MESOSCALE RAINBANDS AHEAD OF COLD FRONTS IN NORTH CHINA AND THEIR DYNAMICAL MECHANISMS

Among 33 cold frontal systems passed over the Beijing-Tianjin-Tangshan area from May to August during 1963-1979,there existed mesoscale rainbands in the warm sectors ahead of 31 cold fronts.These rainbands,according to their orientation,movement,formation and development,can be divided into three types:parallel,angulate and perpendicular type.The basic characteristics,sources and propagation of the three types of rainbands and the severe convective weather associated with the bands are presented.The possible mechanisms responsible for the formation and development of the bands are also briefly discussed.