Objective mapping of observed sub-surface mesoscale cold core eddy in the Bay of Bengal by stochastic inverse technique with tomographically simulated travel times

Abstract

Present study consists the acoustic characteristics of a sub-surface cold core eddy observed (below the mixed layer between depths of 50 and 300m, with a diameter of about 200 km having temperature drop of 5ºC at the center) in the Bay of Bengal during south-west monsoon season and explore possibility to reconstruct the acoustic profile of the eddy by Stochastic Inverse Technique. A simulation experiment on forward and inverse problems for observed sound velocity perturbation field has been attempted for a range of 650 km (in the vertical slice) keeping the single source-receiver configuration (at the channel axis depth) in the SOFAR channel, under peculiar characteristics viz, depth-limited environment and weak gradient waters of the Bay of Bengal. For the formulation of the Stochastic Inverse, both vertical and horizontal structure of the ocean has been modeled using empirical orthogonal modes. Present Ocean Acoustic Tomography’s (OAT’s) simulation experiment results reveal that one can objectively map/monitor even the small mesoscale sub-surface eddies by stochastic inverse technique keeping single source and receiver in the SOFAR channel separated probably by larger distances also under such depth-limited environment of the Bay of Bengal.