摘要:本文针对1323号强台风“菲特”螺旋云带中出现“列车效应”的特征及形成开展了分析研究。研究发现，浙江钱塘江湾南岸持续性降水中具有“列车效应”特征，按照雨带的稳定位置，将其分为两次“列车效应”过程，时间跨度都在3～4小时左右，空间跨度在1～2个经度距离；暴雨区呈现出带状特征，降水效率高，每小时降水超过25 mm并向前线性传播；台风螺旋云带中强度在35 dBZ以上的雷达回波平均反射率也呈现线性带状结构；降水带走向和雷达回波运动方向与台风中心运动方向产生了大致在25°以上的向右偏离。从“列车效应”的形成来看，高空引导气流的方向和地面中尺度扰动辐合带走向与“列车效应”中对流单体运动方向基本一致，为其呈近线性排列提供依据。沿海形成的中尺度扰动辐合或扰动涡旋，为螺旋云带中对流在沿海地区发生或发展提供重要条件，形成了对流云的快速增长和后续发展的启动和维持机制，对于“列车效应”的形成、发展和维持起了重要作用。
关键词:螺旋云带/
列车效应/
台风暴雨/
中尺度滤波/
中尺度辐合
Abstract:The characteristics and formation of “train effect” in the spiral cloud belt of typhoon “Fitow” (No. 1323) are analyzed in this paper. The results show a “train effect” occurred during persistent rainfall over the south bank of the Qiantangjiang Bay in Zhejiang. According to the stable position of the rain belt, This rain process can be divided into two “train effect”. Each “train effect" last about 3–4 h, and the space span is 1–2 longitude distance. The rainstorm area shows the characteristics of band, with high precipitation efficiency. The precipitation exceeds 25 mm h?1 and propagates forward linearly. The average reflectivity of radar echo in the spiral cloud belt of typhoon with over 35 dBZ also shows a linear band structure. The trend of precipitation belt and radar echo deviated from the typhoon center by more than 25° to the right. From the formation of the “train effect”, the direction of the high-altitude guided airflow and the direction of the surface meso-scale disturbance convergence zone are consistent with the movement direction of the convective cell in the “train effect” providing the basis for its nearly linear arrangement. The meso-scale disturbance convergence or vortex formed along the coast provides important conditions for the occurrence or development of convection in the spiral cloud belt in coastal areas. This convergence also forms the beginning and maintenance mechanism for the rapid growth and subsequent development of convective clouds, playing an important role in the formation, development, and maintenance of the “train effect”.
Key words:Spiral cloud belts/
Train effect/
Typhoon rainstorm/
Meso-scale filtering/
Meso-scale convergence
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