2 edition of Effect of weather and topography on the propagation of noise found in the catalog.
Effect of weather and topography on the propagation of noise
J. E. Piercy
by National Research Council of Canada, Division of physics in Ottawa
Written in English
|Statement||by J.E. Piercy, T.F.W. Embleton.|
|Contributions||Embleton, T. F. W., National Research Council of Canada. Division of Physics.|
|The Physical Object|
|Pagination||48,  p. :|
|Number of Pages||48|
The effects of topography on the climate of any given region are powerful. Mountain ranges create barriers that alter wind and precipitation patterns. Topographical features such as narrow canyons channel and amplify winds. Mountains and plateaus are exposed to the cooler temperatures of higher altitudes. The. The final filtered data for field waveforms are shown in black lines in Figures 2c, 2d, 3c, and 3d; the detailed method for the filter used to minimize the effect of the 60‐kHz noise is presented in Appendix Appendix A. 3 FDTD Modeling. In this section, a full‐wave FDTD model including the effect of the ionospheric reflections and the propagation effects of a mountainous terrain is presented.
Effects of Weather on Noise The Noise Office receives many noise complaints from residents who notice that airplane noise is much worse on one day versus another. Generally, the amount of noise emitted from a particular jet aircraft during landing, departure, or . Sound travels in the form of waves of vibrating particles colliding with each other in the direction of transmission. That is why sound can travel through water, air and even solids, but it cannot propagate through a vacuum. Sound depends on the medium through which it .
Our engineers use manufacturer data, information provided by the relevant authorities and/or field data to construct noise propagation models. The model takes into account and includes weather conditions, topography, reflectivity and frequency information in the calculations to determine compliance with regulatory requirements. that incorporates data on land cover, topography, and weather conditions to model spatial patterns of noise propagation around one or multiple sound sources (Reed et al. ). We used previously compiled data on oil and natural gas well locations within 10 km of the Mesa Verde National Park boundary (Leu et al. ).
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Most people know that weather can influence sound propagation, but by how much. First of all, wind alters sound propagation by the mechanism of refraction; that is, wind bends sound waves. Wind nearer to the ground moves more slowly than wind at higher altitudes, due to surface characteristics such as hills, trees, and man-made structures that interfere with the wind.
By itself, wind has very limited effects on noise propagation, other than to increase or decrease the speed of sound. At short distances, up to 50m, the wind has minor influence on the measured sound level. For longer distances, the wind effects become appreciably greater. Over open ground, substantial vertical wind velocity gradients commonly exist.
Backed by field measurements, this article provides a practical look at the effect of weather conditions on noise levels in order to raise awareness of the importance of meteorology in noise measurements. Noise propagation theory. Noise is essentially a sound wave that, if isotropic, will radiate outwards equally in all directions from the source.
meteorological effects on noise propagation. Japan Aerospace Exploration Agency (JAXA) has developed a noise prediction model taking into account the effect of wind direction and magnitude, humidity and air temperature on noise propagation. The impact of wind uncertainties on noise.
However, noise propagation is susceptible to environmental factors and weather conditions, including rain, wind speed, and wind direction  .
According to Ma and Nystuen , even. A general review is presented of most areas of sound‐propagation outdoors that are of interest for the control of community noise. These areas are geometrical spreading, atmospheric absorption, ground effect, (near horizontal propagation in a homogenous atmosphere close to flat ground), refraction, the effect of atmospheric turbulence, and the effect of topography (elevation, hillsides.
At ranges of one to three miles especially, the noise levels due to operations on the ground (e.g., acceleration, thrust reversal, engine run‐ups) are strongly dependent on topography and weather. Listeners up a hillside lose some or all of the noise reduction that would otherwise be provided over flat land by ground shielding.
The effects of weather are variable, but under conditions of. to some extent the effect of increased propagated noise on wave propagation see Davies . the systems overall signal-to-noise ratio.
Peak densities of the ionospheric layers vary between l04 and > el/cm3. Inserting these numbers into Equation Principles of Ionospheric Sounding. situations noise may adversely affect health in the form of acoustical energy.
Sources of Noise topography, meteorological conditions and low background levels are unfavourable (for example, mountain areas). The long-distance propagation of noise - and. In various parts of Europe, topography has a marked effect on the climate, not only of the uplands themselves but also of adjacent areas.
Apart from the more obvious effects on temperatures, precipitation amounts and winds, the major mountain masses also affect. Spectral-element numerical simulations indicate that high-resolution topography can change peak ground velocity (PGV) values in mountainous areas by ±50% compared to a half-space response.
We further demonstrate that large-scale topography can affect the propagation. Effects of atmospheric structure and topography are included in a vertical section parallel to the wave propagation direction.
The simulation successfully reproduced the variations of amplitudes. planning and design purposes. However, particularly for systems with digital modulation, small scale effects due to buildings, topography, etc., may affect performance and service quality.
Finally some information is given on measurements and on the relative phase of the ground wave. 2 The development of surface wave theory. Meteorological Conditions - Aweather Effects of Wind Over open ground, substantial vertical wind velocity gradients commonly exist due to friction between the moving air and the ground.
Wind speed profiles are strongly dependent on the time of day, weather conditions and the nature of the surface.
The wind speed, in the absence of. for effects to noise propagation from spherical spreading, atmospheric absorption, vegetation and ground cover, weather (wind, temperature, relative humidity and cloud cover), topography, and the ambient soundscape. The effect of topography on the time-mean flow and storm-track intensity is illustrated with a nearly identical integration, performed with a 2-km high mountain, shown in the right column of Fig.
In the presence of topography (thick contour lines), the subtropical and polar-front jets are combined with each other and, more importantly. Digital topographic databases for propagation studies P Method for predicting sky-wave field strengths in the frequency range to kHz Note - Suppressed on 20/10/95 (RA) P Propagation factors affecting frequency sharing in HF terrestrial systems P Noise propagation evaluation is a complex process.
Fundamental information used in sound studies, such as terminology and equations, are presented here. The noise at a receiver is described by two components; the discrete normal modes of the particular shallow water channel, and the continuous spectrum.
The extent of the mode contribution is controlled by the environmental conditions (bottom type, sound speed profile), and in hard bottom conditions these can dominate the noise.
Presentation given by Joseph Czech during NOISE-CON in San Diego, CA on Weather Effects on Propagation of Aircraft Noise. To download the full presentation, submit your information on the right.
About the Author. Joseph J. Czech, PE Principal Consultant. Topography, which we approximated using the standardized percentage of wind turbines visible, affected wind turbine noise such that when fewer turbines were visible (indicating more hilly topography), wind turbine noise levels were lower.
This result is consistent with the effects of topography on sound propagation.Project 02 - Sound/Emission Propagation. As part of the PARTNER noise research program, the Source Emission and Propagation project has the goals to provide a better understanding of aviation noise problems and to contribute to the development of improved noise impact prediction tools that lead to developing solutions.The speed of sound is affected by temperature and humidity.
Because it is less dense, sound passes through hot air faster than it passes through cold air. For this reason, temperature gradients cause refraction effects, which are for the most part, nothing to worry about.