南太平洋上层海洋对热带气旋“哈罗德”(2020)的响应特征分析

Tropical cyclones are intense, nonlinear atmospheric eddies that form over the ocean and can induce complex and violent oceanic dynamics as well as thermal responses in the upper ocean. In 2020, Super Tropical Cyclone Harold developed over the tropical South Pacific Ocean, reaching maximum wind speeds of 64.3m/s. Following its formation, Harold exhibited an unusual west-to-east trajectory across the northeastern Australian waters. Using observations from remote sensing data, Argo float and HYCOM reanalysis data, post-cyclone measurements revealed a significant increase in sea surface salinity and chlorophyll concentration, along with rapid cooling of sea surface temperature. These changes were accompanied by a deepening of the mixed layer and a reduction in sea surface height anomaly. These oceanic responses were particularly pronounced when the cyclone was at its peak intensity and moving slowly. Despite the presence of a deeper upper warm layer on the left side(lower latitude) of the cyclone's path, the unusual west-to-east trajectory of Harold still induced stronger oceanic responses on the left side of its track than on the right, the phenomenon occurred due to the enhanced resonance effect between winds and near-inertial currents on the left side of the cyclone′s path. Further analysis indicates that oceanic changes at depths shallower than 100 m were primarily driven by mixing due to shear instability in the current triggered by the cyclone, while responses at depths greater than 100 m were likely dominated by upwelling.