Mechanistic challenges of prolonged ENSO events in CMIP6 climate models: an analysis

Abstract

The study delves into the complexities of prolonged El Niño (PE) and La Niña (PL) events, examining their behaviour, dynamics, and representation in climate models participating in CMIP6. These events deviate from the typical cycles of the El Niño-Southern Oscillation (ENSO) system and significantly impact global weather patterns and socioeconomic systems. The study aims to enhance our understanding of these multi-year ENSO events through a comparative analysis of observational data and model simulations. Observational data reveal the distinct characteristics of PE and PL events, with prolonged warming or cooling anomalies persisting in the equatorial Pacific beyond the usual timeframe associated with canonical El Niño (CE) and La Niña (CL) events. However, while climate models generally capture the general trend of sustained warming or cooling, discrepancies exist in the magnitude and timing of SST anomalies, particularly during peak phases. The analysis highlights limitations in the ability of current climate models to simulate consecutive El Niño events following PE events and strong El Niño events preceding PL events accurately. Furthermore, discrepancies in the representation of subsurface oceanic dynamics and zonal wind stress patterns underscore challenges in capturing the intricate interactions driving ENSO variability. The study emphasizes the importance of refining climate models to capture better the intricacies of prolonged ENSO events, which have significant implications for future climate projections and adaptation strategies.