海洋环境因素对白冠覆盖率的影响及其数值估算

THE EFFECTS OF MARINE ENVIRONMENTAL FACTORS ON WHITECAP COVERAGE AND ITS NUMERICAL ESTIMATION

波浪破碎是一个强非线性过程,破碎时产生的大量气泡在海面上表现为白冠,白冠覆盖率是刻画波浪破碎一个重要参数。研究表明,白冠覆盖率与海上风速、海浪状态和大气稳定度等多种海洋环境因素有关。综合前人的观测数据,本文给出了更为可靠的依赖风速的白冠覆盖率公式,发现海水温度越高,白冠覆盖率越大。提出了以波浪破碎耗散函数为参数的白冠覆盖率公式,同时发现波龄小于某个临界值时,白冠覆盖率随波龄增大,波龄大于临界值时,白冠覆盖率保持不变,该临界值随风速增大而减小。

Wave breaking is a strongly non-linear process. A whitecap is a surface signature of breaking wave and air entrainment processes and is an important parameter to describe wave breaking. Previous studies show that, a whitecap coverage associates with many environmental factors including wind speed, the state of wind waves, atmospheric stability, etc. Based on previous field observational data, we developed a more reliable parameterization method between whitecap coverage and wind speed and proposed an idea that the higher the seawater temperature is, the larger the whitecap coverage is. The parameterization contains a dissipation term. Meanwhile, we find that a whitecap coverage increases with a growing wave age when wave age is below a certain threshold value and remains constant when wave age exceeds the threshold. The threshold value decreases with increasing wind speed.