Low Frequency Geoacoustic Inversion Method

Abstract : The primary long term objective of this project is to determine a fast and accurate inversion method to estimate bottom properties in shallow water. The objectives of this year s work (FY12) included: 1) continued study of a new deterministic low frequency (LF) geoacoustic inversion (G.I.) method recently featuring the minimization processor (Tolstoy, 10 and 12); 2) demonstration that horizontal arrays can be successfully used for G.I. with the new method (presented at the fall ASA); 3) preparation the LF G.I. method to be applied to ranges beyond 2 km (KRAKEN was integrated into the processing software in preparation for the D. Knobles data); 4) initiation of efforts for the consideration of frequencies above 100Hz at close range (leading to consideration of such frequencies at longer ranges; this was sugggested by K. Becker this past spring). We have already seen that at ranges beyond 1km and at freqs above 100Hz inversion can be problematic if all geoacoustic, environmental, and geometric parameters are unknown.