Long-Range Propagation of Sonic Boom from the Concorde Airliner: Analyses and Simulations

The reverse problem of finding the position of a supersonic aircraft from infrasound signals recorded at a long distance is dealt with in this paper through analyses of signals generated by the sonic boom of a Concorde aircraft as it was getting close to the French coasts. The signals generated by New York-Paris flights were recorded at very different distances (southwestern France and Normandy). Signals from the southwest were used to define and to test several models (meteorology, propagation, and atmospheric absorption). Signals from Normandy enabled us to apply these models to the reverse problem. Goniometric and spectral analyses associated with these models provide an estimation of the wave train direction and the distance to the sound source, which gives a bearing-and-distance localization of the aircraft. The validation consists of verifying that a reverse ray tracing from the measurement site reaches the aircraft trajectory and that a direct ray tracing launched from this point perpendicularly to the Mach cone can reach the measurement site despite these restricting conditions. In the present study, the calculation of ray paths and Concorde flight data takes account of the Earth's curvature and the weather surveys of the day.