Relation between ocean wave activity and wavefield of the ambient noise recorded in northern Poland
- PDF / 17,013,772 Bytes
- 20 Pages / 547.087 x 737.008 pts Page_size
- 44 Downloads / 169 Views
ORIGINAL ARTICLE
Relation between ocean wave activity and wavefield of the ambient noise recorded in northern Poland Simone Lepore & Marek Grad
Received: 12 September 2019 / Accepted: 14 October 2020 # The Author(s) 2020
Abstract The temporal and spatial variations of the wavefield of ambient noise recorded at ‘13 BB star’ array located in northern Poland were related to the activity of high, long-period ocean waves generated by strong storms in the Northern Indian Ocean, the Atlantic Ocean, and the Northern Pacific Ocean between 2013 and 2016. Once pre-processed, the raw noise records in time- and frequency-domains, and spectral analysis and high-resolution three-component beamforming techniques were applied to the broadband noise data. The power spectral density was analysed to quantify the noise wavefield, observing the primary (0.04–0.1 Hz) microseism peak and the splitting of the secondary microseism into longperiod (0.2–0.3 Hz) and short-period (0.3–0.8 Hz) peaks. The beam-power analysis allowed to determine the changes in the azimuth of noise sources and the velocity of surface waves. The significant wave height, obtained by combining observed data and forecast model results for wave height and period, was analysed to characterise ocean wave activity during strong storms. The comparison of wave activity and beam-power led to distinguish the sources of Rayleigh and Love waves associated to long-period
Prof. Grad died suddenly during the revision process. The present work is dedicated to his memory. S. Lepore (*) : M. Grad Institute of Geophysics Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland e-mail: [email protected]
microseisms, of short-period microseisms, and of primary microseisms. High, long-period ocean waves hitting the coastline were found to be the main source of noise wavefield. The source of long-period microseisms was correlated to such waves in the open sea able to reach the shore, whereas the source of primary microseisms was tied to waves interacting with the seafloor very close to the coastlines. The source of short-period microseisms was attributed to strong storms constituted of short-period waves not reaching the coast. Keywords Ambient noise . Ocean wave activity . Primary and secondary microseisms . Numerical modelling . Beamforming
1 Introduction The description of spatial and temporal variations of the ambient noise wavefield is fundamental for many aspects of seismology. Ambient noise can be used not only to infer the characteristics of ocean storms (Ebeling 2012), but also to evaluate the performance of seismic arrays (Wilson et al. 2002) and to investigate the Earth’s structure (Shapiro and Campillo 2004; Sabra et al. 2005; Lepore and Grad, 2018). Temporal changes of the noise wavefield during strong ocean storms are consistent with the variations in the wave height and wavewave interaction (Friedrich et al. 1998; Nishida et al. 2008; Ardhuin et al. 2011, 2015; Obrebski et al.
J Seismol
2012; Davy et al. 2015; Möllhoff and Bean 2016).
Data Loading...
