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Jim Thomson

Senior Principal Oceanographer

Associate Professor, Civil and Environmental Engineering





Research Interests

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


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


B.A. Physics, Middlebury College, 2000

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


Stratified Ocean Dynamics of the Arctic — SODA

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31 Oct 2016

Vertical and lateral water properties and density structure with the Arctic Ocean are intimately related to the ocean circulation, and have profound consequences for sea ice growth and retreat as well as for prpagation of acoustic energy at all scales. Our current understanding of the dynamics governing arctic upper ocean stratification and circulation derives largely from a period when extensive ice cover modulated the oceanic response to atmospheric forcing. Recently, however, there has been significant arctic warming, accompanied by changes in the extent, thickness distribution, and properties of the arctic sea ice cover. The need to understand these changes and their impact on arctic stratification and circulation, sea ice evolution, and the acoustic environment motivate this initiative.

Inner Shelf Dynamics

The inner shelf region begins just offshore of the surf zone, where breaking by surface gravity waves dominate, and extends inshore of the mid-shelf, where theoretical Ekman transport is fully realized. Our main goal is to provide provide improved understanding and prediction of this difficult environment. This will involve efforts to assess the influence of the different boundaries — surf zone, mid and outer shelf, air-water interface, and bed — on the flow, mixing and stratification of the inner shelf. We will also gain information and predictive understanding of remotely sensed surface processes and their connection to processes in the underlying water column.

15 Dec 2015

Measuring Vessel Wakes in Rich Passage, Puget Sound

APL-UW is using wave buoys to measure the wakes of Washington State DOT car ferries as they transit through Rich Passage. The objective is to assess the effectiveness of the speed reduction protocol through the passage, which is intended to minimize the vessel wake and minimize any subsequent changes to the shoreline.

22 Oct 2014

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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.

Marine Renewable Energy: Kvichak River Project

At a renewable energy site in the village of Igiugig, Alaska, an APL-UW and UW Mechanical Engineering team measured the flow around an electricity-generating turbine installed in the Kvichak River. They used modified SWIFT buoys and new technologies to measure the natural river turbulence as well as that produced by the turbine itself. The turbine has the capacity to generate a sizable share of the village's power needs.

25 Sep 2014

Ferry-Based Monitoring of Puget Sound Currents

Acoustic Doppler Current Profilers are installed on two Washington State Department of Transportation ferries to measure current velocities in a continuous transect along their routes. WSDOT ferries occupy strategic cross-sections where circulation and exchange of Puget Sound and Pacific Ocean waters occurs. A long and continuous time series will provide unprecedented measurements of water mass movement and transport between the basins.

9 May 2014

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2000-present and while at APL-UW

Kinematics and statistics of breaking waves observed using SWIFT buoys

Brown, A., J. Thomson, A. Ellenson, F.T. Rollano, H.T. Özkan-Haller, and M.C. Haller, "Kinematics and statistics of breaking waves observed using SWIFT buoys," IEEE J. Ocean. Eng., EOR, doi:10.1109/JOE.2018.2868335, 2018.

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10 Oct 2018

Surface wave instrumentation floats with tracking were deployed by helicopter ahead of five large storms off the Oregon coast. The buoys drifted freely with the wave motions, surface currents, and wind. The buoys use a 9-DoF inertial measurement unit that fuses the measurements of accelerometers, magnetometers, and gyroscopes to measure acceleration in the global North-West-Up reference frame. Rapid sampling (25 Hz) allows for the observation of both propagating wave motions and wave breaking events. Bulk wave parameters and wave spectra are calculated from the motion of the buoys using conventional methods, and breaking wave impacts are identified in the raw acceleration data using a new algorithm based on a short-time Fourier transform. The number of breaking waves is used to infer breaker fraction, which is found to depend on bulk wave steepness as previously shown in the literature. The magnitude and duration of acceleration during breaking is used in a new quantification of breaker intensity, which increases with wave height, period, and steepness. There is significant variance of breaker intensity in a given wave field, such that intense breakers still occur in relatively mild wave fields. The buoy observations are compared to the output of the WaveWatch III forecast model, with evaluation of an empirical breaker prediction scheme applied to WaveWatch III output.

Hydrodynamic coefficients of heave plates, with application to wave energy conversion

Brown, A., J. Thomson, and C. Rusch, "Hydrodynamic coefficients of heave plates, with application to wave energy conversion," IEEE J. Ocean. Eng., 43, 983-996, doi:10.1109/JOE.2017.2762258, 2018.

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1 Oct 2018

Wave energy converters (WECs) often employ submerged heave plates to provide reaction forces at depths below the level of wave motion. Here, two sets of heave plate experiments are described, at varying scale. First, the Oscillator uses a linear actuator to force laboratory scale (30.5-cm diameter) heave plates in sinusoidal motion. Second, the miniWEC buoy uses vessel wakes to force field scale (1.5-m diameter) heave plates in open water with realistic energy conversion (damping). The motion and forces are analyzed using the Morison equation, in which the hydrodynamic coefficients of added mass CM and drag CD are determined for each set of Oscillator and miniWEC experiments. Results show strong intracycle variations in these coefficients, yet constant hydrodynamic coefficients provide a reasonable reconstruction of the time series data. The two test scales are examined relative to the Keulegan–Carpenter number (KC), Reynold's number (Re), and Beta number (β). The effects of asymmetric shape on hydrodynamic performance are found to be small.

The influence of wind and waves on spreading and mixing in the Fraser River plume

Kastner, S.E., A.R. Horner-Devine, and J. Thomson, "The influence of wind and waves on spreading and mixing in the Fraser River plume," J. Geophys. Res., 123, 6818-6840, doi:10.1029/2018JC013765, 2018.

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5 Sep 2018

This study uses drifter‐based observations to investigate the role of wind and waves on spreading and mixing in the Fraser River plume. Local winter wind patterns commonly result in two distinct forcing conditions, moderate winds from the southeast (SE) and strong winds from the northwest (NW). We examine how these patterns influence the spreading and mixing dynamics of the plume. Under SE winds, the plume thins, spreads, and turns to the right (north) upon exiting the river mouth. Mixing is initially intense in the region of maximum spreading, but it is short‐lived. Under NW winds, which oppose the rightward tendency of the plume, the plume remains thicker, narrower, and flows directly across the Strait with a lateral front on its northern side. Mixing is initially lower than under SE forcing but persists further across the Strait. A Lagrangian stream‐normal momentum balance shows that wind and interfacial stress under NW conditions compress the sea surface height anomaly formed by the river discharge and guide the flow across the Strait. This reconfiguration changes spreading and mixing dynamics of the plume; plume spreading, which drives intense mixing under SE winds, is shut down under NW winds, and mixing rates are consequently much lower. Despite the initially lower mixing rates, the region of active mixing extends further under NW winds, resulting in higher net mixing. These results highlight that the wind, which is often a primary cause of increased plume mixing, can also significantly influence mixing by changing the geometry of the plume.

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In The News

State investigators focus on nets plugged with mussels in Atlantic salmon net-pen failure

The Seattle Times, Lynda Mapes

Cooke Aquaculture’s maintenance practices at its collapsed Atlantic salmon farm at Cypress Island have drawn the attention of state investigators after nets were found fouled with mussels and other sea life. Fluid mechanics expert Jim Thomson notes that nets clogged with sea life create greater drag forces in the ocean currents, increasing the risk of structural failure.

26 Jan 2018

Partners in Extreme Wave Modeling

Engineering Out Loud Podcast, Jens Odegaard

How do you forecast and model huge waves in the open ocean? As part of the National Marine Renewable Energy Center, researchers at Oregon State University and the University of Washington are modeling and forecasting extreme waves to help inform wave energy technology.

25 Oct 2017

Wave Glider surfs across stormy Drake Passage in Antarctica

UW News, Hannah Hickey

The University of Washington sent a robotic surf board to ride the waves collecting data from Antarctica to South America.

20 Sep 2017

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Record of Invention Number: 48200

Jim Thomson, Alex de Klerk, Joe Talbert


6 Nov 2017

SWIFT: Surface Wave Instrument Float with Tracking

Record of Invention Number: 46566

Jim Thomson, Alex De Klerk, Joe Talbert


24 Jun 2013

Heave Place Mooring for Wave Energy Conversion (WEC) via Tension Changes

Record of Invention Number: 46558

Jim Thomson, Alex De Klerk, Joe Talbert


19 Jun 2013

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