A hybrid coupled model for the tropical Pacific constructed by integrating ROMS with a statistical atmospheric model

Numerical models are crucial for quantifying the ocean-atmosphere interactions associated with the El Niño-Southern Oscillation (ENSO) phenomenon in the tropical Pacific. Current coupled models often exhibit significant biases and inter-model differences in simulating ENSO, underscoring the need for alternative modeling approaches. The Regional Ocean Modeling System (ROMS) is a sophisticated ocean model widely used for regional studies and has been coupled with various atmospheric models. However, its application in simulating ENSO processes on a basin scale in the tropical Pacific has not been explored. For the first time, this study presents the development of a basin-scale hybrid coupled model (HCM) for the tropical Pacific, integrating ROMS with a statistical atmospheric model that captures the interannual relationships between sea surface temperature (SST) and wind stress anomalies. The HCM is evaluated for its capability to simulate the annual mean, seasonal, and interannual variations of the oceanic state in the tropical Pacific. Results demonstrate that the model effectively reproduces the ENSO cycle, with a dominant oscillation period of approximately two years. The ROMS-based HCM developed here offers an efficient and robust tool for investigating climate variability in the tropical Pacific.