Impacts of Two Types of El Niño and La Niña Events on Typhoon Activity

The HadISST (Hadley Centre Sea Ice and Sea Surface Temperature) dataset is used to define the years of El Nino, El Nino Modoki, and La Nina events and to find out the impacts of these events on typhoon activity. The results show that the formation positions of typhoon are farther eastward moving in El Nino years than in La Nina years and much further eastward in El Nino Modoki years. The lifetime and the distance of movement are longer, and the intensity of typhoons is stronger in El Nino and in El Nino Modoki years than in La Nina years. The Accumulated Cyclone Energy of typhoon is highly correlated with the Oceanic Nino Index with a correlation coefficient of 0.79. We also find that the typhoons anomalously decrease during El Nino years but increase during El Nino Modoki years. Besides, there are two types of El Nino Modoki, I and II. The intensity of typhoon in El Nino Modoki I years is stronger than in El Nino Modoki II years. Furthermore, the centroid position of the Western Pacific Warm Pool is strongly related to the area of typhoon formation with a correlation coefficient of 0.95.