江西秋季一次区域性强对流天气过程的模拟分析

利用常规地面观测资料、卫星辐射率资料以及NCAR/NCEP再分析资料,采用中尺度数值模式WRF及其三维变分同化模块,对2009年11月9日江西的一次区域性秋季强对流天气过程进行数值模拟,探讨了此次强对流天气过程发生发展的物理机制。结果表明:(1)江西省基本均处于K指数大于36℃高值区,具备热力不稳定能量,K指数很好地反映此次过程的热力条件;(2)强的垂直风切变,为此次强对流提供发展的能量;(3)Δt850-500达到26℃,具有强垂直温度梯度;(4)此次强对流过程中,对流层中高层的干侵入可以向下伸展至700 hPa高度层以下,有利于对流不稳定能量在低层的积聚,对流不稳定能量的释放可以将低层的暖湿气流向上输送至较高的层次,加强了强对流天气的发生。

NUMERICAL SIMULATION OF A STRONG CONVECTIVE PROCESS OF JIANGXI IN AUTUMN

Based on conventional data,satellite radiance data and NCAR/NCEP reanalysis data,WRF model is used to analyze the 9 November 2009 strong convective process in Jiangxi.The result shows that:(1) The K-index is larger than 36 ℃ in Jiangxi,which can indicate the thermal conditions of this process.(2) The strong vertical wind shear provides strong energy for this severe convective.(3) Δt850-500 reaches 26 ℃,which means that the vertical temperature gradient is very big.(4) During this process,the dry air intrusion in upper troposphere extends below 700 hPa,which is favorable to unstable energy accumulating in the lower troposphere.Energy release from convective instability can transport humidity air from lower level to higher level and trigger the severe convective weather.