Reconstruction of Bottom and Water Parameters in Shelf Zone on the Basis of Fusion of Geophysical and Acoustical Data

Abstract

Setup of experiment concerning determination of bottom and water properties in shallow water can be presented in the following way. Radiated acoustical signal from the fixed (the so called stationary track) or from the moving source, is being received by the fixed vertical array of hydrophones placed on rather long distance from the source (from tens up to hundreds km). Besides acoustical field, produced by our sources we can register noise field excited by wind waves. Set of characteristics of the sound field, obtained as a result of experiment will be denoted by vector A exp with dimension determined for example by the total number of hydrophones measuring the sound filed of the vertical interference structure, or by the number of frequency points in the spectrum of the broadband signal. This dimension can be of the order from several tens up to several hundreds in dependence on situation. During this experiment we independently conduct measurements of different parameters of environment. We mean measurements by CTD (Conductivity, Temperature, Depth) — probe, which allows us to know sound speed profile, ADCP (Acoustical Doppler Current Profiler) for registration of water motion, different sorts of echo-sounders, wind speed meter for registration of surface waves, analysis of samples of sediment obtained by the drilling, etc. Some of these parameters can be measured rather accurately (for example depth of water or sound speed profile), another ones have more high degree of uncertainty (sound speed and absorption coefficient in sediment) so we could suppose these parameters as unknown. We denote set of unknown parameters by the vector p with comparatively small dimension (about ten) On the basis of mentioned independent measurements of environment characteristics we construct model of the waveguide within the framework of which we can calculate the same sound field on the vertical array.