Identification of internal waves off Visakhapatnam from Thermister chain

Abstract

An analysis of Internal Wave (IW) signatures by in-situ observations off Visakhapatnam has been presented to study the impact of IWs on acoustic field. Temperature data were collected for 44 hours at an interval of 2 minutes off Visakhapatnam (17 degrees 26.46'N and 83 degrees 31.20'E, and sonic depth 100 m) during 18-20 October 2006 using indigenously developed thermister chain to study the Internal Wave (IW) characteristics. Sound velocity realizations (in space and time) in the observed high frequency (HF) IW field is generated utilizing Garret-Munk (GM) model. Acoustic modeling is carried out in the generated IW HF field to compute transmission loss anomaly for source-receiver configuration at the depth of 20 m and range of 9 km. The anomaly explains the impact of IW on acoustic propagation characteristics in HF IW field and it was found to be 9.98 dB.