On the possibility of monitoring El Niño by using modal ocean acoustic tomography

The possibility of monitoring El Niño by using the modal acoustic tomography (MOAT) is discussed. It is found that the inversion of El Niño profile with linear inversion scheme is less successful than the mid-ocean eddy case indicated by the condition number of the kernel matrix. However, based on a simple yet realistic acoustic model of El Niño, it appears that it might be possible to detect temperature fluctuations associated with El Niño’s by examining a proper set of modal features of the acoustic field. Numerical simulation illustrated that a fair reconstructed El Niño profile could be obtained by using the ‘‘damped least-squares’’ inversion incorporating the singular value decomposition (SVD) analysis.