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利用常规观测资料、卫星观测的高时空分辨率TBB资料以及客观分析资料,对2002年6月22～23日(“02.6”)一次非典型的梅雨锋暴雨过程进行了天气分析.在此基础上,利用中尺度数值模式MM5对此次梅雨锋暴雨过程进行了数值模拟,并分析了暴雨中尺度系统的结构特征.结果表明:(1)天气分析显示,“02.6”梅雨锋暴雨过程与α中尺度低涡的东移发展和对流层低层的两支低空急流的增强发展有关.对流层低层700 hPa为一个缓慢东移与南压的东北西南向冷式切变线,暖式切变线不太明显,这与通常的江淮切变线梅雨锋暴雨不同.对流层500 hPa的副热带高压非常强,高层200 hPa对流层高层的反气旋环流非常强并与高空急流相伴,南亚高压中心位于我国江南地区.(2)TBB资料分析表明,此次暴雨过程产生与多个β中尺度系统合并发展成α中尺度系统以及此后从α中尺度系统中不断分裂出β中尺度系统发展演变密切相关;强中尺度对流系统主要在中尺度低涡冷、暖切变线的的南侧发生和发展,并不是在中尺度低涡的冷暖切变线上发展.(3)垂直结构分析显示:在中尺度系统开始发展阶段,中尺度系统具有强的垂直于剖面的风分量切变、低空急流核以及高空强辐散低空强辐合,这有利于中尺度系统的发展;当中尺度低涡发展到相对成熟的阶段,其后部不断分裂出中小尺度系统,对流层低层的θ_e具有明显暖心结构,由于气块绝热上升冷却效应比对流潜热释放作用强,导致在800～600 hPa层上θ_e比环境的低,加之在强上升运动的顶部两侧的下沉补偿气流也比较弱,这不利于中尺度低涡的维持.“,”The routine observational data,high spatial-temporal data on Temperature of Black Bold observed by satellite and objective analysed data are used to analyze and simulate a nontypical Meiyu front rainstorm which occurred from 22 to 23 June 2002(“02.6”). It is found that the occurrence of “02.6” Meiyu front has closely relation with the development of meso-α-scale vortex and double low level jet at low level of troposphere,a cold shear line appeared on 700 hPa which is differ with the normal shear line of Meiyu front rainstorm over Changjiang River basin. The analysis of TBB indicates that the produce of the rainstorm has close relation with combination of several meso-β-scale systems into meso-α-scale system and abruption of meso-β-scale systems from the mesoscale vortex. The intense ascending movement mainly occurred in the southern of cold and warm shear lines and not in the cold and warm shear lines. Analyses of vertical structure show that the mesoscale systems have strong vertical shear of wind,low level jet core,strong convergence at low levels and intense divergence at upper levels,which favored the development of mesoscale system at initial phase;several mesoscale systems sbrupted from the meso-α-scale system when the mesoscale system reached its mature phase,the distribution of θ_e at low levels has a warm core;the weak downward flows located on two sides of upward flow which made against the development of mesoscale vortex.