资源环境科技发展态势分析平台

A technique is developed to identify the types of atmosphere-ocean interaction during El Ni;o-Southern Oscillation events using sea surface temperature, sea level pressure (SLP), and outgoing longwave radiation (OLR) data. Two pairs of indices are derived that separate the interactions into tropical and subtropical types and basin-wide and local types. The dominant interaction type for the observed El Ni;o events since 1980 is identified and shown to shift with time from the tropical to subtropical and from basin-wide to local. Thus, the 21st century El Ni;os have become dominated by subtropical and local interactions, in strong contrast to the 20th century El Ni;os that were dominated by the tropical and basin-wide interactions. These changes result in the 1997?98 and 2015?16 extreme El Ni;os being different in their evolutions and global impacts, despite having similar intensities. SLP is the key variable for separating the tropical and subtropical types of interactions, while OLR is the key variable for separating the basin-wide and local types of interactions.