Relation between ENSO and tropical cyclones in the WNP simulated in a CGCM

We investigated the relation between ENSO and frequency of tropical cyclones in the western North Pacific simulated in a high-resolution coupled general circulation model. During the 100 year integrations, the model simulates the ENSO-like events with the period of 4-5 years and with the larger amplitude in Nino3 sea surface temperature (SST) anomalies than the observations. In the El Nino (La Nina) years, the annual frequency of the model tropical cyclones in the southeastern quadrant of the western North Pacific increases (decreases), while it decreases (increases) in the northwestern quadrant (Fig. 1), as in observations. In spite of the significant difference in the mean genesis locations of model tropical cyclones between El Nino and La Nina years, however, there is no significant difference in the annual frequency of model tropical cyclones in both El Nino and La Nina years. The annual frequency of model tropical cyclones, on the other hand, tends to decrease (increase) in the following El Nino (La Nina) years, relating to the development of anticyclonic (cyclonic) circulation in the Philippine Sea in response to the SST anomalies in the central and eastern equatorial Pacific (Fig. 2).