摘要:登陆台风Matmo（2014）北侧弱回波区突发多条强对流雨带，造成严重影响。本文利用NECP/NCAR的FNL（Final）再分析资料，地面自动站加密观测资料、雷达拼图资料等对台风北侧连续出现的3条对流雨带的触发和发展过程进行研究。结果表明：初始对流是在弱的对流不稳定和条件对称不稳定条件下，由锋面强迫和地形抬升作用共同触发。接二连三发生的3条对流雨带是在台风北部高湿环境，长时间稳定的水汽辐合，明显的对流不稳定，局部弱条件对称不稳定条件下，由近地面辐合线在辐合稳定并加强后触发的，有利的环境和多层不稳定的叠加有利于雨带的发展和维持。先后触发对流雨带的3条辐合线在发生位置上相当接近。辐合线的形成一方面由海陆下垫面差异、江苏和山东南部海岸线曲率、台风风速随半径分布特点所决定；另一方面，辐合线2和3的形成还与它们北侧对流雨带的冷出流密切相关。对流带上的强降水中心往往对应着稳定的辐合中心，辐合中心主要位于风速大小梯度明显的位置上。而辐合线上的风速梯度主要受海岸线、地形附近的降水分布影响。
关键词:登陆台风/
雨带/
触发/
辐合线
Abstract:Three strong convective rainbands suddenly initiated and developed to the north of the landfalling typhoon Matmo (2014), where radar echoes were weak at the initial time. The intense convective precipitation later led to serious disasters over this region. The mechanisms for the convection triggering and developing processes are studied using the NCEP/NCAR final reanalysis data, automatic observation data and radar reflectivity data. Results show that the low-level frontal forcing combined with orographic lifting triggered the initial convection under the condition of symmetric instability and weak conditional convective instability. The rainbands were triggered by three convergence lines near the ground and kept developing when the convergence intensified under the circumstances of high humidity, persistent moisture convergence, and obvious convective instability accompanied with weak conditional symmetric instability. The forming positions of the three convergence lines are quite similar, which might be attributed to the difference in surface roughness between land and sea, the coastline curvature of northern Jiangsu and southern Shandong province, and the distribution of typhoon wind speed with radius. On the other hand, the generation of the second and third convergence lines was also closely related to the cold outflow from the previously formed convective rainband to its north. Strong precipitation centers along the convective rainbands often correspond to stable convergence centers that are located in the area with large wind velocity gradient. The wind speed gradient along the convergence line is mainly affected by the distribution of coastline, topography, and precipitation in the surrounding area.
Key words:Landfalling typhoon/
Rainband/
Convective initiation/
Convergence line
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