Research On Processing And Application Of Argo Trajectory Data In South China Sea

South China Sea(SCS)has a complex environment and the measured data in mid-depth is rare.The understanding of circulation structure of the SCS doesn't go far enough.In 1998,the international Argo plan began to implement.More and more ocean temperature,salinity profile data within 2000 m can be obtained.Besides,since in the drift period,the Argo float has no dynamic effect,the drift trajectory also provides us with a new method to invert ocean currents.The main contents of this paper are as follows:(1)Research on Argo trajectory data processing method in the SCS.Based on the 114 Argo floats from 2006 to 2016 in the SCS,a data preprocessing and fuzzy processing method has been proposed.Least squares method based on the inertial current and background current has been used to invert the current velocity on the surface and parking depth of Argo float in this paper.(2)Analysis of typical physical phenomena in the SCS observed by the single Argo float.Influenced by the west strengthen,mesoscale eddy and current changes in Luzon Strait,part of Argo floats' trajectories were changed.Results show that: In winter,there is a strong current from northeast to southwest in the west of SCS,current velocities are very big.The anticyclonic eddy exists obviously along the coast of Vietnam,and Luzon cold eddy exists in the northwest of Luzon Island in winter and dies out in spring.In summer,on the surface of SCS,the current is from SCS to the Pacific through Luzon Strait,but the current from the Pacific to SCS is in the winter.(3)Analysis of gridding seasonal average current field based on the velocities inverted by Argo trajectory.In order to analyze circulation structure of basin scale in the SCS,surface and mid-depth(1200m)gridding seasonal average current field has been formed by using Divand variational analysis method and compared with HYCOM reanalysis seasonal average current field in this paper.The results show that both of them have good consistency.Surface current field changes with season obviously.In winter,it is cyclonic circulation structure and in summer it is anticyclonic circulation structure.The mid-depth current field is anticyclonic circulation structure all over the year.(4)Analysis of current velocities error inverted by Argo trajectory data.YoMaHa'07 data and HYCOM reanalysis data were introduced and velocities in the surface and parking depth with both of the two data were compared.At last error distribution has been analyzed.This paper shows that using Argo trajectory data to invert surface and mid-depth current velocities is an effective method to using measured ocean observations.Research aimed at the single Argo float in the SCS between 2006 and 2016 reveals the typical physical ocean phenomena.Gridding surface and mid-depth(1200m)current fields show the seasonal changes of circulation structure of basin scale in the SCS.