Progress toward an acoustic point to point ray tracing method in a stratified atmosphere with wind

Abstract

NASA is investigating acoustic propagation capabilities to accommodate a point to point propagation prediction scheme defining a ray between a specific source–observer pair in an inhomogeneous stratified atmosphere with wind. A 4D space-time ray method based on the null geodesic equations yields two main benefits over classical 3D Euclidian reduced ray equations: (1) it poses a valid two point boundary value problem for the rays connecting two locations; and (2) the solution method is valid throughout the whole domain including at ray turning points without the need for piecewise definitions. The resulting two point boundary value problem and the constant horizontal slowness vectors, which are a result of the stratified medium assumption, allow the desired (t, x, y, z) ray trace. The presentation highlights the equations and inputs required to solve the 4D ray trace. The solution to this two point boundary value problem will create the groundwork for efficient future NASA propagation codes.