Study on Internal Waves over the Bay of Bengal Using ALOS PALSAR L band SAR Imageries

Abstract

Using ALOS PALSAR L-band SAR data, internal waves (IWs) with distinct characteristics ranging from weak manifestations to strong signatures are observed throughout the continental shelf edge of the Bay of Bengal and are not confined to a particular region or season. The wavelength, phase speed, and amplitude may vary depending upon the oceanic environmental conditions. The wavelengths computed from the present study vary from 0.17 to 4.8 km, and the phase speed ranges from 0.04 to 0.2 m/s. An attempt was made to study the morphological features of IWs using SAR imagery. IWs with different signatures (elevation and depression) were observed. Interestingly, they coexist simultaneously and crossover in the BOB. This may imply that either the IWs generated from the deep ocean propagating over shelf regions may be reflected or that river discharge may act as a force to disturb stratified layers. In this study, depressed IWs generated off the Kakinada region by the Godavari River plume were observed, and similar IW characteristics were observed in the head BOB. This may imply that many other major and minor rivers may act as another source for the generation of IWs. However, this aspect of the study needs further investigation in the BOB.