Long term estimations of low frequency noise levels over water from an off-shore wind farm

Abstract

This article focuses on computations of low frequency sound propagation from an off-shore wind farm. Two different methods for sound propagation calculations are combined with meteorological data for every 3 hours in the year 2010 to examine the varying noise levels at a reception point at 13 km distance. It is shown that sound propagation conditions play a vital role in the noise impact from the off-shore wind farm and ordinary assessment methods can become inaccurate at longer propagation distances over water. Therefore, this paper suggests that methodologies to calculate noise immission with realistic sound speed profiles need to be combined with meteorological data over extended time periods to evaluate the impact of low frequency noise from modern off-shore wind farms.

Atmospheric Sound Propagation over Rough Sea: Numerical Evaluation of Equivalent Acoustic Impedance of Varying Sea States

“…Figure8compares equivalent impedances obtained in this work with those reported by Bolin et al[6,7] and Van Renterghem et al[8]. Bolin et al limited the analysis to discrete frequencies of 80, 200, and 400 Hz.…”

“…Different approaches for estimating the equivalent impedance of a rough sea surface have been adopted by Boulanger and Attenborough [20], Bolin et al [6,7], and Van Renterghem et al [8]. The method proposed by Boulanger and Attenborough is the same as that implemented in the work of Van Renterghem et al However, the results from Boulanger and Attenborough are not used for comparison as they have been obtained using surfaces that are not derived from sea state spectra.…”

“…The value of Z s corresponding to 80 Hz is not reported in Figure 8, as it is outside the range of frequencies considered in this work. Additionally, the significant wave height H s was not measured during the experiments, and thus, the relative sea state is not reported in [6,7] and Van Renterghem et al [8]. Note that the y-axis is on a logarithmic scale.…”

“…Sound propagation predictions obtained with a PE solver were compared to long range acoustic measurements (9 km of open water and 750 m of land). A constant effective flow resistivity of 3 × 10 4 kPa s m −2 was chosen to represent rough water independently of the sea state [7].…”

“…For many decades, atmospheric sound propagation studies have been conducted predominantly on land [1][2][3][4], with only a few studies conducted over sea and small bodies of water [5]. In recent years, research on sound propagation in coastal areas has garnered increased interest, driven by the growth of off-shore wind farms [6][7][8], oil and gas platforms, offshore airport construction [9], and other activities. However, the study of sound propagation over the sea is also critical for the detection of vessels at sea in cases of low visibility at ranges on the order of kilometers.…”