Abstract
Despite their pronounced climate impacts, the physical processes that control the frequency of multiyear El Ni & ntilde;o events remain incompletely understood. Using an Interactive Ensemble (IE) coupling strategy, we find that atmospheric noise forcing plays an important role in modulating the frequency of multiyear El Ni & ntilde;o events. When thermocline-related stochastic forcing is stronger, equatorial warm-water volume is less effectively discharged after the first El Ni & ntilde;o peak, increasing the likelihood that positive recharge persists into the following year. Sensitivity experiments with the Stochastic Recharge Oscillator model show that a larger diagnosed (the amplitude of wind-stress-driven atmospheric noise forcing on thermocline-depth anomalies) is systematically associated with a higher frequency of multiyear El Ni & ntilde;o events. These results reveal a previously underrecognized pathway through which stochastic atmospheric variability modulates the persistence of El Ni & ntilde;o events.