Research On The Characteristics Of Spatio-temporal Variation Of Sound Velocity Profile Structure In The Indian Ocean

The sound velocity profile determines the sound propagation path and sound propagation loss,and it is of great significance to discuss the change rule of the sound velocity profile morphology and the spatio-temporal change of the vocal tract for the prediction of the sound field,the inversion of acoustic parameters,and underwater acoustic communication.There are few studies on the sound velocity profile in the Indian Ocean(especially in the South Indian Ocean).It lies in the limitation of the vertical gradient method in the analysis of sound velocity structure and the applicability in the Indian Ocean.In this paper,the optimal segmentation method in multivariate statistical analysis is used to analyze the sonic troposphere,and the characteristics of the sonic velocity profile in the Indian Ocean are calculated using the real-time observation matrix data of the geostrophic oceanography in 2000 and 2018 to obtain the sonic troposphere.The vertical structure characteristics and the law of spatio-temporal changes.The results of the study show that:There are obvious seasonal and regional changes in the surface channel distribution of the Indian Ocean.Surface channel shows a semi-annual cycle change at north 10°S in the Indian Ocean,and it shows an annual cycle change at south 10°S in the Indian Ocean.Surface channel is deepest at 40°S in the Indian ocean in September.The deep channel generally exists at south 10°N.At north 45°S,the deep channel in the eastern area is shallower than that in the western area.And the deep channel at south 45°S is the shallowest,which is with little seasonal variation.In the vicinity of the 60°E cross section and the 90°E cross section at 45°S,there is an invariable sound velocity layer ranging from the surface layer to 1000 m below the surface.The velocity of sound south of 45°S is roughly positive gradient.The sound velocity profile of the Indian Ocean can be divided into three types:single spring layer,double spring layer and triple spring layer,and four season models:spring model,summer model,autumn model and winter model.The analysis results of sound velocity profile and channel distribution have certain reference significance for underwater acoustic propagation and underwater communication.