Study of the relationship between the East Asian marginal SST and the two different types of El Niño

Abstract

In this study we define the two different types of El Niño, i.e., the eastern Pacific El Niño (i.e., EP-El Niño) versus the central Pacific El Niño (i.e., CP-El Niño), during the boreal summer (June-July-August, JJA) and winter (December-January-February, DJF) using the two NINO indices in the tropical Pacific. The two different types of El Niño significantly differ in terms of the location of the maximum anomalous sea surface temperature (SST) in the tropical Pacific. The CP-El Niño has been observed more frequently during recent decades compared to the EP-El Niño. In addition, our analysis indicates that the statistics of CP-El Niño during JJA is closely associated with the warming trend in the central equatorial Pacific. We also examine the different responses of the East Asian marginal SST to the two types of El Niño during JJA and DJF. The CP-El Niño during both JJA and DJF is concurrent with warm SST anomalies around the Korean Peninsula including the East China Sea, which is in contrast to the EP-El Niño. Such different responses are associated with the difference in tropics/mid-latitude teleconnections via atmosphere between the two types of El Niño. Furthermore, our results indicate that atmospheric diabatic forcing in relation to the precipitation variability is different in the tropical Pacific between the EP-El Niño and the CP-El Niño.