垂直风切变对螺旋波不稳定的影响

通过建立一系列局地准二维直角坐标系,用以研究垂直风切变对热带气旋中螺旋波不稳定的影响,并计算了螺旋波不稳定增长率在螺旋线上的分布,得到了以下结论:不稳定增长率开始随热带气旋半径增大而增大,在最大风速圈处达最大;然后随半径减小,以后再随半径增大,出现一个局地极值,再以后又减小,即在螺旋线上有两个极值中心;这与实际热带气旋的情况相一致。不稳定螺旋波的增长率与基流的垂直切变和层结参数密切有关,基流垂直切变越大,层结参数越小,则增长率越大;也即Richardson数越小,则不稳定增长率越大。

The impact of vertical wind shear on spiral wave instability

In this paper we use a series of local quasi-two-dimensional Cartesian coordinates to study the impact of vertical wind shear on spiral wave instability in tropical cyclones,and calculate the distribution of the growth rate of spiral wave instability on the spiral line. The conclusions are as follows: at the beginning,the growth rate of instability increases as the tropical cyclone radius extends,and became the largest on the maximum wind-speed circle; then it decreases later and goes up again when it gets ...