基于蓝金模式下的中气旋与龙卷雷达回波模拟

Simulation of Radar Echo from Mesocyclones and Tornadoes based on Rankine Model

中气旋是强对流灾害性天气发生的特征,其形成过程分为生成阶段、成熟阶段和消亡阶段,处于成熟阶段的中气旋在4个不同高度层上具有不同的速度特征.强烈的中气旋或扩展到地面附近的中等以上强度的中气旋产生龙卷的概率约为40%.绝大多数龙卷发生于中气旋核区内,但并不是所有的中气旋都能发展成龙卷.多普勒天气雷达是探测中气旋与龙卷的射频传感器,但可用的中气旋与龙卷的回波数据有限,对中气旋与龙卷展开数值模拟是一种可供选择的方法.本文首先利用蓝金模式模拟出中气旋的风场和中气旋核区内发生龙卷时的风场.然后使用多普勒雷达对该风场进行探测,生成中气旋与龙卷回波数据,并显示出多普勒雷达径向速度图.生成的回波数据可用于中气旋与龙卷识别算法的验证.

In the formation process of a mesocyclone that is the features of hazardous convective weather can be divided into three stages: generation stage, maturity stage and extinction stage. A mesocyclone in maturity stage has diverse velocity characteristics at four different altitudes. The probability of a tornado occurring in a strong mesocyclone or a mesocyclone with moderate or higher intensity extending near the ground is about 40%. Multiple tornadoes occur in the center of mesocyclones, but not all of the mesocyclones can develop into tornadoes. Doppler weather radar is a kind of radio-frequency sensor that can detect mesocyclones and tornadoes, but the amount of echo data available to apply is limited, so the numerical simulation of mesocyclones and tornadoes is an alternative. In this paper, the wind field of mesocyclone and tornado in the center of mesocyclone are initially simulated by Rankine model. Then the mesocyclone and tornado echo data can be generated and then display the Doppler radar velocity image after the wind fields are sounded by Doppler radar. The generated echo data generated can be applied to the verification of mesocyclones and tornadoes identification algorithm.