Skip to content

Meteorology

Since wind direction and wind speed influence the sound propagation, these parameters are either taken into account in the calculation or are already part of the calculation model’s basic assumptions.

The calculation method in ISO 9613-2 calculates the equivalent continuous A-weighted sound pressure level for downwind conditions of propagation (for detailed definition see ISO 9613-2, section 5). These meteorological conditions represent a favorable propagation situation where for source-receiver combination (acoustic ray) slight downwind is assumed.

To correct for wind situations deviating from this assumption the so-called „meteorological correction“ Cmet is used. According to ISO 9613-2 (1996), equation (6), it holds:

\(L_{AT}(LT)=L_{AT}(DW)-C_{met}\)

where

  • LAT(LT): long-term average A-weighted sound pressure level for the meteorological situation under consideration (LT=long-term),
  • LAT(DW): equivalent continuous A-weighted sound pressure level for downwind conditions (DW=downwind),
  • Cmet: meteorological correction.

Correction Cmet

The calculation according to ISO 9613-2 (1996), section 8, is as follows:

\(C_{met} = C_0[1-\frac{10(h_s+h_r)}{d_p}]\)

for \(d_p > 10(h_s+h_r)\),

else \(C_{met}=0\).

Where

-  C<sub>0</sub>: correction factor in dB,
-  h<sub>s</sub>: source height above ground, in meters,
-  h<sub>r</sub>: receiver height above ground, in meters,
- d<sub>p</sub>: distance source-receiver projected to the horizontal ground plane.