“5.5”黑风暴中-β尺度飑线的初步数值模拟

NUMERICAL SIMULATION OF A MESO-βSQUALL LINE ON THE “5. 5” DARK STORM

中文关键词:  黑风暴  中-β飑线  模拟

英文关键词:Dark storm  Meso-β squall  Simulation

中文摘要:

      利用改进型PSU/NCAR中尺度模式,以常规观测资料作为初值,较好地模拟了"5.5"黑风暴过程的重要影响系统中-β尺度飑线的主要特征,即近地面风场切变线,与切变线相伴的风核、狭窄强对流带、强水平温度、气压梯度带以及上述特征带(线)的形成、迅速增强的时间和移动方向,模拟显示这是一条降水很小的"干"飑线,从全物理过程和不考虑水汽的干模式对比来看,云降水过程在本例飑线中没有起到决定性作用。飑线垂直结构的初步模拟揭示,飑线温度水平剧烈变化及垂直上升速度中心都在对流层低层的700hPa(地形高度在850hPa),垂直环流随高度向后倾斜。中低层短波扰动引起的槽后强冷平流在飑线后下沉是飑线发展的重要机制。

英文摘要:

      On 5 May 1993,a dark storm (strong sandstorm) recorded rarely in the history took place in northwest of China and took a large toll in human life and property damage .This event brought on general attention in the world .The meso-scale squall is an important influence system of "5.5" dark storm .By using of improved PSU/NCAR mesoscale model with 15-km grid interval,the operational rawinsonde observations as initial data,we simulated successfully the main characteristics of the squall,including surface wind shear-line,storm center related with the squall,strong and narrow convective zone,strong horizontal temperature and pressure gradients as well as the time of their formation and rapid reinforcement and moving direction .The vertical structure of the simulated squall revealed that the largest temperature gradient and vertical velocity are confined at 700hPa and vertical circulation sloped north-westward with height .The strong cold advection downdraft in the rear of squall brought by the short wave disturbance at mid and low levels is an important mechanism for the development of the squall line.