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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

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., EOR, doi:10.1007/s10236-019-01301-2, 2019.

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6 Sep 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.

Impact of swell on the wind-sea and resulting modulation of stress

Vincent, C.L., J. Thomson, H.C. Graber, and C.O. Collins III, "Impact of swell on the wind-sea and resulting modulation of stress," Prog. Oceanogr., EOR, doi:10.1016/j.pocean.2019.102164, 2019.

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19 Aug 2019

Highlights

• The presence of swell in the sea state is shown to modulate the energy in the wind sea spectral tail.

• The f-4 and f-5 power laws used to describe the tail of the wind sea spectrum when swell is not present, are extended to the spectra including swell. This requires including swell steepness in the formulation of the power law coefficients and into the equation for the transition frequency between the Equilibrium and Saturation ranges.

• The spectra of large swell with very low winds also display f-4 and f-5 power laws. The power law coefficients however are a function of swell steepness, not wind speed.

• Direction of the waves in the high frequency range of the spectrum is that of the wind, no matter the swell size, steepness or direction.

• The reformulation of the equations for the spectral tail to include swell allows development of a simple equation for stress encompassing the swell effect.

Constraining Southern Ocean air–sea–ice fluxes through enhanced observations

Swart, S., and 19 others including J. Thomson and J. Girton, "Constraining Southern Ocean air–sea–ice fluxes through enhanced observations," Front. Mar. Sci., 6, 421, doi:10.3389/fmars.2019.00421, 2019.

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31 Jul 2019

Air–sea and air–sea–ice fluxes in the Southern Ocean play a critical role in global climate through their impact on the overturning circulation and oceanic heat and carbon uptake. The challenging conditions in the Southern Ocean have led to sparse spatial and temporal coverage of observations. This has led to a 'knowledge gap' that increases uncertainty in atmosphere and ocean dynamics and boundary-layer thermodynamic processes, impeding improvements in weather and climate models. Improvements will require both process-based research to understand the mechanisms governing air-sea exchange and a significant expansion of the observing system. This will improve flux parameterizations and reduce uncertainty associated with bulk formulae and satellite observations. Improved estimates spanning the full Southern Ocean will need to take advantage of ships, surface moorings, and the growing capabilities of autonomous platforms with robust and miniaturized sensors. A key challenge is to identify observing system sampling requirements. This requires models, Observing System Simulation Experiments (OSSEs), and assessments of the specific spatial-temporal accuracy and resolution required for priority science and assessment of observational uncertainties of the mean state and direct flux measurements. Year-round, high-quality, quasi-continuous in situ flux measurements and observations of extreme events are needed to validate, improve and characterize uncertainties in blended reanalysis products and satellite data as well as to improve parameterizations. Building a robust observing system will require community consensus on observational methodologies, observational priorities, and effective strategies for data management and discovery.

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In The News

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

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

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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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