Based on the effective medium approximation theory of composites, the empirical model proposed by Pandey and Kakar is remedied to investigate the microwave emissivity of sea surface under wave breaking driven by strong wind. In the improved model, the effects of seawater bubbles, droplets and difference in temperature of air and sea interface (DTAS) on the emissivity of sea surface covered by whitecaps are discussed. The model results indicate that the effective emissivity of sea surface in-creases with DTAS increasing, and the impacts of bubble structures and thickness of whitecaps layer on the emissivity are included in the model by introducing the effective dielectric constant of whitecaps layer. Moreover, a good agreement is obtained by comparing the model results with the Rose’s ex-perimental data.
WEI EnBo1 & LIU Ye1,2 1 Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
The nonlinear interactions of waves with a double-peaked power spectrum have been studied in shallow water. The starting point is the prototypical equation for nonlinear unidirectional waves in shallow water, i.e. the Korteweg de Vries equation. By means of a multiple-scale technique two defocusing coupled Nonlinear SchrCMinger equations are derived. It is found analytically that plane wave solutions of such a system are unstable for small perturbations, showing that the existence of a new energy exchange mechanism which can influence the behavior of ocean waves in shallow water.
利用本征模态函数的正交分解方法对日长(LOD,length of day)数据序列进行分解,得到了日长变化的101个正交本征模态函数。通过对其中几个主要模态函数进行分析,发现日月地的相对位置与其中几个模态函数极值发生的时间极其吻合,并据此推断出日长变化的主要激发源。同时还发现日长变化存在准周期约为206 d的波动。
