Modulation of Northwest Pacific Tropical Cyclone Genesis by the Intraseasonal Variability

Journal of the Meteorological Society of Japan. Ser. II

Haikun ZHAO¹  Liguang WU¹  Xianan JIANG² 

[1] Pacific Typhoon Research Center, Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science and Technology, Nanjing, China;Joint Institute for Region Earth System Science & Engineering, University of California, Los Angeles, U.S.A.

关键词: intraseasonal variability;    Madden-Julian oscillation;    quasi-biweekly oscillation;    tropical cyclone genesis;    western North Pacific;   

DOI  :  10.2151/jmsj.2015-006

学科分类：大气科学

来源: Meteorological Society of Japan

【 摘 要 】

 The modulation of tropical cyclone (TC) genesis over the western North Pacific (WNP) by the intraseasonal variability (ISV) is investigated in this study. The two leading ISV modes, i.e., the 40-day Madden-Julian oscillation (MJO) and the 16-day quasi-biweekly oscillation, are found to exert significant impacts on TC genesis over the WNP. A majority of TC geneses over the WNP is found to occur during the period when both the modes are active, suggesting a joint influence of the two modes on TC genesis over the WNP.  The modulation of TC genesis over the WNP by the two leading ISV modes can be well depicted by the genesis potential index (GPI). Contributions of the four terms to the total GPI anomalies are further analyzed to determine the key factors involved in modulations of TC genesis by both of the ISV modes. Results indicate that while, in general, the low-level absolute vorticity and the mid-level relative humidity are the two most important factors affecting WNP TC genesis, relative roles of the four GPI factors also tend to be dependent on the ISV phases. This study provides further understanding of the ISV modulation of WNP TC genesis, which could benefit the intraseasonal prediction of the TC activity.

【 授权许可】

Unknown