Acoustic propagation in shallow waters of south east Arabian Sea using Normal mode approach

The principal characteristic observed in this study is that for downward refracting profile, long range propagation takes place exclusively via bottom interacting paths, and for upward profile, a surface duct prevails. Directionality pattern for shallow sources, for a downward profile, exhibits a null along the horizontal as a consequence of modal propagation, and the null gets filled up for an upward profile. Normal mode approach is well suitable for defining shallow water propagation and is capable of handling variations in environment, physical oceanography and source characteristics. Site specific seasonal variation is clearly established which can be made use of in conducting SONAR exercises.