Outdoor sound propagation reference model developed in the european harmonoise project

Abstract

The paper describes the determination of vertical profiles of the effective sound speed from meteorological measurements at only one height above ground. The vertical profiles are needed for the prediction of long-term sound levels under the consideration of atmospheric refraction. The study is based on the results of field campaigns which were performed during the European project HARMONOISE. In a first step different theoretical-empirical approaches were tested to derive vertical effective sound speed profiles from measured turbulent fluxes of momentum and heat. The results of the profile generation were compared with sound speed profiles derived from profile measurements at a meteorological tower. It was found that a two-parameter logarithmic-linear approach is sufficiently accurate to generate vertical sound speed profiles. In a second step profiles generated on the basis of local flux measurements were compared with those based on conventional data of a nearby routine weather station. If local measurements are not available the representativeness of nearby weather stations has to be carefully checked, above all in topographically structured terrain.