HYPER: A hybrid parabolic equation-ray model for high-frequency underwater sound propagation

Abstract

The parabolic equation (PE) propagation model contains all diffraction effects, PE applies to fully range-dependent environments, and PE has no upper limit of validity in frequency. However, simple operation count estimates show that PE execution times increase proportional to at least the square of frequency, and thus PE becomes impractical to run on minicomputers at high frequencies (above about 500 Hz). The equations of geometrical acoustics can be solved in fully range dependent environments with execution times independent of frequency, but amplitudes and phases are not reliable because these equations do not contain diffraction effects. The HYPER (Hybrid PE-Ray) model uses only the ray trace portion of geometrical acoustics to locate the important propagation paths. Then HYPER solves a modified parabolic equation in a small region (decreasing with increasing frequency) near the ray paths and computes amplitudes and phases. Theoretical calcuations show that HYPER provides uniformly valid diffractive solutions in fully range dependent environments with execution times nearly independent of frequency. Thus HYPER should be practical to run on minicomputers at very high frequencies.