches and low wind speeds, the observed distributions forη(t), $$\dot \eta (t)$$ and $$\ddot \eta (t)$$ are appreciately good fit to the distributions given by successive sum of a Gram-Charlier series, which has been derived following the formulation ofLonguet-Higgins (1963), by taking the weakly nonlinear effect into account. However, when wind waves develop with increasing wind speeds and fetches, the observed distributions deviate gradually from the Gram-Charlier series. Particularly, the deviations are remarkable for the distribution of $$\ddot \eta (t)$$ . When the wind speed increases, the observed distributions ofη(t), $$\dot \eta (t)$$ and $$\ddot \eta (t)$$ show the following characteristics: (i) the skewnesses of the distributions ofη(t) and $$\dot \eta (t)$$ decrease slightly, (ii) the skewness of $$\ddot \eta (t)$$ changes, at some wind speed, from positive small values to relatively large negative values, (iii) the kurtosis of the distribution ofη(t) decreases slightly but that of $$\dot \eta (t)$$ increases slightly and these characteristics seem to depend not so much on fetches, (iv) the kurtosis of the distribution of $$\ddot \eta (t)$$ increases rapidly.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02107991
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