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A description of a program for computation of acoustic fields in 3D shallow-water waveguides of arbitrary form is presented. This program is a C++ implementation of a numerical solver of wide-angle mode parabolic equations. The user can specify sound speed distribution, bottom relief, and the structure of bottom layers via configuration files when performing acoustic field simulation. The output of the program consists of one or several horizontal cut planes of the acoustic pressure field at specified depths. One of the main advantages of the implemented method is its high computational efficiency. The developed program is open-source and available online. It can be of interest for specialists in different areas of ocean acoustics who perform the modeling of sound propagation in course of the solution of various practical problems.

The modelling of sound propagation in the ocean by the solution of mode parabolic equations is discussed. Mode parabolic equations can be obtained as the one-way approximation to horizontal refraction equations for modal amplitudes. Their wide-angle capabilities depend on the order of the Pade approximation of the involved pseudo-differential operators. Various aspects of numerical solution methods for wide-angle mode parabolic equations are considered in detail, including artificial domain truncation and Cauchy initial data for the point source field approximation. The capabilities of the discussed numerical approaches are demonstrated in several important test cases, including the problems of sound propagation in a penetrable wedge and in a sea with an underwater canyon.

Recently a new approach to the modeling of one-way wave propagation in Kerr media was proposed [1]. Within this approach the solution of the nonlinear Helmholtz equation is approximated by a series of solutions of iterative parabolic equations (IPEs). It was also shown that IPEs take the nonparaxial propagation effects into account. In this study we develop an efficient pseudospectral numerical method for solving the system of IPEs. The method is a generalization of an exponential time differencing (ETD) method for the nonlinear Schrodinger equation [2]. The ETD technique is well-suited for the system of IPEs, as it allows to reduce the order of the derivative in the input term.