Assessment of the modulation by the small-scale variability on the eastern edge of the equatorial Western Pacific Warm Pool

El Nino and its cold counterpart La Nina, together referred to as the ENSO variability, represent the strongest year-to-year climate fluctuation on the planet. While there has been a gradual improvement in model ENSO prediction skill, there have been failures and successes during the most recent years that remind us that ENSO remains one of the most compelling problems in climate research. ENSO variability is generated primarily by coupled ocean-atmosphere instability near the eastern edge of the equatorial Western Pacific Warm Pool. Although it is not well defined by the SST, the eastern edge of the WPWP can be located by the convergence of zonal currents and by a well-defined salinity front that is trapped on the equator. Nevertheless, the separation of the WPWP from the eastern-central cold tongue is a complex phenomenon that will require an analysis of a combination of several parameters to achieve a full understanding. The observations collected during a set of three oceanographic cruises to the frontal zone are part of a study dedicated to advancing that understanding by analyzing the underlying physical processes that are at the root of the frontal formation and variability. These cruises have shown that the salinity front cannot necessarily be observed at the surface. This study will explore the possibility that small-scale features, such as those recently documented in the Coral Sea which varied about +/-1 unit in SSS and which were associated with mixing and stirring by mesoscale eddies, could play a similar role on the equator. Looking beyond how these small-scale features could blur the eastern edge of the equatorial warm pool, we will also discuss the possible effect of this variability on the biogeochemistry and biologic fields of the region