西太平洋暖池1990s中期的年代际扩张对夏季登陆中国台风的影响

THE IMPACT OF INTERDECAL SHIFT OF THE WESTERN PACIFIC WARM POOL IN 1990S ON SUMMER TYPHOON LANDING IN CHINA COAST

应用美国联合预警中心(Joint Typhoon Warning Center,JTWC)的台风最佳路径资料、美国国家海洋大气局(National Oceanic and Atmospheric Administration,NOAA)的扩展海表面温度资料以及美国国家环境预报中心(National Centers for Environmental Prediction,NCEP)和美国国家大气科学研究中心(National Center for Atmospheric Research,NCAR)的大气环流场资料,研究了20世纪90年代西太平洋暖池(简称暖池)年代际扩张对西北太平洋台风和登陆中国沿岸台风的影响。研究发现,相比于暖池扩张前期(1965—1992),后期(1993—2013)台风生成在西北太平洋中部区域(10°—20°N,135°—145°E)显著减弱,在10°—20°N,145°—160°E区域和南海北部区域则表现出增多的特点。台风移动路径变异特征呈现为移动进入南海和登陆中国东部沿岸的西行和西北行路径减少,登陆日本的转向型路径增多,同时登陆我国海南岛和东南部沿岸的台风增多。进一步探查这种影响的可能原因发现,与暖池扩张密切相关的太平洋年代际变化引起的纬向环流的变异是西北太平洋中部台风生成减少的主要原因;而南海北部台风生成增多则归因于南海区域局地环流特征的变异。同时,南海北部台风生成增多是登陆我国海南岛和东南沿岸台风增多的主要决定因素。

The impact of the shift of the western Pacific warm pool（WPWP） in 1990 s on typhoon genesis in the northwestern Pacific（NWP） in the summer（July—September） was studied based on the best typhoon track data from the U.S. Joint Typhoon Warning Center（JTWC）, the extended sea-surface temperature from NOAA, and the atmospheric circulation data from NCEP/NCAR. The results show that in the post-period of the WPWP shift, typhoon genesis would be suppressed in the central region of 10°—20°N, 130°—145°E, but enhanced in the more eastern region of 10°—20°N, 145°—160°E, of the South China Sea（SCS）. Typhoons entering the SCS or eastern coasts of China was decreased, while those that turned towards Japan or Hainan Island or southeastern coasts of China increased. In addition, we found that the suppressed typhoons genesis in the central region of NWP was related to the change of latitudinal circulation caused by the Interdecadal Pacific oscillation, which has close relationship with the WPWP shift in the 1990 s. On the other hand, typhoons genesis in the northern SCS is associated with the change of local circulation. Therefore, typhoon genesis increase in the northern SCS is the main reason of typhoon landing increase in the Hainan Island and southeastern coastal regions of China.