Diagnostic Method for Atmosphere-Ocean Coupling Over Tropical Oceans at the Sub-Seasonal Timescale

This study introduces a novel diagnostic method to assess tropical atmosphere-ocean coupling, using a two-dimensional plane defined by the 90-day high-pass-filtered sea surface temperature (SST) and column water vapor (CWV). The method was applied to reanalysis data and high-resolution coupled atmosphere-ocean simulation data. In the Indo-Pacific warm pool region, the phase relationship between SST and CWV remained consistent across both reanalysis and simulation data sets. However, differences in the temporal evolution of these variables were observed in the central Pacific region. The heat budget analysis results indicate that the differences between the two data sets in the central Pacific are related to variations in the effects of atmospheric disturbances on SST. This study demonstrates the potential of our novel diagnostic method for evaluating atmosphere-ocean coupling in climate models. Weather disturbances in the tropics develop from the interaction between the ocean and the atmosphere. We can use climate models to investigate the impact of this interaction, but we need other methods to evaluate the interaction itself. In this study, we develop a new way to understand how the atmosphere and the ocean interact in the tropics. We achieve this by focusing on changes over time in the sea surface temperature and the amount of water vapor in the air. We found that these changes happen at different rates in different regions of the ocean. We also found that a climate model failed to capture these changes in some regions. Our new method improves our understanding of the atmosphere and ocean interaction and teaches us how to improve climate models. A novel analysis method was developed to illustrate regional differences in the atmosphere-ocean coupling across tropical oceans The application of this diagnostic method to the reanalysis and coupled model data revealed differences in the central Pacific region Through heat budget analysis, we proposed distinct processes by which atmospheric disturbances change the sea surface temperatures