A Better Understanding of ENSO-Related Tropical Cyclone Activity in French Polynesia

The El Niño Southern Oscillation (ENSO) is the dominant mode of climate variability on a global scale. El Niño and La Niña events disrupt atmospheric and oceanic conditions in the Pacific Ocean as well as globally through teleconnections. A large diversity is observed from one event to another, leading to the concept of an "ENSO continuum", making it difficult to predict their impacts. Here we will focus on the South Central Pacific and French Polynesian archipelagos, which are spread across an area as vast as Europe and have received limited attention. We show that considering more diversity than the classical EP/CP approach is needed to fully understand climate impacts and tropical cyclone (TC) activity in French Polynesia. The extreme eastern Pacific El Niño events of 1982/1983 and 1997/1998, with record-breaking TC activities, clearly stand out from other events, particularly from the 2015/2016 extreme event (with no TCs). Large scale environmental factors involved in the cyclogenesis such as precipitation and wind, exhibit diverse characteristics depending on the ENSO event. We quantify their influences thanks to different cyclogenesis indices to identify the underlying mechanisms. It appears that strong eastern pacific El Niño We will finally discuss our results in view of the 2023/2024 cyclonic season associated with strong El Niño conditions.