Sound propagation properties in the subtropical mode water in the Northwest Pacific Ocean
The subtropical mode water(STMW)in Northwest Pacific Ocean is a water mass with vertical homogeneity of temperature,salinity and density in the thermocline,which occurs in the summer in the Northwest Pacific Ocean.Due to the presence of STMW,the deep-sea sound speed profile shows a double thermocline structure,which has a strong impact on the deep-sea long-range sound propagation.In this paper,we compare and analyze the sound propagation patterns of typical sound speed profiles in STMW region in summer and winter.According to the results of this analysis,the sound propagation is a combination of similar SOFAR channel propagation and convergence zone propagation in the shallow sound channel under the summer sound speed profile environment.The rays with smaller grazing angles are confined in the shallow channel,increasing the arrival structure in the convergence zone and enhancing the sound energy in the shadow zone,the transmission loss in the second shadow zone is at most nearly 60 dB less than that in the winter sound speed profile environment.This paper provides an approximate expression for the cutoff frequency of the shallow channel,and the results of the analysis show that the cutoff frequency is primarily determined by the width of the shallow channel and the difference of sound speed in the positive gradient section.The cut-off frequency of the shallow channel in the STMW region in summer is primarily around 100 Hz.
Subtropical modal waterConvergence zoneArrival structureCut-off frequency
万方数据
维普
