Focusing of sunlight by sea surface waves: new results from the Black Sea*
Focusing of sunlight by sea surface waves: new results from the Black Sea*
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海面波浪聚焦阳光：黑海的新结果*
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C. Scarre
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作者：
C. Scarre
在晴朗的天空下，由于表面波对太阳光的聚焦和散焦，向下的辐照度Ej在浅水中普遍存在强烈波动。这种时间波动是在黑海测量的，通常在1米深，从离海岸线600米的一个固定平台上测量。对109条ED(525 Nm)时间序列记录进行阈值分析，每条记录持续10min。随着闪光强度的增加，强闪光的发生频率(强度超过时间平均照度ED的50%)呈指数下降。闪电的频率和强度，也就是指数关系的斜率，都随风浪条件和大气照度而变化。最佳聚波条件为：S风速2~5m，太阳高度40°，表面辐照度40%。然后，在1米深处，闪光以高达6赫兹的速度发生。在10~3赫兹频率下，最强烈的闪光超过ED的5倍。这篇论文在1992年圣迭戈举行的海-气界面光学会议上提交了SPIE的光学应用科学和工程国际研讨会，类似的文本被印刷在SPIE会议论文集，第1749卷，第65-72页。这项研究由波兰国家研究委员会在波兰科学院海洋研究所海洋光学方案的框架内与设在塞瓦斯托波尔的乌克兰科学院海洋水文物理研究所合作支持。《海洋学》，第34期，第13-25页，1993年。PL ISSN 0078-3234水下闪光海洋光学与我们之前的观察结果，大大改善了关于仍然缺乏记录的波聚焦效应的数据库。
Under clear skies, strong fluctuations in the downwelling irradiance E j prevail in shallow water as a result of the focusing and defocusing of sunlight by surface waves. Such temporal fluctuations were measured in the Black Sea, usually at a depth of 1 m, from a fixed platform located 600 m off the coastline. Thresholding analysis was applied to 109 time-series records of Ed(525 nm), each of which lasted 10 min. The frequency of occurrence of intense foci flashes (intensity exceeding the timeaveraged irradiance Ed by > 50 %) decreased exponentially with increasing flash intensity. The frequency and intensity of flashes, hence the slope of the exponential relationship, both varied with wind-wave conditions and atmospheric illumination. The best conditions for wave focusing were characterised by light winds o f 2 to 5 m s-1 , solar elevation > 40°, and diffuseness of surface irradiance < 40%. Then, at a depth of 1 m, flashes > 1.5 Ed occurred at rates as high as 6 Hz. The most intense flashes exceeded Ed 5-fold at rates of 10~3 Hz. These results, consistent * This paper was presented at SPIE’s International Symposium on Optical Applied Sci ence and Engineering at the * Optics of the Air-Sea Interface ’ Conference, San Diego, 1992 and a similar text is printed in the Proceedings SPIE, vol. 1749, pp. 65-72. This study was supported by the Polish National Research Committee, within the framework of the Marine Optics Programme of the Institute of Oceanology of the Polish Academy of Sciences in cooperation with the Marine Hydrophysical Institute of the Ukrainian Academy of Sciences in Sevastopol. OCEANOLOGIA, No. 34 pp. 13-25, 1993. PL ISSN 0078-3234 Underwater flashes Marine optics with our previous observations, substantially improve the database on still poorlydocumented wave focusing effects.