台风"碧利斯"影响庐山降水的探测资料分析

通过分析台风“碧利斯“影响江西期间的自动气象站资料和雷达回波特征,探讨了造成庐山过程强降水较周围雨量明显偏多的原因.研究结果发现,“碧利斯“过境时,雷达回波强度在庐山会有加强的现象,径向速度场表现为有风向和风速的切变存在;零等速度线的走向变化和降水的变化有关,且零等速度线的变化往往先于降水的变化,能预示降水的变化趋势.除“碧利斯“本身携带的大量水汽外,庐山迎风坡的地形抬升作用,以及鄱阳湖水域充沛的水汽供应,是造成这种现象的根源;中小尺度辐合在庐山较长时间的维持,是造成庐山降水普遍大于周边地区的根本原因.

ANALYSIS OF THE RAINFALL DATA ON LUSHAN INFLUENCED BY THE TYPHOON "BILLS"

Based on the analyses of automatic meteorological station data and Doppler radar products during the typhoon "BILIS",the reason was discussed why the total rainfall on Lushan was larger than the adjacent region.The result shows that judging from the character of Doppler radar products during the time when the severe tropical storm influenced the region around Lushan,reflectivity will raise concomitant with its passing over the mountain,simultaneously obvious change of wind direction and velocity in small region.The change of uniform zero velocity line often keep ahead of the change of precipitation.In other words,the change of zero velocity line generally prefigures the change of precipitation.The reason why the accumulative rainfall amount is larger on the Lushan is not only the plenty of water vapor from "BILIS" itself,but also the windward slope of Lushan and the rich water vapor supplied by Po-yang Lake.The longtime existence of small-scale convergence is the fundamental reason why the total rainfall on Lushan was larger than the adjacent stations.