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Carefully validated long-range sound propagation measurements with extensive meteorological instrumentation were continued for 612 days without interruption, around the clock, resulting in a database with millions of files, terabytes of sound and environmental data, and hundreds of pages of documentation. More than 100 environmental variables were analysed by statistical means, and many statistically highly significant dependencies linked to excess attenuation were found. At a distance of 3 km from the source, excess attenuation was spread over a dynamic range of 80 dB, with differences of 10 dB between individual quarters of the year; also, negative excess attenuation at frequencies below 400 Hz existed. The low frequencies were affected mainly by the stability characteristics of the atmosphere and the lapse rate. Humidity; lapse rate; sensible heat flux; and longitudinal, transverse, and vertical turbulence intensities explain excess attenuation at higher frequencies to a statistically highly significant extent. Through application of a wide range of regression analyses, a set of criteria for frequency-dependent uncertainty in sound propagation was created. These criteria were incorporated into a software module, which, together with a state-of-the-art physical sound propagation calculation module, makes it possible to perform environmental noise assessments with known uncertainty. This approach can be applied to the shortterm measurements too and it was shown that some of the most complex meteorological variables, among them atmospheric turbulence, can be taken into account. Comparison with two standardised noise modelling methods showed that the statistical model covers well a range of uncertainty notmatched with the standardisedmethods and themeasured excess attenuation fit within the limits of predicted uncertainty.

Carefully validated long-range sound propagation measurements with extensive meteorological instrumentation were continued for 612 days without interruption, around the clock, resulting in a database with millions of files, terabytes of sound and environmental data, and hundreds of pages of documentation. More than 100 environmental variables were analysed by statistical means, and many statistically highly significant dependencies linked to excess attenuation were found. At a distance of 3 km from the source, excess attenuation was spread over a dynamic range of 80 dB, with differences of 10 dB between individual quarters of the year; also, negative excess attenuation at frequencies below 400 Hz existed. The low frequencies were affected mainly by the stability characteristics of the atmosphere and the lapse rate. Humidity; lapse rate; sensible heat flux; and longitudinal, transverse, and vertical turbulence intensities explain excess attenuation at higher frequencies to a statistically highly significant extent. Through application of a wide range of regression analyses, a set of criteria for frequency-dependent uncertainty in sound propagation was created. These criteria were incorporated into a software module, which, together with a state-of-the-art physical sound propagation calculation module, makes it possible to perform environmental noise assessments with known uncertainty. This approach can be applied to the shortterm measurements too and it was shown that some of the most complex meteorological variables, among them atmospheric turbulence, can be taken into account. Comparison with two standardised noise modelling methods showed that the statistical model covers well a range of uncertainty notmatched with the standardisedmethods and themeasured excess attenuation fit within the limits of predicted uncertainty.

The Harmonoise reference model has been developed in order to predict long-term average sound levels in road and railway situations that are geometrically relatively simple but physically complex. The present paper describes all steps of calculations with this powerful model which includes several advanced numerical propagation methods to calculate the coupled effects of atmosphere, ground surface and obstacles on sound waves. The reference model employs a statistical description of the atmosphere, based on local meteorological data, as well as various impedance models for ground surfaces and other absorbing surfaces. Validations against in situ long-term measurements have been achieved in several sites; agreement between reference model and experimental results ranges from excellent in flat terrain situations down to fairly good in more complex configurations (hilly, viaduct). © S. Hirzel Verlag.

The Harmonoise reference model has been developed in order to predict long-term average sound levels in road and railway situations that are geometrically relatively simple but physically complex. The present paper describes all steps of calculations with this powerful model which includes several advanced numerical propagation methods to calculate the coupled effects of atmosphere, ground surface and obstacles on sound waves. The reference model employs a statistical description of the atmosphere, based on local meteorological data, as well as various impedance models for ground surfaces and other absorbing surfaces. Validations against in situ long-term measurements have been achieved in several sites; agreement between reference model and experimental results ranges from excellent in flat terrain situations down to fairly good in more complex configurations (hilly, viaduct). © S. Hirzel Verlag.

The results of six weeks of SODAR measurements are presented and compared with meteorological data and results obtained by various international measurements. The mean daily variations of the occurrence and the height of the typical echo structures LG, LE and S derived from analogous recordings correspond well with the occurrence of atmospheric surface inversions, elevated inversions and convective conditions. The echo structures are highly complex during front passages and convective precipitations.

Describes the main parts and the mode of operation of the vertical sodar ECHO-1 of the Heinrich-Hertz-Institute of Atmospheric Research and Geomagnetism of the Academy of Sciences of the GDR. With the aim of an efficient and objective interpretation of the echo data, especially for the operational use of the devices in meteorology, the possibility of a combination with commercial computer facilities is demonstrated. Some examples of computer-generated sodargrams are presented.

Summarization: A simplified, but quantitatively reliable approximation of atmospheric sound propagation is given by the standard parabolic equation. The waveguide is a cylindrically symmetric, unbounded, domain with an irregular lower boundary. The associated initial-boundary value problem uses a mixed-type boundary condition along the lower boundary and a nonlocal, absorbing boundary condition of the DtN (or NtD) type, applied on an artificial upper boundary. Exterior wave fields of a constant index of refraction and a linear, when squared (as function of height) one, are considered. The physical, complex waveguide reduces to an orthogonal computational domain by the means of a numerical transformation to generalized coordinates, fitting the lower, irregular boundary. The technique presented is of practical interest for its proper handling of complex ground topographies; it is interfaced with a mesh generator and processes the topographic data retrieved from a geographic information system, hence the transformation of coordinates is computed numerically. The transformed initial-boundary value problem (on the orthogonal computational domain) is discretized by the Crank–Nicolson in time and a continuous, piecewise linear finite element method in space. The propagation of cylindrically symmetric sound waves over a complex terrain, emitted to the atmosphere by a harmonic source, has been studied. The effectiveness of the numerical method introduced, is exploited on several test cases. Presented on: Applied Numerical Mathematics