Inter-seasonal variability of internal tides in the western Bay of Bengal

MITgcm is configured in a realistic situation to study the inter-seasonal variability of internal waves (IWs) in the western Bay of Bengal. Monthly climatology of the density fields from WOA09, modified ETOPO2 topography and barotropic tidal forcing are feed to the model for simulating IWs. The preliminary objective of the study is to identify IWs through the stratification and topographic configuration that support IWs. In this context numerical experiments are performed for January, April, July and October representing the winter, pre-monsoon, summer monsoon and post-monsoon, respectively, and analyses are made extensively over the western Bay of Bengal. Mixing caused by density overturning and shear instability is studied at the Gopalpur cross section for all seasons. The density time series are subjected to spectral analysis to find the energy associated with IWs of semi-diurnal frequency. Analysis depicts that the spectral estimates are high in the concave coastline pockets in the southern part and over a broader region on the shelf slope in the northern part. October shows higher estimates in response to highly stratified waters. Several cross sections are analyzed to obtain the spectral energy extent over the shelf slope. It is noticed in October that the peak estimate is within the shelf for shelf angles greater than 0.12 degrees and it falls outside the shelf for shelf angles less than 0.12 degrees.