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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

Persistent Measurements of Surface Waves in Landfast Ice Using Fiber Optic Telecommunication Cables

The high-resolution data collected during this research will help address fundamental questions about wave attenuation in landfast ice and breakup. The research is motivated by two questions: (1) What is the spatial and temporal variability of wave attenuation in landfast sea ice? (2) What drives landfast breakup? (Collaborative research with M. Smith, WHOI)

30 Aug 2023

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.

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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

Statistics of bubble plumes generated by breaking surface waves

Derakhti, M., J. Thomson, C. Bassett, M. Malila, and J.T. Kirby, "Statistics of bubble plumes generated by breaking surface waves," J. Geophys. Res., 129, doi:10.1029/2023JC019753, 2024.

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17 May 2024

We examine the dependence of the penetration depth and fractional surface area (e.g., whitecap coverage) of bubble plumes generated by breaking surface waves on various wind and wave parameters over a wide range of sea state conditions in the North Pacific Ocean, including storms with sustained winds up to 22 m s-1 and significant wave heights up to 10 m. Our observations include arrays of freely drifting SWIFT buoys together with shipboard systems, which enabled concurrent high-resolution measurements of wind, waves, bubble plumes, and turbulence. We estimate bubble plume penetration depth from echograms extending to depths of more than 30 m in a surface-following reference frame collected by downward-looking echosounders integrated onboard the buoys. Our observations indicate that mean and maximum bubble plume penetration depths exceed 10 and 30 m beneath the surface during high winds, respectively, with plume residence times of many wave periods. They also establish strong correlations between bubble plume depths and wind speeds, spectral wave steepness, and whitecap coverage. Interestingly, we observe a robust linear correlation between plume depths, when scaled by the total significant wave height, and the inverse of wave age. However, scaled plume depths exhibit non-monotonic variations with increasing wind speeds. Additionally, we explore the dependencies of the combined observations on various non-dimensional predictors used for whitecap coverage estimation. This study provides the first field evidence of a direct relation between bubble plume penetration depth and whitecap coverage, suggesting that the volume of bubble plumes could be estimated by remote sensing.

Measuring turbulence from wave-following platforms

Zeiden, K., and J. Thomson, "Measuring turbulence from wave-following platforms," In Proc., IEEE/OES 13th Current, Waves and Turbulence Measurement (CWTM), 18-20 March 2024, Wanchese, NC, doi:10.1109/CWTM61020.2024.10526345 (IEEE, 2024).

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15 May 2024

Autonomous surface platforms equipped with pulse-coherent high-resolution (HR) ADCPs are a promising tool for measuring turbulence and estimating turbulent dissipation rates, ε(z), close to the air-sea interface. However, surface gravity waves generate significant bias in ε(z) if not sufficiently separated from the turbulent signal. In a previous study, the authors developed a method of isolating wave orbital velocities from the data using empirical orthogonal functions (EOFs). Low-mode EOFs had characteristics of surface gravity waves, while higher-mode EOFs had characteristics of turbulence. After filtering empirical wave profiles constructed from the low-mode EOFs from the data, resultant ε(z) were in close agreement with law-of-the-wall scaling during quiescent conditions. In this study, we further validate the EOF-filtering technique by comparing EOFs of the HR ADCP data with those computed from synthetic wave data which does not contain turbulence. As expected, low-mode EOFs of the synthetic data are in strong agreement with those of the real data, while high-mode EOFs reflect only noise due to the absence of turbulence. Wave profiles constructed from the low-mode EOFs are then used to quantify the potential for bias in ε(z) if wave velocities are not sufficiently filtered from the data.

Multiscale measurements of hurricane waves using buoys and airborne radar

Davis, J.R., J. Thomson, B.J. Butterworth, I.A. Houghton, C. Fairall, E.J. Thompson, and G. de Boer, "Multiscale measurements of hurricane waves using buoys and airborne radar," In Proc., IEEE/OES 13th Current, Waves and Turbulence Measurement (CWTM), 18-20 March 2024, Wanchese, NC, doi:10.1109/CWTM61020.2024.10526332 (IEEE, 2024).

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15 May 2024

The processes important to hurricane wave generation cover scales from kilometers to centimeters. Within a storm, waves have complex spatial variations that are sensitive to hurricane size, strength and speed. This makes it challenging to measure the spatial variability of hurricane waves with any single instrument. To obtain both broad spatial coverage and resolve the full range of wave scales, we combine arrays of drifting wave buoys with airborne radar altimetry. The microSWIFT (UW-APL) and Spotter (Sofar) buoys are air-deployed along a given storm track. These buoys resolve the scalar wave frequency spectrum from 0.05 Hz to 0.5 Hz, which is approximately 600 m to 6 m wavelength (in deep water). The Wide Swath Radar Altimeter (WSRA) flies into hurricanes aboard the NOAA Hurricane Hunter P-3 aircraft. The radar altimetry data is processed to produce a 2D directional spectrum from 2.5 km to 80 m wavelength, and the radar backscatter provides an estimate of the mean square slope down to centimeter wavelengths. We introduce a method to use colocated mean square slope observations from each instrument to infer the shape of the spectral tail from 0.5 Hz to almost 3 Hz. The method is able to recover the frequency f–5 tail characteristic of the saturation range expected at these frequencies (based on theory and measurements in lower wind speeds). We also explore the differences between WSRA and buoy mean square slopes, which represent the mean square slope of the intermediate wavelength waves (6 m down to 20 cm). Together, the fusion of these wave measurements provides a multiscale view of the hurricane-generated waves. These ocean surface waves are critical as drivers of the air-sea coupling that controls storm evolution and as drivers of coastal impacts by hurricanes.

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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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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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