Distinguished Effects of Interannual Salinity Variability on the Development of the Central-Pacific El Niñ Events

Abstract

AbstractEl Nino events in the central equatorial Pacific (CP) are gaining increased attention, due to their increasing intensity within the global warming context. Various physical processes have been identified in the climate system that can be responsible for the modulation of El Nino, especially the effects of interannual salinity variability. In this work, a comprehensive data analysis is performed to illustrate the effects of interannual salinity variability using surface and subsurface salinity fields from the Met Office ENSEMBLES (EN3) quality controlled ocean dataset. It is demonstrated that during the developing phase of an El Nino event, a negative sea surface salinity (SSS) anomaly in the western-central basin acts to freshen the mixed layer (ML), decrease oceanic density in the upper ocean, and stabilize the upper layers. These related oceanic processes tend to reduce the vertical mixing and entrainment of subsurface water at the base of the ML, which further enhances the warm sea surface temp...