Oceanic internal waves and their influence in the acoustic propagation in the northern indian ocean

Abstract

Internal waves are ubiquitous phenomena in the ocean and defined by newlinethe stratification of water column, bottom topography and type of sources newline(tide, wind, submarine earthquakes, landslides etc). Buoyancy frequency is an newlineindicator of these fluctuations and energy of fluctuations is varying with newlineseason due to the difference in stratification. Oceanic internal waves can newlineproduce temporal and spatial variability in sound speed by inducing newlinefluctuation in temperature and salinity in ocean environment. Sound speed is newlinethe major parameter that defines sound propagation in the ocean and its newlinevariability due to internal waves can influence transmission characteristics newlinethrough the ocean environment. Since sound is the only effective mode of newlinecommunication in the ocean and oceanic internal waves have impact on sound newlinespeed, understanding the influence of internal waves on underwater sound newlinepropagation is very important in ocean acoustic applications. The internal wave newlineeffect on sound propagation has been studied in this research in terms of newlinetransmission loss. This study also focuses on characteristics of deep and newlineshallow water internal waves and influence of internal wave on sound newlinepropagation in the Northern Indian Ocean (NIO). Satellite imageries and time newlineseries records of CTD revealed the presence and features of internal waves in newlinethe study location. Semidiurnal tide (M2) induced internal waves are observed newlinein the deep waters of Andaman Sea. Winter (January), Pre (March) and Post newline(October) monsoon seasons experience strong internal wave activity due to newlinestratification whereas July shows weak energy due to mixing (weak newlinestratification). Shallow waters of North West Bay of Bengal (NWBoB) show newlinethe presence of semi diurnal and compound tidal frequencies of internal waves newlineduring winter (February). newline