摘要
从深对流发展必须满足的对流层低层有足够强的湿层、层结不稳定和足够强的触发机制出发，对2002年7月11～15日由东北冷涡诱发的一次连续强风暴生成的环境条件进行了诊断分析。结果表明：低层暖湿条件是冷涡强对流预报的关键．强大的冷涡由于冷性层结深厚难以诱发强的对流性天气，而其分裂的次涡度中心或弱的冷性低涡配合低层暖湿气流常常产生突发性强对流性天气；强的风垂直切变引发的斜压不稳定和垂直运动是强对流触发和维持的重要条件，风暴发生前边界层到500hPa风向随高度顺转超过90°，随着对流性天气的发展，850hPa以上风垂直切变逐渐减小，而850hPa以下可能受低层冷丘产生中高压的影响，切变有增大的趋势；冷涡诱发的强对流性天气常常位于高空急流出口区左侧，但在实际预报业务中需要配合散度场来进行综合判断。
From three elements of deep convective development, i. e. strong enough wet layer, stratification instability and strong enough trigger mechanism, the environment conditions of a continual rainstorm caused by northeast cold vortex from 11 to 15 in April 2002 was analyzed. It could be concluded that warm and wet conditions played an important role to the severe convective forecast of cold vortex,and strong cold vortex could seldom bring severe convective weather for the cold stratification profundity. However ,subsidiary vortex divided from cold vortex and weak cold vortex related to warm and wet conditions in low layer could often bring abrupt severe convective weather. Baroclinic instability and vertical motion caused by strong wind vertical shear were the important conditions to severe convective trigger and maintenance. Wind direction veered 90 degree with altitude from boundary layer to 500 hPa before the storm occurred. With the development of convective weather, the wind vertical shear over 850 hPa gradually decreased, while the wind vertical shear under 850 hPa gradually increased because of the impact of the middle and high pressure caused by low layer cold stack. The severe convective weather caused by northeast cold vortex often lay in the left of upper jet exit. But the divergence field must be considered in real forecasting operation.
出处
《气象与环境学报》
2006年第6期1-5,共5页
Journal of Meteorology and Environment
基金
国家自然科学基金项目(40375020)资助
关键词
东北冷涡
强风暴
强对流
诊断分析
Northeast cold vortex
Rainstorm
Severe convective
Diagnosis analysis
