APL-UW Home

Jobs
About
Campus Map
Contact
Privacy
Intranet

Jim Thomson

Senior Principal Oceanographer

Associate 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

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

Stratified Ocean Dynamics of the Arctic — SODA

More Info

31 Oct 2016

Vertical and lateral water properties and density structure with the Arctic Ocean are intimately related to the ocean circulation, and have profound consequences for sea ice growth and retreat as well as for prpagation of acoustic energy at all scales. Our current understanding of the dynamics governing arctic upper ocean stratification and circulation derives largely from a period when extensive ice cover modulated the oceanic response to atmospheric forcing. Recently, however, there has been significant arctic warming, accompanied by changes in the extent, thickness distribution, and properties of the arctic sea ice cover. The need to understand these changes and their impact on arctic stratification and circulation, sea ice evolution, and the acoustic environment motivate this initiative.

Inner Shelf Dynamics

The inner shelf region begins just offshore of the surf zone, where breaking by surface gravity waves dominate, and extends inshore of the mid-shelf, where theoretical Ekman transport is fully realized. Our main goal is to provide provide improved understanding and prediction of this difficult environment. This will involve efforts to assess the influence of the different boundaries — surf zone, mid and outer shelf, air-water interface, and bed — on the flow, mixing and stratification of the inner shelf. We will also gain information and predictive understanding of remotely sensed surface processes and their connection to processes in the underlying water column.

15 Dec 2015

More Projects

Videos

Mapping Underwater Turbulence with Sound

More Info

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

More Videos

Publications

2000-present and while at APL-UW

Tidal current observations through Admiralty Inlet from ferry-mounted current profilers

Guerra, M., J. Thomson, T. Prusa, C. Falkenhayn Maloy, C. Krembs, and B. Sackmann, "Tidal current observations through Admiralty Inlet from ferry-mounted current profilers," J. Ocean Eng. Mar. Energy, EOR, doi:10.1007/s40722-019-00135-w, 2019.

More Info

10 Jun 2019

Admiralty Inlet is a narrow sill located at the northern end of Puget Sound (WA, USA). Circulation through Admiralty Inlet is complex, with tidal currents exceeding 3 m s-1, large variations in fresh water input to the system, and seasonal ocean water intrusions. Long-term observations of the currents across the entire inlet are crucial for understanding circulation through Puget Sound. In this context, the Washington State Department of Transportation (WSDOT) Ferries, which run year round through Admiralty Inlet, provide a cost-effective platform to mount instruments and obtain long time series of currents distributed across the inlet. Through the Ferry-Base Monitoring of Puget Sound Currents project, two down-looking acoustic Doppler current profilers (ADCPs) are installed on board two WSDOT ferries, providing depth profiles of velocities across the inlet since May 2014. All data are quality controlled and organized in an horizontal and vertical grid across the inlet. Data within each grid cell are analyzed to capture tidal current harmonic components. Results agree well with data from fixed bottom-mounted ADCPs, and show large spatial variability in the amplitude of harmonic components, probably related to the bathymetric features of the inlet. Further analysis provides estimates of tidal asymmetry and residual currents through the inlet, which are relevant to water quality within the Puget Sound.

Maximum wave heights from global model reanalysis

Barbariol, F., J.-R. Bidlot, L. Cavaleri, M. Sclavo, J. Thomson, and A. Benetazzo, "Maximum wave heights from global model reanalysis," Prog. Oceanogr., EOR, doi:10.1016/j.pocean.2019.03.009, 2019.

More Info

27 Mar 2019

Very large waves populate the world oceans and challenge seafarers and offshore structures, but their long-term and global assessment is uneasy because of the scarcity of observations and their narrow time-coverage. Modern model reanalysis datasets with high spatio-temporal extent and resolution represent a valuable tool for this scope. In this paper, we use for the first time reanalysis datasets to provide a long-term and global statistical assessment of the maximum wave parameters, namely crest, crest-to-trough and envelope heights. In particular, we rely on the ERA-Interim directional wave spectra that are used to estimate the parameters of the probability distributions of wave maxima. To represent the customary single-point observations we use time extreme statistical models, while to account for the three-dimensional geometry and short-crestedness of stormy ocean waves, the statistical models are extended to space-time. In order to evaluate the accuracy of the reanalysis-based wave maxima estimates we verify them against buoy and stereo-video wave observations gathered in the North Pacific Ocean. We then provide the global assessment of maximum crest, crest-to-trough and envelope heights during typical and extreme conditions, showing the regions attaining the largest values, which we show are located in the mid-latitude storm belts, in particular in the North Atlantic Ocean. With respect to previous wave climate studies that focused on the significant wave height only, in this study we quantify the maximum wave height extent, also highlighting the role of mean wave steepness and kurtosis (measures of nonlinearity) and spectral bandwidth (measure of irregularity). Beside this, we show that the contribution of the short-crestedness is significant and that taking it into account may be relevant for the safety of navigation, ship routing and marine structural design.

A new version of the SWIFT platform for waves, currents, and turbulence in the ocean surface layer

Thomson, J., M. Moulton, A. de Klerk, J. Talbert, M. Guerra, S. Kastner, M. Smith, M. Schwendeman, S. Zippel, and S. Nylund, "A new version of the SWIFT platform for waves, currents, and turbulence in the ocean surface layer," Proc., IEEE/OES 12th Currents, Waves, Turbulence Measurement and Applications Workshop, 10-13 March, San Diego, CA (IEEE, 2019).

More Info

10 Mar 2019

The Surface Wave Instrument Float with Tracking (SWIFT) is a freely drifting platform for measurements of waves, currents, and turbulence in the ocean surface layer. This platform
has been used globally to study wave breaking, wave-current interactions, and waves in ice. A new version (v4) of the buoy has recently been developed and demonstrated in the Office of
Naval Research “Langmuir Circulations” field campaign along the California coast (2017). The new version is built around a 5-beam Acoustic Doppler Current Profiler (Nortek Signature 1000) with a multi-pulse coherent mode for high-resolution turbulence measurements. The new Doppler profiler enables estimates of the turbulent dissipation rate down to 3.5 m below waves, compared with 0.5 m in the previous version, and can measure a much larger range of turbulence levels than the previous version. The new version also uses a broadband Doppler mode to profile the mean currents down to 20 m. Mean Eulerian velocity profiles are estimated from the wave-averaged profiler velocities by applying a wave-following bias correction that scales with the Stokes drift and has twice the vertical decay scale. Finally, the new version supports real-time telemetry of raw sea surface elevations for reconstruction of individual waves by processing a coherent array of multiple SWIFTs, with applications for short-range wave-by-wave forecasting. These combined improvements to the platform are intended to advance understanding of wave processes and applications in the ocean surface layer.

More Publications

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

More News Items

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
Close

 

Close