Our recent study reported the existence of internal solitary waves with the diurnal tidal cycle (ISW-D) in the Sulu Sea, however, the three-dimensional characteristics and generation mechanism of ISW-D are still unclear (Huang et al., 2023). In this work, the spatial–temporal characteristics, generation mechanism and propagating process of ISW-D in the Sulu Sea are first preliminary investigated based on high-temporal-resolution Geostationary Orbiting Satellite (GOS) images and high-spatial-resolution two-dimensional numerical model (MITgcm). GOS images from 2018-2022 are retrieved and a total of 13 pairs of ISW-D packets are found. ISW-D occur at spring tide during May–August, with an average interpacket distance of 198 km and a phase speed of 2.30 m/s. To further knowledge of the generation mechanism and propagation process of ISW-D, the non-linear and non-hydrostatic numerical simulations are conducted. The comparison of ISW-D parameters with GOS images proves the validity of numerical simulations. The results of numerical simulations and theoretical parameters indicate that ISW-D are generated at the sill near Pearl Bank by internal tide release mechanism. Moreover, three sensitivity experiments are designed to investigate the effects of tidal force and seawater stratification on the generation and propagation of ISW-D. The results reveal that the ISW-D is generated by diurnal tides with stronger intensity than semidiurnal tides. Seawater stratification does not influence the generation of ISW-D but modulates the propagation process. Phase speeds from GOS images and theoretical model show a positive correlation between the phase speeds of ISW-D and the intensity of seawater stratification.

中文翻译：

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苏禄海日间内孤立波（ISW-D）的产生：来自地球静止轨道卫星和数值模拟


我们最近的研究报道了苏禄海存在具有日潮汐周期的内孤立波（ISW-D），但ISW-D的三维特征和产生机制仍不清楚（Huang et al., 2023） 。本工作首先基于高时间分辨率地球静止轨道卫星（GOS）影像和高空间分辨率二维卫星图像，初步研究了苏禄海ISW-D的时空特征、产生机制和传播过程。数值模型（MITgcm）。检索2018-2022年的GOS图像，共找到13对ISW-D数据包。 ISW-D发生在5月至8月的大潮期间，平均包间距离为198 km，相速度为2.30 m/s。为了进一步了解ISW-D的产生机制和传播过程，进行了非线性和非静水力数值模拟。 ISW-D参数与GOS图像的比较证明了数值模拟的有效性。数值模拟结果和理论参数表明ISW-D是通过内潮释放机制在珍珠滩附近的岩台产生的。此外，还设计了三个敏感性实验来研究潮汐力和海水分层对ISW-D产生和传播的影响。结果表明，ISW-D是由强度比半日潮更强的日潮产生的。海水分层不会影响ISW-D的产生，但会调节其传播过程。 GOS 图像和理论模型的相速度显示 ISW-D 的相速度与海水分层强度之间呈正相关。