Effect of the different stratification changes along the two sides of a typhoon track on near-inertial energy propagation

The β-effect and mesoscale vorticity are considered the two important mechanisms guiding the downward propagation of near-inertial energy (NIE), while the influence of stratification is often neglected. In this study, the “heat pumping” and “cold suction” effects of Typhoon Kalmaegi on ocean stratification were analyzed. Enhanced stratification accelerated the vertical propagation of near-inertial waves (NIWs) from the mixed layer into the ocean interior along the left side of the typhoon track. To illustrate the impact of stratification changes on both sides of typhoon tracks, the Regional Ocean Modeling System was used to simulate the NIWs generated by Typhoon Kalmaegi in 2014. The results show that, despite higher wind energy input along the right side of the typhoon track, the NIE injection into the deep ocean along the left side was stronger owing to reduced dissipation and enhanced stratification. This study improves our understanding of the generation, propagation, and dissipation mechanisms of wind-induced NIWs during typhoons.