Program

Analysis 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 interannual time scale, the resurfacing of South Pacific Tropical Water acts to modulate the sea surface salinity at a rate equivalent to about 25% of the surface freshwater flux. The results suggest that the resurfacing of South Pacific Tropical Water contributes to the sea surface salinity variability in the equatorial Pacific and plays a potentially important role in ENSO evolution.