Seismo Lab Seminar

Ocean surface oscillations with frequencies 0.003 to 20 Hz are related surface gravity-capillary waves generated by the wind. The growth of these wind-waves is slow as energy from the wind is continuously lost to ocean turbulence due to wave breaking, and energy slowly builds up at lower and lower frequencies thanks to wave-wave interactions. As a result the wave field properties are a low-pass filter of the wind fields, with distinct behaviours at different frequencies, influenced by ocean currents, sea ice and bathymetry as the waves propagate across ocean basins. Most of the evolution processes for the wave energy cannot yet be described from first principles and numerical wave models use parameterization recipes that aim to mimick the evolution of wave spectra. These models were initially developed for marine meteorology with a strong focus on E the total wave energy per unit surface, or equivalently the significant wave height defined as 4 times the square root of E. In the past 15 years, following the paper by Sharon Kedar, I have made efforts to improve on wave models to compute sources of microseisms and microbaroms. My original goal was to constrain some parts of the wave spectrum that could not be measured by existing instruments (satellites and in situ buoys): I introduced a very crude representation of coastal reflection, wave-ice interactions, investigated wave-current interactions. Over the last 2 years we finally managed to reproduce some of the high frequency ( f > 0.4 Hz) behaviour for which ocean bottom acoustic data was critical, and we are now getting unprecedented views of ocean waves from space using the SAR interferometer on the SWOT satellite. Probably we are going to learn a lot from DAS data in the coming years. How can we use all these new data sources to improve on our understanding of ocean wave properties and their role as microseism sources?