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Jim Thomson

Senior Principal Oceanographer

Professor, Civil and Environmental Engineering

Email

jthomson@apl.washington.edu

Phone

206-616-0858

Research Interests

Environmental Fluid Mechanics, Ocean Surface Waves, Marine Renewable Energy (tidal and wave), Coastal and Nearshore Processes, Ocean Instrumentation

Biosketch

Dr. Thomson studies waves, currents, and turbulence by combining field observations and remote sensing techniques

Education

B.A. Physics, Middlebury College, 2000

Ph.D. Physical Oceanography, MIT/WHOI, 2006

Projects

Persistent Measurements of Surface Waves in Landfast Ice Using Fiber Optic Telecommunication Cables

The high-resolution data collected during this research will help address fundamental questions about wave attenuation in landfast ice and breakup. The research is motivated by two questions: (1) What is the spatial and temporal variability of wave attenuation in landfast sea ice? (2) What drives landfast breakup? (Collaborative research with M. Smith, WHOI)

30 Aug 2023

Hurricane Coastal Impacts

APL-UW scientists are collaborating with 10 research teams to tackle the National Oceanographic Partnership Program (NOPP) project goals: to enable better understanding and predictive ability of hurricane impacts, to serve and protect coastal communities. The APL-UW team will contribute air-deployed buoys to provide real time observations of hurricane waves and wave forcing that can be ingested by modeling groups, improving forecasts and validating hindcasts.

14 Dec 2021

Wave Glider Observations in the Southern Ocean

A Wave Glider autonomous surface vehicle will conduct a summer-season experiment to investigate ocean–shelf exchange on the West Antarctic Peninsula and frontal air–sea interaction over both the continental shelf and open ocean.

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4 Sep 2019

Southern Ocean climate change is at the heart of the ocean's response to anthropogenic forcing. Variations in South Polar atmospheric circulation patterns, fluctuations in the strength and position of the Antarctic Circumpolar Current, and the intertwining intermediate deep water cells of the oceanic meridional overturning circulation have important impacts on the rate of ocean carbon sequestration, biological productivity, and the transport of heat to the melting continental ice shelves.

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Videos

microSWIFTs: Tiny Oceanographic Floats Measure Extreme Coastal Conditions

These small, inexpensive ocean drifters are the latest generation of the Surface Wave Instrument Float with Tracking (SWIFT) platform developed at APL-UW. They are being used in several collaborative research experiments to increase the density of nearshore wave observations.

19 Apr 2022

Using a Wave Energy Converter for UUV Recharge

This project demonstrates the interface required to operate, dock, and wirelessly charge an uncrewed underwater vehicle with a wave energy converter.

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11 Apr 2022

Uncrewed underwater vehicles (UUVs) predominantly use onboard batteries for energy, limiting mission duration based on the amount of stored energy that can be carried by the vehicle. Vehicle recharge requires recovery using costly, human-supported vessel operations. The ocean is full of untapped energy in the form of waves that, when converted to electrical energy by a wave energy converter (WEC), can be used locally to recharge UUVs without human intervention. In this project we designed and developed a coupled WEC-UUV system, with emphasis on the systems developed to interface the UUV to the WEC.

Mapping Underwater Turbulence with Sound

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9 Apr 2018

To dock at a terminal, large Washington State ferries use their powerful engines to brake, generating a lot of turbulence. Doppler sonar instruments are capturing an accurate picture of the turbulence field during docking procedures and how it affects terminal structures and the seabed. This research is a collaborative effort between APL-UW and the UW College of Engineering, Department of Civil and Environmental Engineering.

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Publications

2000-present and while at APL-UW

Measurements of nearshore ocean-surface kinematics through coherent arrays of free-drifting buoys

Rainville, E., J. Thomson, M. Moulton, and M. Derakhti, "Measurements of nearshore ocean-surface kinematics through coherent arrays of free-drifting buoys," Earth Syst. Sci. Data, 15, 5135-5151, doi:10.5194/essd-15-5135-2023, 2023.

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27 Nov 2023

Surface gravity wave breaking occurs along coastlines in complex spatial and temporal patterns that significantly impact erosion, scalar transport, and flooding. Numerical models are used to predict wave breaking and associated processes but many lack sufficient evaluation with observations. To fill the need for more nearshore wave measurements, we deployed coherent arrays of small-scale, free-drifting buoys named microSWIFTs. The microSWIFT is a small buoy equipped with a GPS module to measure the buoy's position, horizontal velocities, and an inertial measurement unit (IMU) to directly measure the buoy's rotation rates, accelerations, and heading. Measurements were collected over a 27 d field experiment in October 2021 at the US Army Corps of Engineers Field Research Facility in Duck, NC. The microSWIFTs were deployed as a series of coherent arrays, meaning they all sampled simultaneously with a common time reference, leading to a rich spatial and temporal dataset during each deployment. Measurements spanned offshore significant wave heights ranging from 0.5 to 3 m and peak wave periods ranging from 5 to 15 s over the entire experiment.

The completed dataset consists of 67 deployment files that contain 971 drift tracks that contain all associated data. We use an attitude and heading reference system (AHRS) 9-degrees-of-freedom Kalman filter to rotate the measured accelerations from the reference frame of the buoy to the Earth reference frame. We then use the corrected accelerations to compute the vertical velocity and sea-surface elevation. We give example evaluations of wave spectral energy density estimates from individual microSWIFTs compared with a nearby acoustic wave and current (AWAC) sensor. A zero-crossing algorithm is applied to each buoy time series of sea-surface elevation to extract realizations of measured surface gravity waves, yielding 116 307 wave realizations throughout the experiment. We also compute significant wave height estimates from the aggregate wave realizations and compare these estimates with the nearby AWAC estimates. An example of spatial variability in cross-shore velocity and vertical acceleration is explored. Wave-breaking events, detected by high-intensity vertical acceleration peaks, are explored, and the cross-shore distribution of all breaking events detected in the experiment is shown. A total of 3419 wave-breaking events were detected across the entire experiment. These data are available at https://doi.org/10.5061/dryad.hx3ffbgk0 (Rainville et al., 2023) and will be used to investigate nearshore wave kinematics, transport of buoyant particles, and wave-breaking processes.

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.

Acoustic backscattering at a tidal intrusion front

Bassett, C., and 9 others including J. Thomson, "Acoustic backscattering at a tidal intrusion front," Prog. Oceanogr., EOR, doi:10.1016/j.pocean.2023.103167, 2023.

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8 Nov 2023

Strong spatial gradients and rapidly evolving, three-dimensional structure make estuarine fronts difficult to sample. Echosounders can be used near fronts to provide nearly synoptic images of water column processes and, with sufficient bandwidth, can provide quantitative information about dynamical variables derived from forward and inverse methods using acoustic backscattering measurements. This manuscript discusses measurements using broadband (50-420 kHz) echosounders from the James River (Virginia, USA) tidal intrusion front. The dominant backscattering mechanisms observed at the site include bubbles, turbulent microstructure, interfaces associated with stratification, suspended sediment, and biota. Existing analytical models are used to interpret contributions from these sources with acoustic inversions providing quantitative information about the physical structure and processes that compare favorably with conventional, in situ measurements. Supporting data sets for this analysis include measurements of temperature, salinity, velocity, and turbidity; X-band radar images of sea surface roughness; aerial optical imagery; Lagrangian measurements of waves, turbulence, and velocity structure; and Regional Ocean Modeling System circulation model simulations. A notable advantage of acoustic remote sensing is the ability to resolve processes at considerably higher spatial resolution (< 1 m horizontal; < 5 cm vertical) than other in situ sampling approaches.

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In The News

UW-developed wave sensors deployed to improve hurricane forecasts

UW News

Jacob Davis, a UW doctoral student in civil and environmental engineering, and members of the U.S. Navy’s VXS-1 Squadron deployed wave sensing buoys in the path of Hurricane Ian, before the hurricane made landfall.

28 Sep 2022

See delicate rib vortices encircle breaking ocean waves

Scientific American, Joanna Thompson

These little-studied mini twisters form beautiful loops under the water’s surface. Until the past decade or so few people in the scientific community paid much attention to rib vortices, partly because they are difficult to photograph. The ephemeral twists require a high-resolution camera and precise timing to capture.

1 Aug 2022

U.S. icebreaker gap with Russia a growing concern as Arctic 'cold war' heats up

Washington Times, Mike Glenn

Warming trends have spurred a chase for trade routes, natural resources at top of the world. Vessels like the Healy and the Polar Star are the most effective tools for maintaining access to the icy regions for scientific, economic and security purposes, advocates say.

23 Sep 2021

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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
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