Acoustical Characteristics and Simulated Tomographic Inversion of a Cold Core Eddy in the Bay of Bengal
Acoustic characteristics of a subsurface, cold core eddy observed in the Bay of Bengal during the southwest monsoon period is presented based on conductivity temperature depth data from 42 stations. The effect of the eddy is to reduce the ambient sound speed by about 10 m/s. Under the
influence of the eddy, the depth of the SOFAR channel axis remains constant (1600 m), which otherwise should have shown a deepening in this region. Simulated ray arrival structure depicts the typical characteristics of a weak acoustic wave guide in the Bay of Bengal – the early arrival
cluster of near-axial flat angle rays, later arrivals of deep turning rays, followed by the weak latest arrivals of near-surface turning rays. The arrivals of the acoustic rays are delayed by about 100–200 ms under the influence of the eddy. The intensity computations show that when
a ray passes through the eddy, it suffers an additional loss of 20–25 dB. From the simulated travel time delays, the eddy profile is reconstructed through a generalised inversion, based on the singular value decomposition technique, the numerical experiment shows that 18 eigenrays with
9 layers enable reconstuction of the eddy profile edequately using 9 eigenmodes.
Document Type: Research Article
Publication date: 01 September 1997
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