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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

A unified breaking onset criterion for surface gravity water waves in arbitrary depth

Derakhti, M., J.T. Kirby, M.L. Banner, S.T. Grilli, and J. Thomson, "A unified breaking onset criterion for surface gravity water waves in arbitrary depth," J. Geophys. Res., 125, doi:10.1029/2019JC015886

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1 Jul 2020

We investigate the validity and robustness of the Barthelemy et al. (2018, https://doi.org/10.1017/jfm.2018.93) wave‐breaking onset prediction framework for surface gravity water waves in arbitrary water depth, including shallow water breaking over varying bathymetry. We show that the Barthelemy et al. (2018) breaking onset criterion, which they validated for deep and intermediate water depths, also segregates breaking crests from nonbreaking crests in shallow water, with subsequent breaking always following the exceedance of their proposed generic breaking threshold. We consider a number of representative wave types, including regular, irregular, solitary, and focused waves, shoaling over idealized bed topographies including an idealized bar geometry and a mildly to steeply sloping planar beach. Our results show that the new breaking onset criterion is capable of detecting single and multiple breaking events in time and space in arbitrary water depth. Further, we show that the new generic criterion provides improved skill for signaling imminent breaking onset, relative to the available kinematic or geometric breaking onset criteria in the literature. In particular, the new criterion is suitable for use in wave‐resolving models that cannot intrinsically detect the onset of wave breaking.

The evolution of a shallow front in the Arctic marginal ice zone

Brenner, S., L. Rainville, J. Thomson, and C. Lee, "The evolution of a shallow front in the Arctic marginal ice zone," Elem. Sci. Anth., 8, doi:10.1525/elementa.413, 2020.

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4 May 2020

The high degree of heterogeneity in the ice–ocean–atmosphere system in marginal ice zones leads to a complex set of dynamics which control fluxes of heat and buoyancy in the upper ocean. Strong fronts may occur near the ice edge between the warmer waters of the ice-free regions and the cold, fresh waters near and under the ice. This study presents observations of a well-defined density front located along the ice edge in the Beaufort Sea. The evolution of the front over a ~3-day survey period is captured by multiple cross-front sections measured using an underway conductivity–temperature–depth system, with simultaneous measurements of atmospheric forcing. Synthetic aperture radar images bookending this period show that the ice edge itself underwent concurrent evolution. Prior to the survey, the ice edge was compact and well defined while after the survey it was diffuse and filamented with coherent vortical structures. This transformation might be indicative of the development an active ocean eddy field in the upper ocean mixed layer. Over the course of hours, increasing wind stress is correlated with changes to the lateral buoyancy gradient and frontogenesis. Frontal dynamics appear to vary from typical open-ocean fronts (e.g., here the frontogenesis is linked to an "up-front" wind stress). Convective and shear-driven mixing appear to be unable to describe deepening at the heel of the front. While there was no measurable spatial variation in wind speed, we hypothesize that spatial heterogeneity in the total surface stress input, resulting from varying ice conditions across the marginal ice zone, may be a driver of the observed behaviour.

Sparse sampling of intermittent turbulence generated by breaking surface waves

Derakhti, M., J. Thomson, and J.T. Kirby, "Sparse sampling of intermittent turbulence generated by breaking surface waves," J. Phys. Oceanogr., 50, 867-885, doi:10.1175/JPO-D-19-0138.1, 2020.

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1 Apr 2020

We examine how Eulerian statistics of wave breaking and associated turbulence dissipation rates in a field of intermittent events compare with those obtained from sparse Lagrangian sampling by surface following drifters. We use a polydisperse two-fluid model with large-eddy simulation (LES) resolution and volume-of-fluid surface reconstruction (VOF) to simulate the generation and evolution of turbulence and bubbles beneath short-crested wave breaking events in deep water. Bubble contributions to dissipation and momentum transfer between the water and air phases are considered. Eulerian statistics are obtained from the numerical results, which are available on a fixed grid. Next, we sample the LES/VOF model results with a large number of virtual surface-following drifters that are initially distributed in the numerical domain, regularly or irregularly, before each breaking event. Time-averaged Lagrangian statistics are obtained using the time series sampled by the virtual drifters. We show that convergence of statistics occurs for signals that have minimum length of approximately 1000–3000 wave periods with randomly spaced observations in time and space relative to three-dimensional breaking events. We further show important effects of (i) extent of measurements over depth and (ii) obscuration of velocity measurements due to entrained bubbles, which are the two typical challenges in most of the available in situ observations of upper ocean wave breaking turbulence. An empirical correction factor is developed and applied to the previous observations of Thomson et al. Applying the new correction factor to the observations noticeably improves the inferred energy balance of wind input rates and turbulence dissipation rates. Finally, both our simulation results and the corrected observations suggested that the total wave breaking dissipation rates have a nearly linear relation with active whitecap coverage.

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In The News

UW study finds disturbing climate change evidence in Arctic Ocean

KING5 News, Glenn Farley

A joint study between the University of Washington and University of Alaska has uncovered the presence of 'pancake ice' and tall waves in the Arctic Ocean. Photo: John Guillotte

21 Jan 2020

Warm ocean water delays sea ice for Alaska towns, wildlife

Associated Press, Dan Joling

In the new reality of the U.S. Arctic, open water is the November norm for the Chukchi. Instead of thick, years-old ice, researchers are studying waves and how they may pummel the northern Alaska coastline.

19 Nov 2019

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

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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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