摘要
利用NCEP/NCAR再分析资料,通过对2012年7月中旬我国中东部地区持续性强降水过程中东亚夏季风系统中主要成员的时空变化特征进行分析。结果表明,此次持续性强降水期间,副高北界、南亚高压脊线及中纬度锋区位置相对稳定,长江中下游地区一直处于南亚高压反气旋环流东侧偏北风与西风槽前偏南风之间的风向开口辐散区中;副高南撤时,强降水主要位于584 dagpm线北侧,副高北抬时,强降水主要位于584 dagpm线南侧;此次持续性强降水发生前期,大气为上干下湿不稳定层结,当西风带低槽频频携带冷空气南下影响,同时低空西南急流反复加强,其出口区左侧较强的风速梯度为暴雨的发生发展提供了动力条件;低层干空气的不断侵入,低槽和低涡间的垂直正反环流促使垂直上升运动维持或发展,进而造成持续性强降水;高空西风急流加强（减弱）超前低空西南急流加强（减弱）2~5 d,对持续性强降水有超前指示意义。
Using the NCEP/NCAR reanalysis data, the temporal and spatial variation features of the leading members of the East Asian stunmet monsoon system during the durative heavy precipitation at the middle east area of China in mid-July 2012 was analyzed. The resuhs showed that, the position of North boundary of subtropical high, the south ridge line and the midlatitude frontal zone were relatively stable during the persistent heavy rainfall. Middle and lower reaches of the Yangtze River has been in the divergenee zone of the northerly wind of the South and the southerly wind of the trough. When the subtrupical high moving southwrad, the tleavy precipitation often oeeured the nurdl of lhe 584 line; while the subtropical high moving northwrad, the heavy precipitation often occured the south of the 584 dagpm line. Before the per- sistent heavy rainfall occured, the atmosphere was unstable stratific, ation. The cold air of westerly trough frequently carried and /he warm air of the Southwest Jet at low altitude repeatedly carried, which the strong wind speed gradient ~ff the left of exit region has provided the impetus for the development of storm conditions. The intrusion of dry air at low-level, the front and back vertical circulation of the trough and the Vortex maintained the upward vertical movement, and the persistent heavy rainfall had developed. Upper-level westerly jet strengthened （weakened） before Southwest Jet at low altitude to strengthened （weakened） fur 2 -5 d, that had a ahead of significance for durative heavy precipitation.
出处
《安徽农业科学》
CAS
2014年第31期11028-11032,11107,共6页
Journal of Anhui Agricultural Sciences
关键词
持续性强降水
形成机制
高、低空急流
冷空气
垂直环流
Persistent heavy rain
Formation mechanism
Upper aml lower-level jets
Cold air
Vertical circulation
