海口机场一次长时间雷雨天气过程分析

Analysis of a Long-Duration Thunderstorm Event at Haikou Airport

摘要: 海南岛极端强降水、强对流天气常导致飞机无法起降，大面积延误，对航空运行影响极大。利用常规天气资料、ERA5再分析资料和卫星云图资料等，对2023年10月11日海南岛一次长时间雷雨天气过程的主要影响系统、物理过程及形成机制进行了分析。结果表明：冷空气从中低层沿海洋南下并在华南东部沿海堆积，热带赤道辐合带对流活动显著，叠加稳定增强、西伸发展且呈东西带状的副高系统，联合提供了有利环流条件，推动低空东风急流从形成逐步走向发展与加强；低空东风急流、弱冷空气南侵、西太平洋副热带高压南侧的东风波等为暴雨的发生提供了有利的条件。在各类条件促使下，海南岛出现明显的对流列车回波效应，且整体系统移动缓慢，洋面上东风急流辐合区长时间维持，使得不断有强回波经过海口机场，造成持续时间较长的强降水伴对流天气。东风急流提供了暴雨所需水汽。对流层中层产生的正差动涡度平流扰动，动力作用与热力作用双重强迫叠加，进而引发次级环流活动，导致暴雨区上空垂直运动的发展，促使降水增强。Q矢量散度在海南岛附近辐合，0~6 km低层弱切变都有利于新生对流不断触发。此次强对流天气过程云微物理过程中占主导地位的为冷雨过程，原因为海南岛东部较强的风速脉动，促使了较强的垂直速度，将水汽带至高层，促使过冷水的有效生成，导致冷雨过程有效发展并占据了主导地位。

Abstract: Extreme heavy rainfall and severe convective weather in Hainan Island often lead to flight delays and cancellations, significantly impacting aviation operations. Using conventional meteorological data, ERA5 reanalysis, and satellite imagery, this study analyzes the main influencing systems, physical processes, and formation mechanisms of a long-lasting thunderstorm event over Hainan Island on October 11, 2023. The results show that cold air advected southward at mid-low levels along the coast of eastern South China, while convection in the tropical Intertropical Convergence Zone was active. Together with a stable, strengthened, westward-extending, and zonally oriented western Pacific subtropical high, these systems provided favorable large-scale circulation conditions, promoting the formation, development, and intensification of a low-level easterly jet. The jet, combined with southward-invading weak cold air and an easterly wave south of the subtropical high, created favorable conditions for heavy rainfall. Under these combined influences, a pronounced convective train echo effect occurred over Hainan Island. The system moved slowly, and the convergence zone of the easterly jet over the ocean persisted for an extended period, leading to repeated passages of intense echoes over Haikou Airport and resulting in prolonged heavy precipitation accompanied by convection. The easterly jet supplied abundant moisture for the heavy rainfall. Positive differential vorticity advection in the mid-troposphere, along with combined dynamic and thermal forcing, triggered secondary circulation and enhanced vertical motion over the rainfall area, thereby intensifying precipitation. Convergence of the Q-vector divergence near Hainan Island indicated conditions supporting convergent ascent at 0~6 km. The dominant cloud microphysical process during this severe convection event was the cold-rain process, attributed to strong wind pulsations over eastern Hainan Island, which enhanced vertical velocity, lifted moisture to upper levels, and promoted the efficient formation of supercooled water, allowing the cold-rain process to develop effectively and dominate.