摘要
针对2007年7月29～30日发生在山西省垣曲县的特大暴雨天气过程,利用实况资料、自动站资料以及GMS红外卫星云图,计算了地形性垂直速度、切变涡度、散度、能量,并分析了其分布及演变特征,对前期500 hPa高度和温度进行了合成分析,结果表明：（1）前期500 hPa阻塞高压和切断低压的形成和长期维持,使得冷空气在山西上空堆积,形成强烈的高空冷涌;同时,副热带高压的稳定加强、维持为暴雨提供了能量积累和水汽来源,致使山西出现大范围降水和区域暴雨天气。（2）K-H不稳定的形成和维持,是导致中尺度切变线上小尺度涡旋维持、加强,并产生强风暴雨的重要原因。（3）垣曲县特殊的地形,使得其附近流场发生变化,不仅使地形性垂直上升运动加强、维持,而且也使得水汽不断向云内卷入,延长了暴雨云团在其上空的停留时间;同时通过云物理作用,使得已经凝结的水分高效率地下降,从而增加降水量;喇叭口地形的收缩作用也加强了迎风坡的辐合上升运动。
Take a rainstorm occurred in Yuanqu county, Shanxi from 29 to 30 July 2007 as a case, based on the observed data, automatic meteorological data, and GMS infrared satellite image, the development characteristics of terrain vertical velocity, shear vortex, divergence, and energy were analyzed. The 500 hPa heights and temperature before rainstorm were combined and analyzed, combining experimental results by numerical model, all shows that： （1） The forming and long-term maintaining of block high and cutting low at 500 hPa before rainstorm made cold air pile up over Shanxi, and so strong cold gushing was formed. Meanwhile, the strengthening and maintaining of West Pacific subtropical high offered energy and water vapor source for the rainstorm. Under background of the above special weather, regional rainstorm and heavy rain in large scope in Shanxi were occurred, and the center of heavy rainstorm located on the windward side of the mountain. （2） In the shear cloud band, there were a series of mesoscale rainstorm cloud cluster formed which arranged in a band along Taihang mountain. The wind convergence at lower levels by special terrain of Yuanqu made water vapor draw into cloud and caused rainstorm cloud cluster forming and developing continually. The rainstorm in Yuanqu county was caused directly by the γ-mesoscale rainstorm cloud cluster in the shear cloud band. （3） The air flow field near Yuanqu county was changed by its special terrain. It can not only help the mesoscale disturbance form and develop under the advantageous weather condition, but also make terrain vertical velocity strengthen and maintain. It can also make water vapor draw into cloud and so prolong the durian time of rainstorm cloud above Yuanqu county. It can make coagulated water drop efficiently by physical process of cloud and so increase rainfall. The shrink of trumpet terrain was important, too. （4） The forming and maintaining of K-H instability was an important reason of causing vortex on the shear line maintain, strengthen, and causing rainstorm. While the special terrain in Yuanqu county made K-H in stability strengthen and maintain. （5） There was a saddle structure of θse at the vertical profile and a dustpan of high energy area above the rainstorm area. The energy front sloped towards the north and convective instability developed deep. The action between strongly releasing of high instability and low cloud on the side of facing wind of the mountain each other made rainfall increase and it was an important reason of rainfall near Yuanqu larger than other areas.
出处
《高原气象》
CSCD
北大核心
2009年第4期897-905,共9页
Plateau Meteorology
基金
中国科学院大气物理研究所LASG实验室开放课题"基于条件非线性最优扰动的暴雨集合预报试验"
山西省气象局重点科研项目(0509
0702)共同资助
关键词
阻塞高压与切断低压
K-H不稳定
地形
晋南特大暴雨
Block high and cutting low
K-H instability
Terrain
Extremely rainstorm in Southern Shanxi
