为了研究东沙环礁附近海域第二模态内孤立波的生成机制,基于非静压海洋模型SUNTANS,在南海实际地形条件下建立了南海东北部内孤立波三维数值模型,对该海域内孤立波的传播演变进行了数值模拟.模型模拟出了第二模态内孤立波,其垂向呈三层结构,即上层水体与下层水体水平向流速相同,并与中间层相反.第二模态内孤立波波速模拟值与理论计算值吻合较好.根据模拟结果,分析了东沙环礁附近海域第二模态内孤立波的生成过程,结果表明,该海域第二模态内孤立波源于从吕宋海峡附近海域传播而来的第一模态内孤立波和底部地形的相互作用,并与陆坡上部内潮的影响有关.
In order to investigate the generation mechanism of the second mode internal solitary wave in the ocean area near Dongsha Atoll,based on non-hydrostatic model SUNTANS,a three-dimensional numerical model,which is based on actual bathymetry data,is developed to simulate the propagation and evolution of internal solitary waves in the northeastern South China Sea.The simulated results indicate that the horizontal velocity in the middle layer,induced by the second mode internal solitary wave,is in the opposite direction to those in the upper and lower layer.The calculated propagation speeds of the second mode internal solitary wave agree well with results of theoretical analysis.The generation process and mechanism of the second mode internal solitary wave in the ocean area near Dongsha Atoll are analyzed using the numerical results.The second mode internal solitary wave is generated by the interaction between the first mode intemal solitary wave,arising from the Luzon Strait,and bottom topography combined with the influence of internal tide.