대서양 허리케인 활동과 두 종류의 엘니뇨

Abstract

Recently, several studies have reported that there are two types of El Nino events, which are classified based on spatial patterns of sea-surface temperature (SST) anomaly. One is cold tongue (CT) El Nino, which can be regarded as the conventional El Nino, and the other is Warm Pool (WP) El Nino. The CT El Nino is characterized by relatively large SST anomalies in the NINO3 region, while the WP El Nino is associated with SST anomalies mostly confined to the NINO4 region. In addition, spatial patterns of many atmospheric and oceanic variables are also distinctively different for the two types of El Nino events. Due to their distinctiveness of the spatial structure, their teleconnection patterns are quite distinctive. In this study, their relationships with the Atlantic Hurricane Activity are investigated. It is well known that the Atlantic typhoon activity is weakened during the conventional El Nino (CT El Nino) period due to a strengthened vertical wind shear. However, we demonstrate here that there is clear difference of Atlantic Hurricane Activity during the WP El Nino period, compared to that of the CP El Nino. In particular, the number of Hurricane, which affect American continent, is significantly increased during WP El Nino events. It is demonstrated that this difference is linked to the shift of the teleconnection pattern.