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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

Rapid deterministic wave prediction using a sparse array of buoys

Fisher, A., J. Thomson, and M. Schwendeman, "Rapid deterministic wave prediction using a sparse array of buoys," Ocean Eng., 228, doi:10.1016/j.oceaneng.2021.108871, 2021.

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15 May 2021

A long-standing problem in maritime operations and ocean development projects has been the prediction of instantaneous wave energy. Wave measurements collected using an array of freely drifting arrays of Surface Wave Instrument Float with Tracking (SWIFT) buoys are used to test methods for phase-resolved wave prediction in a wide range of observed sea states. Using a linear inverse model in directionally-rich, broadbanded wave fields can improve instantaneous heave predictions by an average of 63% relative to statistical forecasts based on wave spectra. Numerical simulations of a Gaussian sea, seeded with synthetic buoys, were used to supplement observations and characterize the spatiotemporal extent of reconstruction accuracy. Observations and numerical results agree well with theoretical deterministic prediction zones proposed in previous studies and suggest that the phase-resolved forecast horizon is between 1–3 average wave periods for a maximum measurement interval of 10 wave periods for ocean wave fields observed during the experiment. Prediction accuracy is dependent on the geometry and duration of the measurements and is discussed in the context of the nonlinearity and bandwidth of incident wave fields.

Comparing observations and parameterizations of ice–ocean drag through an annual cycle across the Beaufort Sea

Brenner, S., L. Rainville, J. Thomson, S. Cole, C. Lee, "Comparing observations and parameterizations of ice–ocean drag through an annual cycle across the Beaufort Sea," J. Geophys. Res., EOR, doi:10.1029/2020JC016977, 2021.

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29 Mar 2021

Understanding and predicting sea ice dynamics and ice‐ocean feedback processes requires accurate descriptions of momentum fluxes across the ice‐ocean interface. In this study, we present observations from an array of moorings in the Beaufort Sea. Using a force‐balance approach, we determine ice‐ocean drag coefficient values over an annual cycle and a range of ice conditions. Statistics from high resolution ice draft measurements are used to calculate expected drag coefficient values from morphology‐based parameterization schemes. With both approaches, drag coefficient values ranged from approximately 1–10 x 10-3, with a minimum in fall and a maximum at the end of spring, consistent with previous observations. The parameterizations do a reasonable job of predicting the observed drag values if the under ice geometry is known, and reveal that keel drag is the primary contributor to the total ice‐ocean drag coefficient. When translations of bulk model outputs to ice geometry are included in the parameterizations, they overpredict drag on floe edges, leading to the inverted seasonal cycle seen in prior models. Using these results to investigate the efficiency of total momentum flux across the atmosphere‐ice‐ocean interface suggests an inter‐annual trend of increasing coupling between the atmosphere and the ocean.

Long-term observations of the group structure of surface waves in ice

Gemmrich, J., T. Mudge, and J. Thomson, "Long-term observations of the group structure of surface waves in ice," Ocean Dyn., 71, 343-356, doi:10.1007/s10236-020-01424-x, 2021.

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1 Mar 2021

Several years of surface wave observations in the Chukchi Sea reveal wave groups are a common feature in open water and ice-covered conditions. The strength of the groupiness, here characterized by the group factor, is well correlated with the characteristic wave steepness, the spectral bandwidth, and the Benjamin-Feir Index. The general finding is enhanced groupiness in ice. However, the trends with wave characteristics are opposite from ice to open water, and suggest different mechanisms. In ice, groupiness increases with decreasing steepness, increasing bandwidth, and decreasing Benjamin-Feir Index. In open water, the trends indicate that both linear superposition of phase-coherent waves and nonlinear behaviour are important for the generation of wave groups. We hypothesize that in ice-covered conditions, directional spreading reduces the effective bandwidth in the dominant wave direction, possibly due to modified four-wave nonlinear transfer spreading high-frequency energy to lateral directions. This reduced effective bandwidth is then conducive to enhanced group formation by linear superposition. However, an increased high-frequency noise floor of the in-ice observations would also be consistent with the observed increase in omni-directional bandwidth. Without directional measurements, neither of these two processes can be favoured with certainty.

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In The News

Coast Guard icebreaker Polar Star departs Seattle for important arctic mission

KING 5 News (Seattle), Glenn Farley

The Seattle-based Polar Star has several important duties in the Arctic, including sending a strong message to Russia and conducting unique research.

4 Dec 2020

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

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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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