ABSTRACT
In this paper, we discuss application of nonlinear signal processing techniques to underwater electromagnetic data. Electromagnetic measurements provide a potentially useful complement to acoustic detection methods in littoral zones where high noise levels and reverberation in the littoral limit acoustic detection ranges. In shallow waters, for example, the ambient noise levels from wind-generated breaking waves are typically 10 to 100 times greater than those in deep water. Electromagnetic measurements are affected by noise as well. One source of electromagnetic fields in seawater is electrical currents induced by hydrodynamic flow in the Earth’s magnetic field. The ocean is a constantly moving conducting fluid [26], and ocean flows caused by gravity waves (wind waves and far-field swell), internal waves, turbulence, tides, and currents all result in electromagnetic field fluctuations.
