1804号台风“艾云尼”引发的广州两段强降水分析

Comparison and Analysis of Two Intense Rains in Guangzhou Induced by Typhoon Ewiniar(1804)

1804号台风“艾云尼”给广州带来了近10年最强的台风降水,对期间主要出现的两次强度明显不同的强降水过程的成因进行了对比分析,结果表明:(1)第1段强降水主要是受“艾云尼”外围环流影响,第2段转受其本体环流影响,深厚的低空急流为强降水的产生提供了较好的水汽和不稳定能量条件;(2)第2段强降水过程高低空辐散辐合强度均增大到第1段过程的1.5倍以上,为第2段强降水的增强提供了更好的动力条件;(3)第2段强降水过程水汽通量及辐合强度较第1段明显增强,为降水的增强提供了更好的水汽条件;(4)强的θ_(se)平流输送及其随高度的减弱是不稳定能量维持的重要原因。

Typhoon Ewiniar(1804)brought Guangzhou the most intense typhoon-related rain the city has ever seen in the past ten years.This paper compares and analyzes the causation of two intense rains with the storm’s visit that are significantly different in intensity.The result is shown as follows.(1)The first intense rain mainly resulted from the circulation at the periphery of Ewiniar while the second one came under the control of the storm’s bulk circulation so that deep low-level jet streams supplied good conditions of water vapor and instability energy for the generation of the intense rain.(2)In the second intense rain,the upperlevel divergence and low-level convergence are more than 1.5 times as strong as in the second one,providing better dynamic conditions for the enhancement of intense rain.(3)For water vapor flux and convergence intensity,the second intense rain is much larger than the first one,making good water vapor conditions for the intensification of rain.(4)The transportation of a strongθ_(se) advection and its reduction with altitude are mainly responsible for the maintenance of instability energy.