Nathan Laxague
Assistant Professor of Ocean Engineering
Dept. of Mechanical Engineering
University of New Hampshire
Abstract
Ocean surface waves are essential mediators of atmosphere-ocean interactions, facilitating the transfer of momentum, heat, and gas across the air-sea interface. Short wind-generated surface waves with lengths of order 1 m and smaller are most closely associated with these fluxes. However, the most commonly-used ocean wave measurement techniques (buoys, fixed gauges, ADCPs, etc.) are not able to resolve these short waves. In this presentation I will describe my group's recent advancements in the measurement of wind-generated ocean surface waves ranging in length from sub-centimeter to tens of meters. These use polarimetric imaging of the sea surface, extended to recover both the short waves resolved within a single frame and the longer waves that merely pass through it, to quantify the directional behavior of wind waves from the equilibrium to the gravity-capillary regime, capturing the broadening of the directional distribution above the spectral peak and its return to a narrow, downwind lobe at centimeter scales. I will also describe extension of this work to a novel airborne platform and the means by which residual platform motion is separated from wave motion, allowing for computation of the wavenumber-frequency spectrum. Flown at a range of altitudes over a single site, the system returns a directional spectrum spanning nearly three decades of wavenumber in which wavenumber and frequency are measured independently, so that the we may directly measure free waves, bound harmonics, and near-surface currents. I will close the presentation with a description of the tandem airborne/in situ/scanning LiDAR measurement capabilities developed in my group which enable extended-duration process studies of targeted physical processes.
Bio
Nathan Laxague received his Ph.D. in 2016 from the Rosenstiel School of Marine and Atmospheric Science at the University of Miami. He was a postdoctoral research scientist at Lamont-Doherty Earth Observatory of Columbia University from 2017-2020. Since 2020, he has been an Assistant Professor of Ocean Engineering in the Department of Mechanical Engineering at the University of New Hampshire. Prof. Laxague makes field and laboratory measurements to explore the physical interactions between the Earth’s atmosphere and oceans. He is particularly interested in the role of ocean surface waves in mediating air-sea fluxes.
