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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

Hurricane Coastal Impacts

APL-UW scientists are collaborating with 10 research teams to tackle the National Oceanographic Partnership Program (NOPP) project goals: to enable better understanding and predictive ability of hurricane impacts, to serve and protect coastal communities. The APL-UW team will contribute air-deployed buoys to provide real time observations of hurricane waves and wave forcing that can be ingested by modeling groups, improving forecasts and validating hindcasts.

14 Dec 2021

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

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Videos

microSWIFTs: Tiny Oceanographic Floats Measure Extreme Coastal Conditions

These small, inexpensive ocean drifters are the latest generation of the Surface Wave Instrument Float with Tracking (SWIFT) platform developed at APL-UW. They are being used in several collaborative research experiments to increase the density of nearshore wave observations.

19 Apr 2022

Using a Wave Energy Converter for UUV Recharge

This project demonstrates the interface required to operate, dock, and wirelessly charge an uncrewed underwater vehicle with a wave energy converter.

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11 Apr 2022

Uncrewed underwater vehicles (UUVs) predominantly use onboard batteries for energy, limiting mission duration based on the amount of stored energy that can be carried by the vehicle. Vehicle recharge requires recovery using costly, human-supported vessel operations. The ocean is full of untapped energy in the form of waves that, when converted to electrical energy by a wave energy converter (WEC), can be used locally to recharge UUVs without human intervention. In this project we designed and developed a coupled WEC-UUV system, with emphasis on the systems developed to interface the UUV to the WEC.

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.

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Publications

2000-present and while at APL-UW

Experimental validation of float array tidal current measurements in Agate Pass, WA

Harrison, T.W., N. Clemett, B. Polagye, and J. Thomson, "Experimental validation of float array tidal current measurements in Agate Pass, WA," J. Atmos. Ocean. Technol., EOR, doi:10.1175/JTECH-D-22-0034.1, 2023.

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12 Jan 2023

Tidal currents, particularly in narrow channels, can be challenging to characterize due to high current speeds (> 1 m s-1), strong spatial gradients, and relatively short synoptic windows. To assess tidal currents in Agate Pass, WA, we cross-evaluated data products from an array of acoustically-tracked underwater floats and from acoustic Doppler current profilers (ADCPs) in both station-keeping and drifting modes. While increasingly used in basin-scale science, underwater floats have seen limited use in coastal environments. This study presents the first application of a float array towards small-scale (< 1 km), high resolution (< 5 m) measurements of mean currents in energetic tidal channel and utilizes a new prototype float, the μFloat, designed specifically for sampling in dynamic coastal waters. We show that a float array (20 floats) can provide data with similar quality to ADCPs, with measurements of horizontal velocity differing by less than 10% of nominal velocity, except during periods of low flow (0.1 m s-1). Additionally, floats provided measurements of the three dimensional temperature field, demonstrating their unique ability to simultaneously resolve in situ properties that cannot be remotely observed.

Observations of river plume mixing in the surf zone

Kastner, S.E., A.R. Horner-Devine, J.M. Thomson, and S.N. Giddings, "Observations of river plume mixing in the surf zone," J. Phys. Oceanogr., EOR, doi:10.1175/JPO-D-21-0286.1, 2022.

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16 Dec 2022

We use salinity observations from drifters and moorings at the Quinault River mouth to investigate mixing and stratification in a surf-zone trapped river plume. We quantify mixing based on the rate of change of salinity, DS/Dt, in the drifters' quasi-Lagrangian reference frame. We estimate a constant value of the vertical eddy diffusivity of salt of Kz = 2.2±0.6×10-3 m2 s-1, based on the relationship between vertically integrated DS/Dt and stratification, with values as high as 1x10-2m2 s-1 when stratification is low. Mixing, quantified as DS/Dt, is directly correlated to surf-zone stratification, and is therefore modulated by changes in stratification caused by tidal variability in freshwater volume flux. High DS/Dt is observed when the near-surface stratification is high and salinity gradients are collocated with wave-breaking turbulence. We observe a transition from low stratification and low DS/Dt at low tidal stage to high stratification and high DS/Dt at high tidal stage. Observed wave-breaking turbulence does not change significantly with stratification, tidal stage or offshore wave height; as a result we observe no relationship between plume mixing and offshore wave height for the range of conditions sampled. Thus, plume mixing in the surf zone is altered by changes in stratification; these are due to tidal variability in freshwater flux from the river and not wave conditions, presumably because depth-limited wave breaking causes sufficient turbulence for mixing to occur during all observed conditions.

Air-ice-ocean interactions and the delay of autumn freeze-up in the Western Arctic Ocean

Thomson, J., M. Smith, K. Drushka, and C. Lee, "Air-ice-ocean interactions and the delay of autumn freeze-up in the Western Arctic Ocean," Oceanography, 35, 76-87, doi:10.5670/oceanog.2022.124, 2022.

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1 Dec 2022

Arctic sea ice is becoming a more seasonal phenomenon as a direct result of global warming. Across the Arctic, the refreezing of the ocean surface each autumn now occurs a full month later than it did just 40 years ago. In the western Arctic (Canada Basin), the delay is related to an increase in the seasonal heat stored in surface waters; cooling to the freezing point requires more heat loss to the atmosphere in autumn. In the marginal ice zone, the cooling and freezing process is mediated by ocean mixing and by the presence of remnant sea ice, which may precondition the ocean surface for refreezing. The delay in refreezing has many impacts, including increased open ocean exposure to autumn storms, additional wave energy incident to Arctic coasts, shifts in animal migration patterns, and extension of the time window for transit by commercial ships along the Northern Sea Route. This article reviews the observed trends in the western Arctic and the processes responsible for these trends, and provides brief in situ observations from the Beaufort Sea that illustrate some of these processes.

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In The News

UW-developed wave sensors deployed to improve hurricane forecasts

UW News

Jacob Davis, a UW doctoral student in civil and environmental engineering, and members of the U.S. Navy’s VXS-1 Squadron deployed wave sensing buoys in the path of Hurricane Ian, before the hurricane made landfall.

28 Sep 2022

See delicate rib vortices encircle breaking ocean waves

Scientific American, Joanna Thompson

These little-studied mini twisters form beautiful loops under the water’s surface. Until the past decade or so few people in the scientific community paid much attention to rib vortices, partly because they are difficult to photograph. The ephemeral twists require a high-resolution camera and precise timing to capture.

1 Aug 2022

U.S. icebreaker gap with Russia a growing concern as Arctic 'cold war' heats up

Washington Times, Mike Glenn

Warming trends have spurred a chase for trade routes, natural resources at top of the world. Vessels like the Healy and the Polar Star are the most effective tools for maintaining access to the icy regions for scientific, economic and security purposes, advocates say.

23 Sep 2021

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