Assessment of the Hybrid Propagation Model, Volume 1: Analysis of Noise Propagation Effects

This is the first of two volumes of a report on the Hybrid Propagation Model (HPM), an advanced prediction model for aviation noise propagation. This volume presents the noise level predictions for eleven different sets of propagation conditions, run by the HPM. The conditions include effects of uneven terrain, refractive atmosphere, and ground type transitions. The results are analyzed in detail and comparisons are made across four different source altitudes and between the different component models of the HPM. In addition, a scheme of “intelligent switching” between the HPM’s component models is posed as an approach to address the long runtimes of the HPM. The feasibility of this strategy is discussed and some points of caution regarding its implementation are identified. HPM results are compared to the Integrated Noise Model (INM) under uneven terrain conditions in Volume 2 of this report. The goal of this research is to enhance the modeling capabilities of the Aviation Environmental Design Tool (AEDT) and INM, particularly in complicated environments such as National Parks.