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Jacob Davis

Research Assistant




2000-present and while at APL-UW

Development and testing of microSWIFT expendable wave buoys

Thomson, J., P. Bush, V.C. Contreras, N. Clemett, J. Davis, A. de Klerk, E. Iseley, E.J. Rainville, B. Salmi, and J. Talbert, "Development and testing of microSWIFT expendable wave buoys," Coastal Eng. J., EOR, doi:10.1080/21664250.2023.2283325, 2023.

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22 Nov 2023

Expendable microSWIFT buoys have been developed and tested for measuring ocean surface waves. Wave spectra are calculated via onboard processing of GPS velocities sampled at 5 Hz, and wave spectra are delivered to a shore-side server via Iridium modem once per hour. The microSWIFTs support additional sensor payloads, in particular seawater conductivity and temperature. The buoys have a non-traditional, cylindrical shape that is required for deployment via the dropsonde tube of research aircraft. Multiple versions have been developed and tested, with design considerations that include: buoy hydrodynamics, sensor noise, algorithm tuning, processor power, and ease of deployment. Field testing in a range of conditions, including near sea ice and in a hurricane, has validated the design.

Observations of ocean surface wave attenuation in sea ice using seafloor cables

Smith, M.M., J. Thomson, M.G. Baker, R.E. Abbott, and J. Davis, "Observations of ocean surface wave attenuation in sea ice using seafloor cables," Geophys. Res. Lett., 50, doi:10.1029/2023GL105243, 2023.

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28 Oct 2023

The attenuation of ocean surface waves during seasonal ice cover is an important control on the evolution of Arctic coastlines. The spatial and temporal variations in this process have been challenging to resolve with conventional sampling using sparse arrays of moorings or buoys. We demonstrate a novel method for persistent observation of wave-ice interactions using distributed acoustic sensing (DAS) along existing seafloor fiber optic telecommunications cables. DAS measurements span a 36-km cross-shore cable on the Beaufort Shelf from Oliktok Point, Alaska. DAS optical sensing of fiber strain-rate provides a proxy for seafloor pressure, which we calibrate with wave buoy measurements during the ice-free season (August 2022). We apply this calibration during the ice formation season (November 2021) to obtain unprecedented resolution of variable wave attenuation rates in new, partial ice cover. The location and strength of wave attenuation serve as proxies for ice coverage and thickness, especially during rapidly evolving events.

Saturation of ocean surface wave slopes observed during hurricanes

Davis, J.R., J. Thomson, I.A. Houghton, J.D. Doyle, W.A. Komaromi, C.W. Fairall, E.J. Thompson, and J.R. Moskaitis, "Saturation of ocean surface wave slopes observed during hurricanes," Geophys. Res. Lett., 50, doi:10.1029/2023GL104139, 2023.

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28 Aug 2023

Drifting buoy observations of ocean surface waves in hurricanes are combined with modeled surface wind speeds. The observations include targeted aerial deployments into Hurricane Ian (2022) and opportunistic measurements from the Sofar Ocean Spotter global network in Hurricane Fiona (2022). Analysis focuses on the slope of the waves, as quantified by the spectral mean square slope. At low-to-moderate wind speeds (<15 ms-1), slopes increase linearly with wind speed. At higher winds (>15 ms-1), slopes continue to increase, but at a reduced rate. At extreme winds (>30 ms-1), slopes asymptote. The mean square slopes are directly related to the wave spectral shapes, which over the resolved frequency range (0.03–0.5 Hz) are characterized by an equilibrium tail (f-4) at moderate winds and a saturation tail (f-5) at higher winds. The asymptotic behavior of wave slope as a function of wind speed could contribute to the reduction of surface drag at high wind speeds.

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center