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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

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.

Wave Measurements at Ocean Weather Station PAPA

As part of a larger project to understand the impact of surface waves on the ocean mixed layer, APL-UW is measuring waves at Ocean Weather Station Papa, a long-term observational site at N 50°, W 145°.

29 Aug 2019

Coastal Ocean Dynamics in the Arctic — CODA

Arctic coastlines are eroding at rates of meters per year. As the whole Arctic shifts into a modern epoch of seasonal ice cover and warmer temperatures, Arctic coastal processes are shifting, too. The overall goal of this research is to improve scientific understanding of wave–ice–ocean interactions along the Arctic coast, with particular attention to the oceanographic parameters that affect erosion.

8 Jan 2019

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Videos

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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Publications

2000-present and while at APL-UW

Wave groups observed in pancake sea ice

Thomson, J., J. Gemmrich, W.E. Rogers, C.O. Collins, and F. Ardhuin, "Wave groups observed in pancake sea ice," J. Geophys. Res., EOR, doi:10.1029/2019JC015354, 2019.

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16 Oct 2019

Ocean surface waves propagating through sea ice are scattered and dissipated. The net attenuation occurs preferentially at the higher frequencies, and thus the spectral bandwidth of a given wave field is reduced, relative to open water. The reduction in bandwidth is associated with an increase in the groupiness of the wave field. Using SWIFT buoy data from the 2015 Arctic Sea State experiment, bandwidth is compared between pancake ice and open water conditions, and the linkage to group envelopes is explored. The enhancement of wave groups in ice is consistent with the simple linear mechanism of superposition of waves with narrowing spectral bandwidth. This is confirmed using synthetic data. Nonlinear mechanisms, which have been shown as significant in other ice types, are not found to be important in this data set.

Breaking waves in deep water: Measurements and modeling of energy dissipation

Rollano, F.T., A. Brown, A. Ellenson, H.T. Özkan-Haller, J. Thomson, and M.C. Haller, "Breaking waves in deep water: Measurements and modeling of energy dissipation," Ocean Dyn., 69, 1165-1179, doi:10.1007/s10236-019-01301-2, 2019.

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1 Oct 2019

In the presence of strong winds, ocean surface waves dissipate significant amounts of energy by breaking. Here, breaking rates and wave-following turbulent dissipation rate measurements are compared with numerical WAVEWATCH III estimates of bulk energy dissipation rate. At high winds, the measurements suggest that turbulent dissipation becomes saturated; however, the modeled bulk dissipation continues to increase as a cubic function of wind speed. Similarly, the mean square slope (i.e., the steepness) of the measured waves becomes saturated, while the modeled mean squared slope grows linearly with wind speed. Only a weak relation is observed between breaker fraction and wind speed, possibly because these metrics do not capture the scale (e.g., crest length) of the breakers. Finally, the model skill for basic parameters such as significant wave height is shown to be sensitive to the dissipation rate, indicating that the model skill may be compromised under energetic conditions.

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., 44, 1011-1023, doi:10.1109/JOE.2018.2868335, 2019.

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1 Oct 2019

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.

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In The News

Fall storms, coastal erosion focus of northern Alaska research cruise

UW News, Hannah Hickey

A University of Washington team is leaving to study how fall storms, dwindling sea ice and vulnerable coastlines might combine in a changing Arctic. The project leaves Thursday, Nov. 7, from Nome, Alaska in the Bering Strait to spend four weeks gathering data during the fall freeze-up season.

5 Nov 2019

UW team sending autonomous surfboard to explore Antarctic waters

UW News, Hannah Hickey

The research project will use the Wave Glider to investigate the summer conditions near Palmer Station on the Antarctic Peninsula, to better understand how the warming ocean interacts with ice shelves that protrude from the shore. It will then head across Drake Passage, braving some of the stormiest seas on the planet.

23 Oct 2019

Public talks kick off study of ice loss, warming and coastal changes in northern Alaska

UW News

The northernmost town in the country had its warmest March on record. Utqiagvik, formerly known as Barrow, is among the coastal communities that are feeling the effects of a warming Arctic firsthand.

25 Apr 2019

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Inventions

SWIFT v4

Record of Invention Number: 48200

Jim Thomson, Alex de Klerk, Joe Talbert

Disclosure

6 Nov 2017

SWIFT: Surface Wave Instrument Float with Tracking

Record of Invention Number: 46566

Jim Thomson, Alex De Klerk, Joe Talbert

Disclosure

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

Disclosure

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
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