5. TOMOGEAPHIC INVERSION OF INTERNAL SOLITARY WAVES (ISW)
The nonlinear internal waves in the ocean have been known for over a century, and extensive investigations were made in the early 1970s [12, 13]. Much more attention has been paid by the ocean acoustic community since 1990s, stimulated by Zhou's paper [14] which took the ISW as s possible candedate to explain the strong frequency -selected transmission loss observed in the shallow -water of the Yellow Sea. Here,the inversion scheme based on MTP is derived and the numerical simulation is performed based on the ISW data observed by the Coastal Probing Experiment (COPE) that was conducted by NOAA/ETL in September 1995 at the East pacific Shelf [15]. Figure 6 shows 12h of isotherm data recorded by FLIP;these data were transformed to space distribution for acoustic propagation simulations. It has been found that for lower frequency ( ＜ 100 Hz), adiabaticity can be held (see Fig.7).
If we take the constant depth of the thermocline, h0 = 5 m , as the backgroud, then the perturbed modal phase by the ISW is given by
