Parameter coupling in broadband geoacoustic inversion

Abstract

For many geoacoustic inverse problems involving a single frequency data set, the search parameters are often strongly coupled to one another. This may mean that individual parameters are difficult to determine, but combinations of parameters can be resolved. In terms of the optimization process, the parameter landscape that is being searched has multidimensional valleys that hinder location of a global minimum. A coordinate rotation technique has been developed [J. Acoust. Soc. Am. 98, 1637–1644 (1995)] to speed the search for optimal parameters. This technique also gives valuable information about the parameter hierarchy and parameter couplings. One approach to decoupling the parameters and obtaining realistic physical parameter values is to process broadband data or multifrequency data. A new fast forward modeling technique [J. Acoust. Soc. Am. 106, 1727–1731 (1999)] makes it possible to consider broadband data for geoacoustic inversion. The coordinate rotation technique is combined with fast forward modeling to study parameter couplings for broadband and multifrequency problems. [Work supported by ONR.]