Demarcating turbulence regions in the atmospheric boundary layer for the simulation of en route supersonic noise

With civil supersonic aircraft on the horizon, it is necessary to simulate en route noise propagation for international noise certification schemes. Turbulence is an important random atmospheric phenomenon that affects the propagation of aircraft-generated en route noise through the atmospheric boundary layer. While the original release of the propagation tool KZKFourier accounts for turbulence in the atmospheric boundary layer, it did not consider the physics of the different height-dependent regions within it. For example, shear-induced vector turbulence dominates the surface layer’s bottom tenth of the atmospheric boundary layer, whereas buoyancy-induced vector turbulence dominates the mixed layer above the surface layer. Through the revision of length, friction, and velocity scales of the spectra equations that prescribe vector turbulence, progress has been made in incorporating different turbulence behavior specific to corresponding height-dependent regions of the atmospheric boundary layer generated by KZKFourier. With these more realistic representations of the atmosphere, improved realizations of ground waveforms and their sound metrics can be calculated. [Work supported by the FAA through ASCENT Project 57 under the supervision of Sandy Liu. Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the FAA.]