Applications and time-domain solution of higher-order parabolic equations in underwater acoustics

A higher-order parabolic equation and the corresponding higher-order time-domain parabolic equation are derived from a Padé series and solved numerically. These models provide accurate solutions for problems involving very-wide-angle propagation (e.g., propagation in the nearfield or over a hard ocean bottom); propagation in domains in which sound-speed variations are large (e.g., propagation in deep water, deep within the ocean bottom, in high-speed ocean bottoms, and possibly of different wave types); and propagation out to very long ranges. The possibility of modeling elastic wave propagation with a similar approach is considered.