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Keywords:

  • ENSO;
  • ocean–atmosphere interaction;
  • recharge-discharge oscillator;
  • Southern Ocean freshening;
  • thermocline adjustment

Abstract

The response of El Niño-Southern Oscillation (ENSO) to idealized freshwater forcing over the Southern Ocean (SO) is investigated using a fully-coupled climate model. Modeling results explicitly show that freshening over the SO can modulate mean climate of tropical Pacific, triggering La Niña-like sea surface temperature (SST) anomalies and a sharper zonal tilt of tropical thermocline, which further influences ENSO variability. Amplitude of ENSO is intensified due to shallower thermocline in central-eastern tropical Pacific, while the period of ENSO is significantly enlarged primarily because upper-ocean meridional temperature gradient between equatorial and off-equatorial region is decreased, which is favorable to extend the period of ENSO © 2012 Royal Meteorological Society.