吉木乃县灾害性天气“闹海风”特征分析

Characteristic Analysis of Regional East Gale in Jimunai

利用吉木乃县多年的闹海风资料以及2008—2010年阿勒泰地区6个区域自动站的加密观测资料,从时空分布及地形影响等方面对局地大风天气进行了分析;普查了典型闹海风天气发生的环流形势,揭示出闹海风的形成机理,探讨了闹海风预报的着眼点。分析表明:闹海风出现在11月至翌年3月,强风集中在后冬,一般16—22时是多发时段,凌晨逐渐减小,峰值出现时间由天气影响系统而定;地域性明显,风区与峡谷的地形廓线分布相似;蒙古冷高压与中亚气旋之间的强气压梯度及特殊地形的共同作用是主要成因,本地区小尺度热低压的发生、发展对闹海风的突发起着激发作用;关注高空锋区槽脊的位置及中尺度系统的不稳定发展,同时结合区域自动站要素变化是预报闹海风的着眼点。

By use of the observation data of Regional East Gale and the observations of 6 stations from 2008 to 2009 in Aletai region,we analyzed the local strong wind for spatial and temporal distribution and the topography effect.On the basis of the circumfluence background of typical Regional East Gale,we researched on the formation mechanism and discussed the forecasting key points for Regional East Gale.The results showed that the Regional East Gale happened in November to next March.The strong winds concentrated in the latter winter,its frequent period was 16—22 p.m.commonly,and gradually reduced before dawn.Its peak value time depended on the weather influence system.The regional character was obvious and the Gale area was similar to the distribution of canyon terrain profile.The strong barometric gradient between the cold high pressure in Mongolia and the cyclone in central Asia combined with the regional special terrain was the main cause of formation for Regional East Gale.The occurrence and development of local thermal low had a strong triggered role for the outburst of Regional East Gale.The key points for forecasting Regional East Gale were to attend to the position of the trough and ridge,the unstable development of mesoscale system and the changes of meteorological element.