梅汛期低涡统计及与浙北暴雨的关系

Relationship of Vortex Characteristics in Meiyu Season and Heavy Rain Events over Northern Zhejiang

应用2004-2013年NCEP/NCAR再分析资料和浙江北部雨量资料,对梅雨期间低涡活动进行统计分类,并对低涡与浙北暴雨的关系进行了分析.结果表明：梅雨期平均每年有5.6个低涡活动,夜间02时生成的低涡最多,早晨最少,低涡生命期多在24-48 h之间;依据涡源,低涡可分为三类,其中西南涡最多,占总数的42%,生成后向东北方向移动;有低涡影响的暴雨约占暴雨总数的63%,其中73%受西南涡影响,且发生在夜间的暴雨受低涡影响概率比白天大;低涡东南侧暖区暴雨比低涡后部冷切暴雨略多,暖区暴雨发生时,低涡中心多位于安徽省,最远距浙北约400 km,高空多小槽活动;而在冷切暴雨中,切变线距离浙北200 km以内,75%的西风槽已移至我国东部沿海.

Based on the NCEP/ NCAR reanalysis data from 2004 to 2011 and northern Zhejiang rainfall data, we analyzed the characteristics of vortexes and their relationship to heavy rain events. The results showed that there was about 5.6 vortexes per year in Meiyu season, the vortex generated at most in the night and at least in the morning, most of vortex survivaled 24~48h. The vortex can be divided into three categories, most of vortex belonged to southwest vortex which accounted for 42%of the total and moved to the northeast after generation. The heavy rain was effected by vortex in the night more than in the daytime which was approximately 63% of the total rainstorm and 73% by southwest vortex. The warm rainstorm appeared in southeast of the vortex slightly more than the rainstorm in back of the vortex, the vortex center was located in Anhui province when the warm rainstorm happened and the most distant from north Zhejiang about 400km, but in the other type of rainstorm, the shear line distances within 200km to north Zhejiang.