R/V Lee Thompson entered service in 2022 to support acoustic sensor development. Designed for flat-water, low-speed operations on inland waters, R/V Lee Thompson is a capable, if unusual looking, research platform. Onboard systems render Thompson a semi-autonomous acoustic scanning platform that can target specific positions and run identical courses day after day to test new sonar systems and other acoustic sensors.

APL-UW Team: Jacob Anderson, Scott Bachelor, Amelia Barr, Eric Boget, Ian Borchert, Chanelle Cadot, Chris Craig, Dave Dyer, Ian Good, Diana Haass, Steve Kahle, Jordan Maier, Jestoni Orcejola, Vic Pipinich, Dean Stewart, Ryan Wells, Dylan Wesen

Featured on the cover of the 17 June issue of Science, an international team reports discovery of a subpopulation of polar bears that lives on the southernmost portion of the East Greenland coast. Even though they have access to good sea ice habitat for hunting only a few months each year, they use the mélange of freshwater ice that breaks from glacier fronts as a hunting platform when sea ice disappears from the region each spring.

APL-UW Team: Kristin Laidre, Eric Regehr, Harry Stern
Sponsors: NSF, NASA, Greenland Institute of Natural Resources, Leo Model Foundation, Vetlesen Foundation, Danish Environmental Protection Agency, Danish Ministry of the Environment

Since its launch in 2018, NASA’s ICESat-2 has been collecting precise measurements of elevation spanning the Earth’s surface from pole to pole. Altimeter measurements of snow-covered sea ice in the Arctic show that the annual maximum snow depth and sea ice thickness has decreased by 2 cm and 30 cm, respectively, over this short period.

Team: Ron Kwok and Sahra Kacimi (Jet Propulsion Laboratory)
Sponsor: NASA

Ice Diver melt probes under development at APL-UW are on a mission to find and sample some very old ice several kilometers deep in East Antarctica that preserves climate records from about one million years ago.

Based on a classic melt probe design, the non-recoverable Ice Diver maintains connection to the surface and electrical heating supply through wires spooled inside the vehicle that unwind during its descent into the ice sheet. An optical fiber will be deployed as it descends to measure the depth profile of temperature, which can be used to infer geothermal fluxes within the sheet.

APL-UW Team: Ben Brand, Justin Burnett, Tim Elam, Madison Pickett, Dale Winebrenner
Sponsors: NASA, NSF

Recent reports on the transcutaneous application of sinusoidal tone bursts to fragment kidney stones show that the technique is easily performed by urologists, is minimally invasive, and has few side effects for patients. In one clinical study, where treatment was limited to only 10 minutes, 90% of total stone volume was reduced to less than 2-mm fragments. Lab experiments to maximize breaking stresses in stones suggest that low-frequency ultrasound can initially break large stones into fragments and higher burst wave frequencies can then erode them to dust.

APL-UW Team: Mike Bailey, Bryan Cunitz, Barbrina Dunmire, Mohamed Ghanem, Ga Won (Jenny) Kim, Wayne Kreider, Katy Kuznetsova, John Kucewicz, Adam Maxwell, Katie Ponomarchuk, Shivani Ramesh, Oleg Sapozhnikov, Jeff Thiel, Stephanie Totten, Yak-Nam Wang, Randy Williams
Sponsors: NASA, NIH

One of the tools used by the rover Perseverance to search for signs of ancient microbial life on Mars is PIXL (Planetary Instrument for X-ray Lithochemistry). Based on the instrument's X-ray spectroscopy and other data, the PIXL team reports in Science that a rock in Jezero Crater formed from a slowly cooling, thick magma body deep underground that, due to erosion, is now exposed on the surface. PIXL's elemental chemical and composition map analyses helped scientists determine that this igneous rock was altered by the presence of water that once filled the crater.

APL-UW Team: Tim Elam, Kimberly Sinclair
Sponsor: NASA

Working near the sea ice edge in the Beaufort Sea in fall 2022, researchers used autonomous vehicles, drifters, aerial platforms, and shipboard instruments to measure the dynamics and evolution of near-surface salinity and upper ocean stratification during the transition between summer open water and fall freeze-up. When Arctic sea ice melts it leaves behind a layer of fresh water on the surface that can suppress the upward mixing of warmer, subsurface waters. Can this anomalous sea surface salinity signal be used to predict the timing and spatial pattern of sea ice formation in autumn?

APL-UW Team: Kyla Drushka, Eric D’Asaro, Peter Gaube, Andrey Shcherbina, Mike Steele, Jim Thomson, Alex de Klerk, Justin Burnett, Carlyn Schmidgall, EJ Rainville
Sponsor: NASA

Efforts to miniaturize and simplify infrared radiometer technologies to measure the temperature of the ocean’s surface skin layer have produced a portable, capable instrument that is undergoing a series of sea trials. The radiometer uses a one-point, in situ calibration and corrects emissivity uncertainty with local atmospheric temperature and humidity measurements. It will make practical the collection of ocean skin temperature data from robotic surface vehicles, floats, buoys, and vessels of opportunity. Skin temperature could become a standard measurement for all ocean-going research.

Shelf-slope topography, large riverine inputs, and a strong upwelling season create complex temperature and salinity variations on the Washington coast. Resulting surface and subsurface acoustic ducts affect passive and active sonar operations, especially in the mid-frequency range. Summer 2022 experiments were designed to integrate historical data, observing technologies, and multidisciplinary academic expertise to advance understanding and prediction of hydrographic controls on mid-frequency acoustics in this representative coastal environment.

APL-UW Team: Paul Aguilar, Tara Bergin, Ben Brand, Ramsey Harcourt, Todd Hefner, Katie Kohlman (UW student) Keith Magness, John Mickett, DJ Tang, Peter Tsirushkin (UW student), Guangyu Xu, Jie Yang, Zhihua Zheng (UW student)
Sponsor: ONR

Since 2015, the Seabed Characterization Experiment (SBCEX) has focused on a portion of the continental shelf about 100 km south of Martha’s Vineyard because of its proximity to oceanographic research infrastructure and the region’s extensive patches of thick mud sediments that trap acoustic energy. The overall goal has been to probe the geoacoustic properties of marine mud and examine the effect of sediment layering on acoustic propagation. APL-UW’s unique contribution to SBCEX has been acoustic vector sensing technology and the analytical methods to infer seabed properties from the vector sensor data.

APL-UW Team: Eric Boget, Hanah Choice, Peter Dahl, David Dall'Osto, Alex Soloway
Sponsor: ONR

To generate predictable, reliable power in marine environments with strong tidal currents, researchers have designed a four-bladed cross-flow turbine integrated with a generator and supporting power electronics. Following successful sea trials this year on the test platform R/V Light under heavy loads in the swift currents of Agate Passage, the team is ready to assemble the system into its final configuration: a four-legged bottom lander that can be deployed by a small vessel in coastal locations to power distributed networks and recharge AUVs independent of cabled infrastructure or human intervention.

APL-UW Team: Paul Aguilar, Chris Bassett, Eric Boget, Ben Cunningham, Jesse Dosher, Andy Ellers, James Joslin, Jennie Mowatt, Harlin Wood, Kevin Zack
UW Collaborators: Corey Crisp, Aidan Hunt, Paul Murphy, Brian Polagye, Carl Stringer, Zack Tully
Industry Partners: Bieker Boats, MarineSitu
Sponsor: NAVFAC

With pandemic travel restrictions and logistics challenges now easing, APL-UW oceanographers have resumed their in-person, productive, long-standing research collaborations with Indian and Sri Landan colleagues. Since 2014, ONR has funded a series of research initiatives in the Northern Indian Ocean and Bay of Bengal to more fully understand the ocean’s role in monsoon onset and variability. These efforts have produced an important body of scientific literature and trained a cadre of young scientists focused on the tropical Indian Ocean. Upcoming research cruises on Indian and U.S. vessels will explore the Arabian Sea ‘warm pool’ and its influence on summer monsoon timing and strength.

APL-UW Team: Eric D’Asaro, Michael Ohmart, Dipanjan Chadhuri, Leah Johnson, Michael Kenney, Craig Lee, Luc Rainville, Lou St. Laurent, Harper Simmons
Sponsor: ONR

microSWIFT is a miniaturized, simplified, and inexpensive version of the ocean drifter Surface Wave Instrument Float with Tracking. In fall 2021, microSWIFTs were tossed or launched 10 to 50 at a time into the waves generated by storms offshore the North Carolina barrier islands, and in 2022 dropped from a Navy P-3 aircraft on the forecasted path of Hurricane Ian as it advanced toward the Florida coast. The drifter’s low cost and portability allows deployment of large arrays in extreme ocean conditions, capturing the rich variability of storm-induced ocean waves.

APL-UW Team: Phil Bush, Nate Clemett, Jacob Davis, Alex de Klerk, Morteza Derakhti, Alex Dioso, Emily Iseley, EJ Rainville, Joe Talbert, Jim Thomson
Sponsors: National Oceanographic Partnership Program, U.S. Coastal Research Program

Demonstrated in early 2022 is an integrated system that combines a wave energy converter to harvest and store electricity with an uncrewed undersea vehicle that docks and recharges via a wireless transfer system. Project success relied on the synthesis of serval cutting-edge technologies, collaboration among electrical, mechanical and ocean engineers, as well as partnerships with industry.

Team: Corey Crisp, Jesse Dosher, Alex de Klerk, Paul Gibbs, James Joslin, Emily Iseley, Curtis Rusch, Joe Talbert, Harlin Wood
Sponsor: NAVFAC

Every summer the greatest concentration of APL-UW ocean engineering expertise is focused on the OOI-RCA science and maintenance expedition. In 2022 the 45-day cruise was mobilized across five legs to accommodate crew changes and 60 tons of gear needed to operate, maintain, and enhance the world's largest ocean observatory. Over the course of the calendar year the 200 diverse instruments recovered during the expedition are refurbished and put through a rigorout testing regime in APL-UW facilities to ensure a high operational success rate when they are redeployed to the undersea power and communications network the following summer.

APL-UW Team: Larry Nielson, Eric Strenge, Chris Craig, Dean Stewart, Eric McRae, Dana Manalang, Trina Litchendorf, James Tilley, Able Baca, Grant Dunn, Ian Borchert, Christina Ramirez, Paul Aguilar, Jennie Mowatt, Amy Larsen, Chuck McGuire, Eric Boget, Nick Michel-Hart, Geoff Cram, Kevin Zack, Mike Kenney, Kim Strenge, Justin Schultz, Derek Martin, Ben Brand, Jake Ploskey, Kellen Rosberg, Michael Harding, Tony Enslow, Beau Thomason, Mike Harrington
Sponsor: NSF