0418号“艾利”台风暴雨过程的数值模拟

Numerical simulation of typhoon "Aere"(No.0418) rainstorm

本文利用中尺度MM5模式模拟了0418号“艾利”台风造成闽东北强降水的一次物理过程.模拟结果表明:充沛的水汽和强烈的上升运动是造成台风暴雨的直接原因,降水与850hPa涡度场、散度场有较好的对应关系.基本流场存在二次切变时,横波型扰动会激发产生并且发生不稳定,从而导致暴雨天气的产生.台风附近相当位温密集陡峭和CAPE值的突增表明台风有加强的可能,CISK和涡旋Rossby波的传播是可能的机制.水汽的敏感性试验结果表明:水汽变化会影响台风的强度和降水的强度,水汽的微小变化可造成降水极大的变化,但对台风的位置影响不大.

A physical courses of heavy rain in the northeast of Fujian Province caused by typhoon ＂Acre＂ （No. 0418） is simulated using the PSU/NCAR model MM5. It is found that moisture and strong ascending motion produced typhoon rainstorm directly and the rainstorm has a close relation to vorticity,divergence at 850hPa. Transverse-wave disturb（vortex Rossby-savespropagation mainly） can be exploded and atmosphere became instability when there were two shear along the basic flow field. The craggedness and denseness of equivalent potential temperature（ETH） and the strength of CAPE may indicate the possibility of typhoon strengthen which can be explained by CISK and vortex Rossby-savespropagation. The sensitivity experiments showed that changes in water vapor had a sig- nificant effect on the rainstorm, the position and pressure of the typhoon center, but their influence are different. The little changes in water vapor would greatly influence the rainstorm, but water vapor variety caused little effect on the position of typhoon.