Changes in the zonal propagation of El Niño-related SST

Abstract

Long-term variability of El Niño (EN) cycle has been the topic of several studies, mainly because of its impacts on climate around the globe. This variability has been mainly described by changes in the intensity and frequency of EN events. In this study, interdecadal changes in the zonal evolution of EN-related sea surface temperature anomalies (SSTA) and their possible link with a well known mode of Pacific interdecadal variability are analyzed. EN events are classified according to the sense of zonal propagation of SSTA along the equatorial Pacific during the period 1900?2012. As a result, two types of EN are defined: Eastward-directed and Westward-directed EN. It is found that EN-related SSTA preferably evolve to the east (west) during the warm (cold) phase of thePacific Decadal Oscillation. Hence, this study offers new insights into the possible causes of long-term EN changes.