Shallow water inversion with optimization and direct methods

Shallow water inversion with optimization and direct methods. Accurate knowledge of the ocean environment is a crucial factor in establish- ing national security, being intimately tied to accurate threat detection, local- ization, and identi cation. The goal of this work is to improve our knowledge of the ocean medium by solving inverse problems that use physics of sound propagation and statistical signal processing. Speci cally, using sequential l- tering, we plan to estimate the arrival times of multi-paths; these are related to source location and properties of the propagation medium. The ltering process will provide probability density functions of arrival times. Using a mathematical model for the inversion, these, in turn, will facilitate the cal- culation of probability density functions for source location, sound speed in the water column, bottom depth, sediment thickness, and sediment sound speed. Using this information, we will, subsequently, estimate attenuation pro les in the sediment. In a similar manner, for long range propagation we will track modal frequencies and arrival times, along with their correspond- ing amplitudes. The former will allow the estimation of sediment sound speed. The latter will allow the computation of probability density functions of amplitude ratios, which will be used to estimate sediment attenuation. An additional project entails work in direct inversion methods for sediment sound speed estimation. The goal is to develop a robust method with re- spect to noise, which has also small sensitivity with respect to assumptions. Finally, work will be performed in passive fathometer processing, identify- ing and modeling distortions in the fathometer output in order to improve re ector detection and localization.