Environmental mismatching effects on source localization processing in mode space

The performance degradation of the matched field processing (MFP) caused by environmental mismatching has been an intriguing subject. A great deal of study has been done by numerical simulations. In this paper, this problem is studied analytically. Analytic investigation is important because it reveals some of the physical insights and provides guidelines for a “self‐coherent” scheme [H. Bucker, J. Acoust. Soc. Am. Suppl. 1 84, S19 (1988)]. It has been illustrated that the source range information is associated with the modal phase difference and the source depth information is associated with the modal amplitude ratio when MFP is performed in mode space. Therefore, the modal wavenumber plays a key role in source localization. Mismatching effects can be investigated analytically by taking advantage of calculating the modal wavenumber error by modal perturbation theory. [Work supported by NOAA and NOSC.]