I often deal with industrial noise of big plants. I usually use acoustic software for the simulations. Sometimes it is not possible to define correctly the meteorologic parameters. If there are not available meteorological data for the long period how do you usually organizanize your study?
By meteorological data I understanf, pressure, temperature and humidity or air composition! In the absence of long term data, one can use ensemble averages of available data for the period of interest and use the averages in the acoustic simulation. As an example, one can compute an average speed of sound based on some ensemble averaged temperature and air composition. This off course is an approximation to what you are trying to do but at least you have place o start from and improve from there.
Dear Francesca,
in one of my book chapter I have cited a robust model of sound attenuation over a wide range of frequencies. You can find it in "Bats sonar calls and its application in sonar systems" (chapter 3) and papers of Brass and Evans.
In that case, I usually take into account the data provided by the nearest meteorological observatory
Have you ever tried to compare the results using different tecnichal standards (Concawe method, ISO 9613, NMPB)?
Hi Francesca, you can use this website to estimate the absorption constant as a function of pressure, humidity, temperature and frequency... Hope it helps.
http://resource.npl.co.uk/acoustics/techguides/absorption/
Hi Francesca, could you please explain more what you would like to do? When you say 'data for the long period', I presume you mean historical data (in the past). It really depends on several factors, i.e. what is your spatial resolution you want to work at. For example, do you need data with a resolution of 1-10 km or is it ok if you have up to 100 km? The coarser the resolution, the more data you will find. For example, you can try the ERA-40 Reanalysis Data from ECMWF. To the best of my knowledge, those are free for research purposes.
Thank you Vasilis. Yes I mean historical data. For the strategic noise mapping you have to condider the meteorological data of the last ten years.
You could start from here then: http://apps.ecmwf.int/datasets/data/era40-daily/
Do you know what kind of meteorological parameters you need? It should be more or less everything that has to do with boundary layer properties and of course atmospheric pressure.
Yes Vasilis, the main problem are the acoustic commercial softwares. Sometimes is not very clear how the technical standards are implemented in it. May be you spend a lot of time to analyze the meteorological data and the software doen't really take in account about them.
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