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Alex de Klerk

Field Engineer II






B.S. Materials Science and Engineering, University of Washington, 2010


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

Turbulence Generated by Tides in the Canal de Chacao, Chile

At a proposed tidal energy conversion site in southern Chile, APL-UW researchers are measuring the magnitude and scales of turbulence, both to aid in the design of turbines for the site and to understand the fundamental dynamics of flows through the channel.

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7 Mar 2013

Principal Investigator Jim Thomson chronicled all phases of the Chilean experiment through posts to the New York Times 'Scientist at Work' blog.

Storm Chasing in the North Pacific

A research cruise was conducted in October 2012 to find stormy conditions and heavy seas far out in the Pacific Ocean. The objectives were to measure, with remote sensing technologies, the intense winds, large waves, and the turbulence generated by wave breaking. Understanding the balance of energy going into and breaking out of waves will be used to improve open ocean wave forecasts.

2 Nov 2012

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2000-present and while at APL-UW

Biofouling effects on the response of a wave measurement buoy in deep water

Thomson, J., J. Talbert, A. de Klerk, A. Brown, M. Schwendeman, J. Goldsmith, J. Thomas, C. Olfe, G. Cameron, and C. Meinig, "Biofouling effects on the response of a wave measurement buoy in deep water," J. Atmos. Ocean. Technol., 32, 1281-1286, doi:10.1175/JTECH-D-15-0029.1, 2015.

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1 Jun 2015

The effects of biofouling on a wave measurement buoy are examined using concurrent data collected with two Datawell Waveriders at Ocean Station P: one heavily biofouled at the end of a 26-month deployment, the other newly deployed and clean. The effects are limited to the high-frequency response of the buoy and are correctly diagnosed with the spectral "check factors" that compare horizontal and vertical displacements. A simple prediction for the progressive change in frequency response during biofouling reproduces the check factors over time. The bulk statistical parameters of significant wave height, peak period, average period, and peak direction are only slightly affected by the biofouling because the contaminated frequencies have very low energy throughout the comparison dataset.

Turbulence measurements from moving platforms

Thomson, J., J. Talbert, A. de Klerk, S. Zippel, M. Guerra, and L. Kilcher, "Turbulence measurements from moving platforms," Proc. 11th IEEE/OES Current, Waves and Turbulence Measurement (CWTM) Workshop, 2-6 March, St. Petersburg, FL, doi:10.1109/CWTM.2015.7098107 (IEEE, 2015).

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2 Mar 2015

Two recent methods for making high-fidelity turbulence measurements from moving platforms are described and demonstrated. The first is a method for measuring profiles of near-surface turbulence from a wave-following 'SWIFT' buoy. The second is a method for measuring time series of turbulence from a submerged compliant mooring. Both approaches use coherent Doppler instruments and inertial motion units (IMUs). In the buoy method, wave motions (e.g., pitch, roll, and heave) are quantified via GPS and IMU measurements. These wave motions are not present in the turbulence observations, because buoy follows the wave orbital motion, and thus the turbulent velocities are processed in the wave-following reference frame. In the mooring method, IMU measurements track the mooring motions (e.g., strum and kiting) and these motions are removed in post-processing to obtain turbulent velocities in the fixed earth reference frame. These approaches successfully quantify turbulence in regions previously unavailable or limited by the noise and spatial aliasing of sampling from bottom-mounted platforms.

Low-cost ultility-scale wave energy enabled by magnetostriction

Nair, B., R. Shendure, J. Nachlas, A. Gill, Z. Murphree, J. Campbell, V. Challa, J. Thomson, J. Talbert, A. De Klerk, and C. Rusch, "Low-cost ultility-scale wave energy enabled by magnetostriction," Proc., 1st Marine Energy Technology Symposium, METS13, 10-11 April, Washington, D.C., 2013.

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10 Apr 2013

Oscilla Power, Inc. (OPI) is developing a patented magnetostrictive wave energy harvester (MWEH) that could enable the disruptively low-cost production of grid-scale electricity from ocean waves, a large-scale resource that is more predictable and more proximal to demand growth than solar or wind. Designed to operate cost-effectively across a wide range of wave conditions, the MWEH will be the first use of reverse magnetostriction for large-scale energy production.

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Tidal turbulence spectra from a compliant mooring

Thomson, J., L. Kilcher, M. Richmond, J. Talbert, A. deKlerk, B. Polagye, M. Guerra, and R. Cienfuegos, "Tidal turbulence spectra from a compliant mooring," Proc., 1st Marine Energy Technology Symposium, METS2013, 10-11 April, Washington, D.C., 2013.

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10 Apr 2013

A compliant mooring to collect high frequency turbulence data at a tidal energy site is evaluated in a series of short demonstration deployments. The Tidal Turbulence Mooring (TTM) improves upon recent bottom-mounted approaches by suspending Acoustic Doppler Velocimeters (ADVs) at mid-water depths (which are more relevant to tidal turbines). The ADV turbulence data are superior to Acoustic Doppler Current Profiler (ADCP) data, but are subject to motion contamination when suspended on a mooring in strong currents. In this demonstration, passive stabilization is shown to be sufficient for acquiring bulk statistics of the turbulence, without motion correction. With motion correction (post-processing), data quality is further improved. Results from two field sites are compared, and the differences are attributed to the generation of large eddies by headlands and sills.


SWIFT: Surface Wave Instrument Float with Tracking

Record of Invention Number: 46566

Jim Thomson, Alex De Klerk, Joe Talbert


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


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