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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

Statistical and dynamical characteristics of extreme wave crests assessed with field measurements from the North Sea

Malila, M.P., F. Barbariol, A. Benetazzo, Ø. Breivik, A.K. Magnusson, J. Thomson, and B. Ward, "Statistical and dynamical characteristics of extreme wave crests assessed with field measurements from the North Sea," J. Phys. Oceanogr., 53, doi:10.1175/JPO-D-22-0125.1, 2022.

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1 Feb 2023

Wave crests of unexpected height and steepness pose a danger to activities at sea, and long-term field measurements provide important clues for understanding the environmental conditions that are conducive to their generation and behavior. We present a novel data set of high-frequency laser altimeter measurements of the sea-surface elevation gathered over a period of 18 years from 2003 to 2020 on an offshore platform in the central North Sea. Our analysis of crest height distributions in the data set shows that mature, high sea states with high spectral steepness and narrow directional spreading exhibit crest height statistics that significantly deviate from standard second order models. Conversely, crest heights in developing sea states with similarly high steepness but wide directional spread correspond well to second order theory adjusted for broad frequency bandwidth. The long-term point time series measurements are complemented with space-time stereo video observations from the same location, collected during five separate storm events during the 2019–2020 winter season. An examination of the crest dynamics of the space-time extreme wave crests in the stereo video data set reveals that the crest speeds exhibit a slowdown localized around the moment of maximum crest elevation, in line with prevailing theory on nonlinear wave group dynamics. Extending on previously published observations focused on breaking crests, our results are consistent for both breaking and non-breaking extreme crests. We show that wave crest steepness estimated from time series using the linear dispersion relation may overestimate the geometrically measured crest steepness by up to 25% if the crest speed slowdown is not taken into account.

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.

Acoustic sensing of ocean mixed layer depth and temperature from uplooking ADCPs

Brenner, S., J. Thomson, L. Rainville, D. Torres, M. Doble, J. Wilkinson, and C. Lee, "Acoustic sensing of ocean mixed layer depth and temperature from uplooking ADCPs," J. Atmos. Ocean. Technol., 40, doi:10.1175/JTECH-D-22-0055.1, 2022.

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1 Jan 2023

Properties of the surface mixed layer (ML) are critical for understanding and predicting atmosphere-sea ice-ocean interactions in the changing Arctic Ocean. Mooring measurements are typically unable to resolve the ML in the Arctic due to the need for instruments to remain below the surface to avoid contact with sea ice and icebergs. Here, we use measurements from a series of three moorings installed for one year in the Beaufort Sea to demonstrate that upward looking Acoustic Doppler Current Profilers (ADCPs) installed on subsurface floats can be used to estimate ML properties. A method is developed for combining measured peaks in acoustic backscatter and inertial shear from the ADCPs to estimate the ML depth. Additionally, we use an inverse sound speed model to infer the summer ML temperature based on offsets in ADCP altimeter distance during open water periods. The ADCP estimates of ML depth and ML temperature compare favourably with measurements made from mooring temperature sensors, satellite SST, and from an autonomous Seaglider. These methods could be applied to other extant mooring records to recover additional information about ML property changes and variability.

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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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