Resurfacing of South Pacific Tropical Water in the Equatorial Pacific and Its Variability Associated with ENSO

Abstract

nalysis of results from a simulated passive tracer confirms the resurfacing of South Pacific Tropical Water in the equatorial Pacific. Over the period of integration (1993?2011), both the volume and barycenter of the South Pacific Tropical Water that resurfaces in the equatorial Pacific are tightly linked to El Niño?Southern Oscillation (ENSO), with their correlation with the Niño-3.4 index reaching ?0.79 and 0.84, respectively. Their correlation (?0.75 and 0.85) with the sea surface salinity index, Niño-S34.8, is also high. Of particular interest is that both the volume and barycenter of the resurfacing South Pacific Tropical Water peak earlier than the ENSO indices by about 3 months. On the interannual time scale, the resurfacing of South Pacific Tropical Water may modulate the sea surface salinity in the equatorial Pacific at a rate equivalent to as much as 25% of the surface freshwater flux. The results suggest that the resurfacing of South Pacific Tropical Water directly contributes to the sea surface salinity variability in the equatorial Pacific and potentially plays a role in ENSO evolution.