STRUCTURAL FEATURES OF THE MEIYU FRONT SYSTEM^*

A new subtropical front near the periphery of the West Pacific subtropical anticyclone is found,which is never revealed in previous studies.The coupling of the subtropical front and Meiyu front forms a Meiyu front system (MFS) and is the most direct synoptic system for the Meiyu precipitation along the Mid-lower Reaches of Yangtze River (MRYR) in China.In this paper.The detailed structural features and cloud features of the MFS in 1998 and 1999 are analyzed,which manifests that the MFS is an objective phenomenon over the period of Meiyu along MRYR and the Southwest Japan.Generally.the subtropical front is mainly located between 850 hPa and 500 hPa.The moist southwest monsoon is transported in the passageway between the Meiyu front and the subtropical front.The vertical motion ascends in the passageway and descends on both sides of the MFS,forming the MFS's secondary circulation.A lower TBB band indicated that obvious convective activities are also located in the passageway of MFS.The horizontal wind of MFS is vertically asymmetric.