The role of Pacific Tropical Instability Wave in Sub-Seasonal SST predictability

Tropical Instability Waves (TIWs) play a crucial role in modulating Sea Surface Temperature (SST) variability in tropical oceans, yet their representation in current forecast systems remains challenging. This study investigates the relationship between TIWs and sub-seasonal SST predictability while evaluating the performance limitations of the Licoms Forecast System. Through comprehensive analysis of observational data and model outputs, we demonstrate that TIWs provide significant potential for enhancing sub-seasonal SST forecast skill through their regular wave patterns and predictable evolution characteristics. However, our findings reveal that the current Licoms forecast systems systematically underestimate both TIW intensity and wavelength. Critical examination of error sources indicates that these deficiencies primarily originate from initialization fields rather than model physics or dynamics.