Statistical Analysis of Wind- and Rain-generated Ocean Ambient Noise in the Northeast Pacific Continental Margin

Abstract

Large scale studies of underwater ambient noise during wind and rain are important for assessing the ocean environment and enabling remote sensing of wind speeds and rain rates over the open ocean. In this work, approximately 3.5 years of acoustical and meteorological data recorded at the northeast Pacific continental margin are evaluated. The acoustic data are recorded at a sampling rate of 64 kHz and depths of 81 m and 581 m at the continental shelf and slope, respectively. Rain rates and wind speeds are provided by surface buoys located in the vicinity of each hydrophone. Acoustic and meteorological data are used to compute power spectral density (PSD) estimates for various wind speeds and rain rates. Since the acoustic data are compromised by outliers, a robust spectral estimator that uses sample percentiles is introduced and its statistical properties are derived. The resulting PSD estimates are used to analyze and model the frequency, wind speed, and rain rate dependency of ambient noise spectral levels in greater detail. Furthermore, the results are compared with findings from previous studies.