Abstract:

This paper will discuss progress that has been made in modeling range-dependent propagation problems and outline some of the unresolved problems. The parabolic equation (PE) method has proven to be the most useful approach for solving range-dependent problems. Finite-difference solutions and range-dependent mode and spectral solutions are useful for confirming the accuracy of PE solutions and for solving problems that PE techniques cannot handle (or cannot yet handle). Combinations of these approaches, such as the coupled mode PE, are also useful. In the mid 1980s, it was widely believed that there was not much left to do in propagation modeling. The amount of work that has been done in the past decade or so is evidence of how shortsighted this view was. Although there now exist accurate and efficient techniques for solving a wide variety of range-dependent problems, there still remain important problems to be solved. [Work supported by ONR.]