Energetic connection between the South China Sea summer monsoon and Indian Ocean dipole from the perspective of perturbation potential energy

This study investigates the role of perturbation potential energy (PPE) in energetic connection between the South China Sea summer monsoon (SCSSM) and Indian Ocean dipole (IOD). When the SCSSM is strong during boreal summer, the higher and lower PPE anomalies controlled primarily by the diabatic heating correspond to negative and positive energy conversion, favoring the ascending and descending motions over western North Pacific (WNP) and southern Maritime Continent (SMC), respectively. This implies the existence of the regional Hadley circulation. This regional Hadley circulation-induced lower southeasterly wind anomalies reduce the local sea surface temperature (SST) anomalies over the tropical southeastern Indian Ocean via the wind-evaporation-SST and wind-thermocline-SST feedbacks, increasing the zonal SST gradient over the tropical Indian Ocean. Thus, a positive IOD event develops in boreal summer, and verse vice. Although the SCSSM decays during boreal autumn, the increased gradient of the PPE anomalies intensifies the anomalous Walker circulation over the tropical Indian Ocean, providing positive feedback that allows the IOD to mature. Consequently, the PPE dipole over WNP and SMC serves as an energetic bridge between the SCSSM and IOD.

Automated summary

This study explores the role of perturbation potential energy (PPE) in the energetic connection between the South China Sea summer monsoon (SCSSM) and Indian Ocean dipole (IOD). Strong SCSSM leads to positive/negative energy conversion and corresponding ascending/descending motions over the western North Pacific (WNP) and southern Maritime Continent (SMC), which indicates the existence of regional Hadley circulation. This circulation-induced wind anomalies reduce the local sea surface temperature over the tropical southeastern Indian Ocean, thus influencing the development of the IOD.