台风“鲸鱼”对四川暴雨的远距离影响

The Long-distance Influence of Typhoon “Kujira” on the Heavy Rainfall in Sichuan

为了研究台风对四川暴雨的远距离影响,利用Micaps常规气象观测资料、四川省153站逐小时降雨资料以及FNL 1°×1°再分析资料,对2015年第8号台风"鲸鱼"登陆时的环流形势以及物理量场进行了详细分析。分析结果表明:(1)与台风与西南低涡相互作用可致川东南部地区暴雨不同,本次川东地区暴雨是台风"鲸鱼"与中高纬度短波槽以及西太平洋副热带高压相互作用的大尺度环流背景下,川东地区中尺度低涡系统造成的;(2)850 h Pa台风倒槽东侧的东南急流和700 h Pa副高西北侧的西南低空急流耦合,构成南海-四川的水汽通道,为暴雨的发生提供了充足的水汽。(3)500 h Pa西风槽与低层东南急流配合,输送正涡度,促进低层辐合,在川东地区形成中尺度低涡,同时台风不断向低涡中心提供气旋性涡度并与副高共同阻挡低涡的移动,使得低涡稳定维持,形成持续性暴雨。

To study the long-distance influence of typhoon ＂Kujira＂on the heavy rainfall in Sichuan province,conventional observation data,the hourly precipitation data of 153 stations in Sichuan and the FNL 1° ×1° 6 h reanalysis data are used to analyze the circulations and quantities when the 8 th typhoon ＂Kujira＂landed. The results show that：（1）Different with the interaction of typhoon with the southwest vortex,this heavy rainfall is caused under the background of short-wave trough in mid-high latitude together with the typhoon and west Pacific subtropical high（WPSH）.（2） The east flow of the inverted trough of typhoon closely connects with the low level southwest jet of WPSH,constituting the water vapor channel from the South China sea to Sichuan,which provides huge instability energy for the heavy rainfall.（3） The trough over the 500 h Pa interacted with the Southeast jet of the typhoon over the 850 h Pa,providing positive vorticity and convergence in the low level for the formation of the vortex. At the meantime,the typhoon and WPSH halts the movement of the vortex,which causes continuous rainstorm.