The similarity between the seasonal Predictability and Persistence Barrier of ENSO phenomenon

The seasonal Predictability Barrier (PRB) and Persistence Barrier (PEB) in the El Niño-Southern Oscillation (ENSO) phenomenon are of recent interest, yet the distinction between the PRB in observations and PEB in ensemble forecast models remains unexplored. Using observational and North American Multimodel Ensemble data since the 1980s, we examined the seasonal PRB and PEB, focusing on intensity, timing, decadal variations, and spatial patterns. Although the intensity of the ENSO spring PRB in dynamic models is notably lower than the spring PEB intensity, the temporal variations, spatial patterns and barrier timing of the PRB and PEB are similar. The chaotic nature of ENSO systems exhibits comparable decadal variations and spatial patterns to the seasonal PEB and PRB, suggesting potential control by chaotic behavior for both seasonal PRB and PEB. Hence, the seasonal PEB of ENSO can still provide useful benchmarks for the predictability study of ENSO in dynamic models.