Modelling of coastal ocean environment for underwater surveillance

Abstract

Significance of ocean environment for underwater surveillance, namely for sonar systems, has been discussed in this paper. The passive as well as active sonar equations and the various parameters which are important for assessing sonar performance from environment point of view are highlighted. Some important published results which are available in the literature on the modelling of thermohaline structure of our coastal waters have been reviewed in this paper. Among 1-D mixed layer ocean models the model by Niiler and Kraus¹ shows lesser deviations on Mixed Layer Depth (MLD) and Mixed Layer Temperature (MLT) when compared to the observations. The model given by Price <i style="">et al </i>² simulates the Sea Surface Temperature (SST) and the vertical profile of temperature. The comparison of simulated values with observations revealed that the diurnal variability of SST is well represented through this model but deviations are noticed in the thermocline zone. The 1-D ocean models are simple and easy to implement for operational purposes because they are computationally less intensive. However, it was found that these models accumulate more error for long-term simulation due to non-inclusion of advection processes which are important in coastal as well as open ocean conditions. The observed and predicted results of a 3-D model proposed by Blumberg and Mellor³, also known as Princeton Ocean Model (POM), showed a reasonable good comparison and this model could simulate successfully the Arabian Sea mini warm pool which is an important phenomenon that occurs in the south-eastern Arabian Sea before the onset of summer monsoon.