Although it is well known that the tropical easterly jet (TEJ) has a significant impact on summer weather and climate over India and Africa, whether the TEJ exerts an important impact on tropical cyclone (TC) activity over the western North Pacific (WNP) remains unknown. In this study, we examined the impact of the TEJ on the interannual variability of TC genesis frequency over the WNP in the TC season (June-September) during 1980-2020. The results show a significant positive correlation between TC genesis frequency over the WNP and the jet intensity in the entrance region of the TEJ over the tropical western Pacific (in brief WP_TEJ), with a correlation coefficient as high as 0.66. The intensified WP_TEJ results in strong ageostrophic northerly winds in the entrance region and thus upper-level divergence to the north of the jet axis over the main TC genesis region in the WNP. This would lead to an increase in upward motion in the troposphere with enhanced low-level convergence, which are the most important factors to the increases in low-level vorticity, mid-level humidity and low-level eddy kinetic energy, and the decreases in sea level pressure and vertical wind shear in the region. All these changes are favorable for TC genesis over the WNP and vice versa. Further analyses indicate that the interannual variability of the WP_TEJ intensity is likely to be linked to the local diabatic heating over the Indian Ocean-western Pacific and the central Pacific El Ni?o-Southern Oscillation.

Ruifen ZHAN;Yuqing WANG;Yihui DING

Department of Atmospheric and Ocean Sciences,Institute of Atmospheric Sciences,Fudan University,Shanghai 200438,China;Shanghai Typhoon Institute of China Meteorological Administration,Shanghai 200030,China;Innovation Center of Ocean and Atmosphere System,Zhuhai Fudan Innovation Research Institute,Zhuhai 519055,China;International Pacific Research Center and Department of Atmospheric Sciences,School of Ocean and Earth Science and Technology,University of Hawaii at Manoa,Honolulu,Hawaii,HI 96822,USA;National Climate Center and Laboratory for Climate Studies,China Meteorological Administration,Beijing 100081,China

大气科学进展（英文版）

[1]Ruifen ZHAN;Yuqing WANG;Yihui DING-.Impact of the Western Pacific Tropical Easterly Jet on Tropical Cyclone Genesis Frequency over the Western North Pacific)[J].大气科学进展（英文版）,2022(02):235-248

Easterly,TEJ,ageostrophic

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