Both observations and numerical simulations have proven the existence of a plume bulge at the trumpet-like Pearl River Estuary (PRE). The formation dynamic of the PRE plume bulge during the southeasterly wind period is investigated with numerical model simulations based on the Regional Ocean Modelling System (ROMS). The results indicate that the formation and evolution of the PRE plume bulge is strongly modulated by the tidal cycle. The bulge is sustained by the strong jet flow along the longitudinal Lantau Channel, which is induced by the ebb current, and transports freshwater offshore. Its size is significantly modulated by spring-neap cycle, being large during spring tide and very small during neap tide. Besides, the existence of abundant freshwater in the estuary is a precondition for the formation of bulge. The ebb jet flow could be strengthened by lateral buoyancy forcing, which is induced by the accumulated freshwater in the estuary, thus guarantees the offshore extension of bulge. The input momentum flux by the river runoff, however, makes no significant contribution. The work indicates a new mechanism of plume bulge formation at a wide estuary and evaluates the impact of different forcings.

观测和数值模拟都证明了在喇叭状的珠江口（PRE）上存在羽状凸起。利用基于区域海洋模拟系统（ROMS）的数值模拟，研究了东南风期间PRE羽状凸起的形成动态。结果表明，PRE羽状凸起的形成和演化受到潮汐周期的强烈调节。沿纵向大屿山河道的强烈射流支撑着隆起，这是由退潮引起的，并将淡水输送到近海。它的大小受春潮周期的影响很大，在春潮时较大，在春潮时很小。此外，河口中丰富的淡水的存在是形成隆起的前提。河口堆积的淡水可引起侧向浮力，从而增强退潮，从而保证了船头向海上延伸。但是，河流径流的输入动量通量没有太大贡献。这项工作表明了在宽河口形成羽状隆起的新机制，并评估了不同强迫作用的影响。