Research On Response Characteristics Of Upper Ocean To Tropical Cyclone Based On Field Observation

In this paper,the most common tropical cyclone in the weather system with abominable sea state is studied.The sea current data observed by subsurface buoy,the temperature and salt data observed by Argo buoy,the biochemical data and the satellite remote sensing data are combined to study the upper ocean response characteristics of South China Sea and the Arabian Sea caused by tropical cyclones.At the same time,the characteristics of temperature and salt structure and the chlorophyll concentration of seawater during the passage of tropical cyclon were studied.Through case analysis,it is found that:The passage of tropical cyclones can induce strong vertical mixing and Ekman suction,leading to significant upwelling.This changes the distribution characteristics of the water in the ocean,resulting in the obvious decrease of sea surface temperature,the rise of thermocline,the decrease of sea surface height and the sharp increase of chlorophyll-a concentration on the sea surface near its moving path.At the same time,the analysis of the wavenumber spectrum and the vertical current component shows that the energy flux of the near-inertial oscillation mainly propagates downward.Affected by background vorticity,the frequency of near-inertial oscillations changes during the propagation process,i.e.blue shift or red shift.The results of the bi-coherence analysis show that there is a significant wave-wave interaction between near-inertial oscillation and half-day internal tide.The study found that the propagation and attenuation of near-inertial oscillations greatly promoted local ocean mixing.The stratified structure of seawater and various oceanographic processes play a role in regulating the propagation and distribution of near-inertial oscillations.With global warming,the intensity and frequency of tropical cyclones are expected to increase in the future.Considering the important role of tropical cyclones in local physics and ecosystems,we should pay more attention to the response of upper oceans to tropical cyclones in the future.