Modulation of Twin Tropical Cyclogenesis by the MJO Westerly Wind Burst during the Onset Period of 1997/98 ENSO
The modulation of twin tropical cyclogenesis in the Indian-western Pacific Oceans by the Madden-Julian Oscillation (M JO) during the onset period of 1997/98 ENSO is explored for the period of September 1996 to June 1997 based on daily OLR, NCEP/NCAR wind vector, and JTWC best track datasets. The M JO westerly wind burst associated with its eastward propagation can result in a series of tropical cyclogeneses in a multi-day interval. Only in the transition seasons are pairs of tropical cyclones observed in both the tropical sectors of the Indian-western Pacific Oceans. Two remarkable twin tropical cyclogeneses probably modulated by the M JO westerly wind burst are found: one is observed in the Indian Ocean in the middle of October 1996, and the other is observed in the Western Pacific Ocean in late May 1997. The twin tropical cyclogenesis in mid-October 1996 is observed when the super cloud cluster separates into two isolated clusters by the enhanced westerly wind, which is accompanied by two independent vortices in the equatorial tropical sectors. The other one, in late-May 1997, however, is characterized by one cyclonic flow that later results in another cyclonic cell in its opposite equatorial sector. Thus, there are two very important conditions for twin cyclogenesis: one is the M JO westerly wind straddling the equator, and the other is the integral super cloud cluster, which later splits into two cloud convective clusters with independent vortices.
作 者： 祝从文 Tetsuo Nakazawa 李建平 作者单位： 祝从文(Chinese Academy of Meteorological Sciences, Beijing 100081;LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029)Tetsuo Nakazawa(Meteorological Research Institute, Tsukuba, Japan 305-0051)
李建平(LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029)
刊 名： 大气科学进展(英文版) ISTIC SCI 英文刊名： ADVANCES IN ATMOSPHERIC SCIENCES 年，卷(期)： 2003 20(6) 分类号： 关键词： Madden-Julian oscillation westerly wind burst twin tropical cyclogenesis