Feedback of tropical cyclones on El Nino diversity. Part I: Phenomenon

Understanding of the El Nino phenomenon is improving and several studies have considered the dynamics of El Nino diversity, however, the important role of tropical cyclones has rarely been reported. Here we show a clear feedback of tropical cyclones (TCs) over the western North Pacific (WNP) on the El Nino diversity. Strong (weak) accumulated cyclone energy helps to shift the center of strongest sea surface temperature anomalies 3 months later to the equatorial eastern (central) Pacific, and thus supporting the development of the eastern-Pacific (central-Pacific) El Nino. Local sea surface temperature anomalies in the Nino-3.4/Nino-3/Nino-4 region and tropical western Pacific, zonal wind anomalies over the tropical central-western Pacific and Madden-Julian Oscillation play small roles in the process that WNP TCs affect El Nino diversity. Moreover, the greater number of central-Pacific El Nino events after 1999/2000 may be associated with weaker accumulated cyclone energy in this period.