近160年西北太平洋副高的年代际变化及其对台风年际变化的影响

INTERDECADAL VARIATION OF THE WEST PACIFIC SUBTROPICAL HIGH AND ITS INFLUENCE ON THE VARIATION OF TYOHOONS IN RECENT 160 YEARS

研究着眼于上百年尺度西太副高及台风活动变化特征,通过统计分析的方法对百年来台风活动特性及其与西太副高的相关性进行分析。结果表明:(1)近160a副热带高压的范围增大、强度增强,在1980年前后,副高平均北界明显北抬,西脊点明显西伸,这种变化与经向环流(Hadley环流)和纬向环流(Walker环流)的变化相关,Hadley环流下沉支(wh)对西太副高关键区的副高强度(h)存在正影响,Walker环流上升支(ww)则存在负影响;(2)各区域1930年后台风影响时长和年频数均增加。而1975—2020年时段西北太平洋台风年平均影响时长与1930—1975年时段相比有所下降,但发生年频率无明显变化;华南地区的年影响时长与年频数没有明显变化,但我国华东沿海地区台风的年影响平均时长与年频数均显著增加。Hadley环流下沉支、Walker环流上升支、副高强度与西北太平洋台风活动范围向西向北伸展及各区域发生频率显著相关,具有一定的指示意义。

The study focuses on the change of typhoons on the scale of century,analyzes the influence of the West Pacific subtropical high on typhoon activity in recent 160 years,and analyzes the reasons for the change in typhoon activity characteristics in the past years by using statistical methods.The results show that:(1)The range and intensity of the subtropical high have increased in recent 160 years.After 1980,the average northern boundary of the subtropical high has obviously raised northward,and the western ridge point has obviously extended westward.This is related to the changes of the meridional and latitudinal circulation.The sinking part of Hadley circulation(wh)has a positive influence on the intensity(h)of the West Pacific subtropical high,but the raising part of Walker circulation(ww)has negative influence.(2)After 1930,the duration and annual frequency of typhoons’activities in the Northwest Pacific increased.Compared with 1930—1975,the annual average duration of typhoons’activities in the Northwest Pacific during 1975—2020 decreased,but the annual frequency did not change significantly.There is no obvious change in the annual impact duration and frequency in South China,while the average duration and frequency of typhoons’activities in East China increased significantly.The three factors wh,ww,and h are significantly related to the westward and northward extension of typhoons’activities in the Northwest Pacific and the frequency of each region.