海洋白浪寿命的定义及测量结果

DEFINITION AND MEASUREMENT OF OCEANIC WHITECAP LIFETIME

通过对国内外白浪研究和应用的分析，首次提出了有效白浪寿命的定义，给出了计算白浪寿命的公式及测量方法和结果，并报告了以此方法在渤海实测的结果，得到了白浪寿命TL海面风速U10的关系为：TL=0．26U10以及白浪寿命概率分布近于瑞和分布等。

Oceanic whitecaps, resulting from wave breaking Play an importan role in affectingair-sea fluxes and marine remote sensing. So far measurements of whitecap have been limited toestablishing the relationship between whitecap coverage and wind speed. In present study, the authorsproposed a definition of average whitecap lifetime and the method of its measurement in time andspase for the first time, and also presented the method for calculating the whitecap lifetime TL, forcomparson with results from actual measarements in the Bohai Sea. Oct. 31 to Nov. 7, 1989observations were conducted from a plaiform at 39° 09′ N, 119° 42′ E in the Bohai Sea. Theobserver followed 20 whitecaps for roughly 30 min intervals at certain in the studied sea area tomeasure their 20 lifetimes and defined their average as significan whitecap lifehme. The fieldexperimen` during which wind speeds were 3 to 18.5 m/s, yielded 2 data sets.Ths study showed that whitecap lifehme, TL, increases lineary with wind speed U10, accordingto the relationship, TL = 0.26U10 while foam lifetime varies with wind velocity (with the separatingpoint at 7m/s), and increases sharply at roughly U10 = 7m/s, maximizing at about U10 = 15m/s, andthen decreases with wind velocity. The foaxn lifetime Tu = 23 s when wind velocity U10 > 7m/s and =50s when U10 > 7m/ s. It is noteworthy that the abrut increase of foam lifehme at aboutU10 = 7m/s as shown in Hgare 2b is consistent with the variation of the chaseteristic length ofbubble vertical entrainmnts ponted out by Wu (1988). The possible explanation is that the foamconsists of bubbes and hence its behavior has close relation with the bubble.The whitecap lifehme follows Rayleigh distribution, the results of a simpe empirical algorithmbased on wave brealdng probablity and whitocap lifehme to calculate whitecap coverage werecompared with Wang (1990)'s results obtained in the same place.