北上台风时空变化特征及其与ENSO的关系

Spacio-Temporal Variation Characteristics of Northward-Moving Typhoon and Their Relationship with ENSO

基于中国气象局热带气旋最佳路径数据集,对1949—2022年北上台风的时空变化特征进行统计分析,并探讨了厄尔尼诺-南方涛动(El Niño-Southern Oscillation,ENSO)对北上台风活动的影响。结果表明:1)74年间共有275个北上台风活动,频数的年际变化呈不显著上升趋势,但北上台风占西北太平洋生成台风总数的比例呈现显著的上升趋势;2)北上台风主要集中在7—9月生成,8月份进入定义区数量最多,生命期强度以超强台风、台风等高强度等级居多,且高强度等级北上台风出现的几率近些年有增加趋势;3)共有159个北上台风在中国登陆,未登陆转向路径台风大多在30°N、125°―130°E附近向东转向。北上台风生成位置大多集中在10°―20°N、130°―150°E,登陆类北上台风的生成位置更加偏西,消散类台风的生成位置纬度更高;4)Niño 3.4指数与北上台风频数和生命期强度分别呈显著的负相关和正相关关系,同时其对北上台风的生成位置也具有明显影响。与厄尔尼诺年相比,拉尼娜年生成的北上台风数量更多,生成位置更加偏西、偏北,但厄尔尼诺年发生的北上台风强度更高。

Social and economic losses from typhoons are increasing owing to climate change.It is of practical significance to correctly understand new characteristics and trends in typhoon activity.Based on the best track dataset of tropical cyclones from the China Meteorological Administration,the temporal and spatial variation characteristics and evolution law of northward-moving typhoons from 1949 to 2022 were analyzed using the linear trend,Mann-Kendall test,and wavelet analysis method,and the impacts of the El Niño-Southern Oscillation(ENSO)on typhoon activities were also discussed.The results showed that:(1)275 northwardmoving typhoons occurred during the past 74 years,with an average of 3.7 per year.The interannual fluctuation in typhoon frequency was large,and the upward trend was not significant.The proportion of northward-moving typhoons to the total number of generated typhoons in the Northwest Pacific was between 2%and 30%,showing a significant upward trend.(2)Northward-moving typhoons were mainly generated from July to September,accounting for approximately 88.4%of the total typhoons.The highest number of typhoons entering the defined area was 114 in August.The life-cycle intensity of northward-moving typhoons is dominated by high-intensity grades,such as super typhoons and typhoons.Among them,super-typhoons accounted for 30.5%of the total number of northward-moving typhoons,and the intensity of typhoons and above grades exceeded 70%of the total amount.In recent years,the probability of high-intensity northward-moving typhoons has increased.(3)A total of 159 northward-moving typhoons landed in China over 74 years.Most of the turning-track typhoons made landfall in Taiwan,Fujian,and Zhejiang,whereas the landing locations of landed disappearing-track typhoons made landfall more northerly.Most unlanded turning-track typhoons turned eastward near 30°N and 125–130°E,showing a significant upward trend.The generating positions of the northward-moving typhoons were mainly concentrated in the ranges of 10—20°N and 130—150°E,with a density of 4.65/10,000 km2.The central generation position of the landed northward-moving typhoons was 4.2°more westward than that of the unlanded typhoons.The latitude of the central generating position of the disappearing typhoons was 2.1°northward compared to that of the turning typhoons.(4)The Niño3.4 index had significant negative and positive correlations with the frequency and life-cycle intensity of northward-moving typhoons,respectively,and it also had an obvious effect on their generating positions.There were 4.5 northward-moving typhoons in the La Niña year,which was 1.67 times the El Niño year.However,the intensity of northward-moving typhoons generated during El Niño years was significantly higher than that generated during La Niña years,and the intensity of northwardmoving typhoons increased with the Niño3.4 index.The central generating position of northward-moving typhoons during La Niña years was 5.8°northward and 12.4°westward compared to that during El Niño years,which was closer to China.This study provides a basis and reference for strengthening the risk management of typhoons and improving the efficiency of disaster prevention and reduction.