【摘要】 利用再分析资料及时间滤波方法,重点分析了低频环境场变化以及相关大尺度环境因子对台风强度突变的影响。结果表明:在"利奇马"强度突变前后,西北太平洋低频季风系统发展起了至关重要的作用,季风环流显著增强,西南季风东进,同时季风槽建立加强。这一现象为快速增强过程提供了水汽输送通道和理想的动力条件。西南季风增强使得台风南侧的水汽通道建立,同时季风槽发展有利于低层涡度的迅速积累,这些有利因子最终导致"利奇马"快速增强过程的发生。此外,弱的环境垂直风切变以及海表面温度的上升等因子同样对"利奇马"强度突变有重要影响。更多还原

【Abstract】 The RI process is analyzed in this study,and the most attention has been paid on the change of low-frequency environmental factors and their influences on the typhoon intensity changes. It is demonstrated that the development of the low-frequency monsoon system in the northwest Pacific played a crucial role before and after the sudden change in the intensity of typhoon "Lekima ",monsoonal circulation was developed and intensified during the RI over the western North Pacific,the southwestlies extended eastward and the monsoon trough was deepened. These phenomena provide moisture transportation and beneficial dynamical conditions. The enhancement of the monsoonal flows contributed to the ample moisture supply and the increase in low-level vorticity which played critical roles in the RI process. Besides,weak vertical wind shear and uprising sea surface temperature have important influences on the RI of "Lekima"as well.更多还原