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Jim Thomson

Senior Principal Oceanographer

Associate 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

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

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

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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

Wake measurements from a hydrokinetic river turbine

Guerra, M., and J. Thomson, "Wake measurements from a hydrokinetic river turbine," Renewable Energy, EOR, doi:10.1016/j.renene.2019.02.052, 2019.

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15 Feb 2019

During the boreal summer of 2015, a full-scale hydrokinetic turbine was deployed in the Kvichak River (Alaska), delivering electricity to the village of Igiugig. Here, quantification and analysis of the hydrodynamic modifications in the river caused by the turbine are presented. Field observations are used to produce a unique three-dimensional data set of fluid velocities in the vicinity of the turbine before and after turbine deployment. Three dynamic regions are distinguished in the wake. There is an induction zone just upstream of the turbine, where velocities decrease and turbulence increases. There is a near wake just downstream of the turbine, where the reduced velocities recover slightly and the elevated turbulence decays rapidly. Finally, there is a far wake well beyond the turbine, where reduced velocities are persistent and turbulence remains elevated. The results are used in a coarse energy budget for the river, including quantifying the total energy dissipated by turbulence in the near wake. This wake dissipation is found to be almost as large as the energy extracted for electricity generation, even when the turbine is not operational.

Overview of the Arctic Sea State and Boundary Layer Physics Program

Thomson, J., and 32 others, including L. Rainville, and M. Smith, "Overview of the Arctic Sea State and Boundary Layer Physics Program," J. Geophys. Res., 123, 8674-8687, doi:10.1002/2018JC013766, 2018.

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1 Dec 2018

A large collaborative program has studied the coupled air‐ice‐ocean‐wave processes occurring in the Arctic during the autumn ice advance. The program included a field campaign in the western Arctic during the autumn of 2015, with in situ data collection and both aerial and satellite remote sensing. Many of the analyses have focused on using and improving forecast models. Summarizing and synthesizing the results from a series of separate papers, the overall view is of an Arctic shifting to a more seasonal system. The dramatic increase in open water extent and duration in the autumn means that large surface waves and significant surface heat fluxes are now common. When refreezing finally does occur, it is a highly variable process in space and time. Wind and wave events drive episodic advances and retreats of the ice edge, with associated variations in sea ice formation types (e.g., pancakes, nilas). This variability becomes imprinted on the winter ice cover, which in turn affects the melt season the following year.

A surface kinematics buoy (SKIB) for wave–current interaction studies

Guimarães, P.V., F. Ardhuin, P. Sutherland, M. Accensi, M. Hamon, Y. Pérignon, J. Thomson, A. Benetazzo, and P. Ferrant, "A surface kinematics buoy (SKIB) for wave–current interaction studies," Ocean Sci., 14, 1449-1460, doi:10.5194/os-14-1449-2018, 2018.

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26 Nov 2018

Global navigation satellite systems (GNSSs) and modern motion-sensor packages allow the measurement of ocean surface waves with low-cost drifters. Drifting along or across current gradients provides unique measurements of wave–current interactions. In this study, we investigate the response of several combinations of GNSS receiver, motion-sensor package and hull design in order to define a prototype "surface kinematics buoy" (SKIB) that is particularly optimized for measuring wave–current interactions, including relatively short wave components that are important for air–sea interactions and remote-sensing applications. The comparison with existing Datawell Directional Waverider and Surface Wave Instrument Float with Tracking (SWIFT) buoys, as well as stereo-video imagery, demonstrates the performance of SKIB. The use of low-cost accelerometers and a spherical ribbed and skirted hull design provides acceptable heave spectra E(f) from 0.09 to 1 Hz with an acceleration noise level (2πf)4E(f) close to 0.023 m2 s-3. Velocity estimates from GNSS receivers yield a mean direction and directional spread. Using a low-power acquisition board allows autonomous deployments over several months with data transmitted by satellite. The capability to measure current-induced wave variations is illustrated with data acquired in a macro-tidal coastal environment.

More Publications

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

More News Items

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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