Michel Vuillermoz, Filippo Berlier, Christian Tartin, Christian Tibone, Daniele Crea, Marco Cappio Borlino
Merano - AIA DAGA 2013
Influence of vertical temperature gradients on outdoor sound propagation in a narrow
valley
Politecnico di Torino
Objectives
Correlation between vertical temperature gradients and environmental noise, quantification of this correlation
Analysis on empirical data collected by ARPA vda (2006 / 2012)
Definition of a method to carachterize temperature profiles
Monitoring noise level related to different meteorological
conditions
Case study
Thermal inversion
Aosta city
12 January2012
Time [h]
Altitude [m]
500 700 900 1100 1300
0 2 4 6 8
Altitude [m]
Temperature [°C]
Standard temperature profile
Phenomenon
Thermometers location
Thermometers profile line
Steel factory
Sound-level meters location
Steel factory
Profiles decription method
Correlation: Thermal profiles - coefficients
Coefficient a
Coefficient b
Correlation Thermal profiles- coefficients
Coefficient distribution
Thermal inversion on the whole profile= 2,18 %
Thermal inversion partially on the profile = 18,27 %
Coefficient b (Gradient)
Thermal inversion situations
Thermal inversion rate
Altitude [m]
Frequency [%]
Create a clear correlation between temperature profiles and noise levels (similar profiles ↔ average noise)
Time and meteorological conditions imposed
Reasons for the classification
Noise level [dBA]
Coefficient b
42 44 46 48 50 52
Standard profile Gradient > 1,5 Thermal Huge gradient
Noise level [dBA]
South hillside L95 [dBA] –
200 [m] above the source44 46 48 50 52
Noise level [dBA]
South hillside L95 [dBA] –
200 [m] above the sourceAltitude
42 44 46 48 50 52
Standard profile Gradient > 1,5 Thermal Huge gradient
Noise level [dBA]
South hillside L95 [dBA] –
200 [m] above the sourceAltitude
44 46 48 50 52
Noise level [dBA]
South hillside L95 [dBA] –
200 [m] above the sourceAltitude
42 44 46 48 50 52
Standard profile Gradient > 1,5 Thermal Huge gradient
Noise level [dBA]
South hillside L95 [dBA] –
200 [m] above the sourceAltitude
48 50 52 54 56 58 60
Noi se le vel [dB A]
Bottom of the valley L95 [dBA]
Same altitude of the source
46 48 50 52 54 56 58 60
Standard profile Gradient > 1,5 Thermal inversion
Noi se le vel [dB A]
Bottom of the valley L95 [dBA]
Same altitude of the source
Altitude [m]
Altitude
48 50 52 54 56 58 60
Noi se le vel [dB A]
Bottom of the valley L95 [dBA]
Same altitude of the source
Altitude [m]
46 48 50 52 54 56 58 60
Standard profile Gradient > 1,5 Thermal inversion
Noi se le vel [dB A]
Bottom of the valley L95 [dBA]
Same altitude of the source
Altitude [m]
Altitude
44 46 48 50
Noise level [dBA]
City 1 L95 [dBA]
Same altitude of the source
Conclusions
Thermal inversion is a common phenomenon in Aosta Valley
Noise increase up to 10 dB
Increases are strongly influenced by the position and the altitude of the receptor
