El Niño and La Niña asymmetry in short-term predictability on springtime initial condition

Abstract El Niño-Southern Oscillation (ENSO) asymmetry in predictability on springtime initial condition remains unclear. From the perspective of spring barrier (SPB), this paper investigates ENSO SPB and explores potential factors that may lead to asymmetry. Both observation 29 Coupled Model Intercomparison Project Phase 6 (CMIP6) models show sea surface temperature (SST) persistence is significantly higher Niño years than La Niña years, intensity stronger years. Through recharge oscillator model, CMIP6 models, we demonstrate nonlinear wind stress response SST anomalies main cause asymmetric intensity. By mixed-layer heat budget tropical Pacific spring, further identify a zonal events can advection feedback, which finally leads weaker enhances Niño. In contrast, cooling only weak easterly anomalies, feedback relatively weaker, thus lower. SPB, suggest more predictable Niña.