摘要
利用NCEP/NCAR再分析资料、TBB资料、探空资料及多普勒雷达资料等对2003年4月12日发生在江西以及福建北部的强对流天气过程进行了诊断分析。结果表明:此次强对流天气过程是在高空槽和低层低涡切变线的有利形势下产生的,这种下层暖湿、上层干冷的对流不稳定层结非常有利于强对流天气的产生;强对流天气发生发展伴有多个中尺度对流云团东移南压的演变过程;多普勒雷达资料分析表明,冰雹发生时可观测到79 dBz的反射率因子极值并伴有弓状回波;对流有效位能积累、释放随时间的演变过程,对于此次强对流天气过程有很好的指示意义;强对流天气发生前高层的干冷空气倾斜状向下侵入到对流层中低层附近,对此次强对流天气的发生发展起了非常重要的作用;能量锋区及锋区上强的垂直涡柱为该次强对流天气过程提供了有利的热力和动力学条件。
Convection weather is one of the most severely disastrous weather phenomena in China, with features of small spacial scale, short life span, sudden emergence and great damaging force. It is always very difficult to make an accurate analysis and forecast for severe convection weather in the daily operational work. With the application of Doppler radar and the development of numerical weather prediction technology, the knowledge about the severe convection weather and the related mechanisms is also improved in recent years. Effective ways have been developed in some countries to be applied in the analysis and forecast for severe weather. Examples can be found in U S A, where parameter estimation, graphics identification and statistical characteristics based on climate have been put into operational use for forecast of hailstones and tornadoes, and proved to be useful in improving the accuracy. Much improvement is also made in China Meteorological Administration in recent years in severe weather observation, many new instruments, such as radars, automatic weather stations, lightening detection and GPS/MET vapor detection instruments etc have been gradually put into operational use. These new data definitely provide forecasters and researchers good opportunities to study the severe convection weather and improve the forecast accuracy. Using NCEP/NCAR daily meteorological reanalysis data, sounding data, TBB and Doppler radar images, a typical convection induced severe weather process occurred on April 12-13, 2003 in Jiangxi and northern Fujian is diagnosed and analyzed, the result shows that this severe convection weather takes place under favorable conditions of upper trough coupling with a low-level vortex and shear environments. Lower level southwesterly jet contributes as a vapor transportation passage. Dry and cold airs of upper level overlapping upon wet and warm airs in lower level create a convectively unstable layer. Under this condition, convective weather could be easily initiated and high instability energy releases with suitable triggering mechanism. Several mesoscale convective clouds involve in the development of the severe weather, and deep convection mostly concentrates on the frontal parts of the clouds where TBB isolines converging with high gradient. Also the Doppler radar images show that the maximum reflection up to 79 dBz is reported during hail-fall, and bow echo could be observed. Convective available potential energy （CAPE） is a meaningful sign in the process of convection event. Before the severe weather, CAPE grows gradually and accumulates. The severe weather initiates soon after the CAPE reaches its peak values, then with CAPE＇s releasing and becoming weak rapidly, severe weather downgrades. Dry air intrusion to mid-level from upper level plays an important role in the development of convection. Energy-front zone and strong vertical vorticity-pole provides thermodynamic and dynamic conditions for this severe convection weather.
出处
《应用气象学报》
CSCD
北大核心
2007年第4期460-467,共8页
Journal of Applied Meteorological Science
基金
国家自然科学基金项目(40205008)
国家气象中心课题(LD-05
ZK2002A-02)共同资助
