Run Silent, Run Deep

OSU's growing fleet of underwater gliders monitors the Pacific Ocean

This map of the Endurance Array off the Northwest coast shows mooring sites planned at water depths of 25, 80 and 500 meters in two lines — one off Newport, Oregon, and the other off Gray's Harbor, Washington. Gliders will provide additional cross-shelf sampling. (Map courtesy of the Ocean Observatories Initiative's implementing organizations)

For more than half a century, oceanographers have ventured out of Newport to measure, probe and monitor the Pacific Ocean off the central Oregon Coast. And since the 1950s, these seafaring researchers have recorded about 4,000 “profiles” of the near-shore waters — surface to bottom measurements of temperature, salinity and oxygen levels that begin to tell us how the world’s largest ocean influences everything from our weather to fisheries.

Then in 2005, Oregon State University scientists tested a prototype undersea glider that could be programmed to patrol beneath the ocean surface and collect many of the same measurements. At the time, the scientists predicted that these gliders could revolutionize the study of the world’s oceans.

Their vision is rapidly becoming a reality.

In the past five years, a fleet of gliders operated by OSU’s College of Oceanic and Atmospheric Sciences has covered more than 43,000 kilometers, a distance that would more than circumnavigate the globe. Even more striking is the productivity of the sleek, torpedo-like machines. In those five years, the gliders have recorded more than 156,000 oceanic profiles, almost 40 times what six decades of shipboard studies have provided.

“That’s pretty amazing, when you think about it,” says Jack Barth, a professor of oceanography and one of OSU’s glider pioneers. “Each year alone, we log more profiles than have ever been recorded via ship off Newport. And the beauty of gliders is that the data is continual. They record 24 hours a day, regardless of the weather or how rough the sea is.”

Underwater vehicles are not new to research, but the autonomous gliders used by OSU differ from earlier versions because they lack tethers or propellers — meaning they don’t have to be accompanied by a ship. The gliders instead are driven by buoyancy changes, which lessen the overall energy consumption. By displacing seawater, the gliders increase their volume and become more buoyant. Or they can decrease their volume and become heavier, sinking lower in the water. Small wings on the gliders translate some of that vertical motion into forward motion.

The machines can be programmed to run for three to five weeks, from near-shore to the continental slope, and every six hours they rise to the surface and transmit data to OSU computers via satellite. The data they collect informs scientists on conditions including El Niño and La Niña, hypoxia (low oxygen) and resulting “dead zones” and harmful algal blooms.

Expanding the Fleet

Barth and fellow OSU oceanographer Kipp Shearman, together with their team of faculty research assistants and graduate students, operate a fleet of nine gliders. Six are Slocum gliders, manufactured by Teledyne Webb Research of Falmouth, Massachusetts, and based on the original prototype tested in 2005. Three are new Seagliders developed at the University of Washington. The Slocums can go as deep as 200 meters below the surface; the newer Seagliders can explore the ocean down to 1,000 meters and stay out for months.

Each glider costs between $100,000 and $200,000, so the OSU fleet is an impressive resource that is about to get much better.

Three years ago, OSU was selected as one of the lead institutions for the $387 million Ocean Observatories Initiative, a National Science Foundation-funded project to study the world’s oceans and their relationship to climate variability. One component of that project is to create a coastal observatory off the Northwest coast that will use moorings, buoys and gliders to better observe and monitor the ocean.

While engineers are still designing the hardware and instrumentation for the moorings, OSU in 2012 will deploy six new gliders — plus an additional half-dozen gliders on shore to be rotated into the observation array — bringing the total fleet to 21. And the new gliders will include instrumentation that has piqued the interest of ecologists, the fishing industry and others.

“In addition to the core instrumentation, these new gliders will be able to use acoustics to measure water velocity,” Barth adds. “For the first time, we will be able to nearly simultaneously map ocean currents – from the surface to the bottom of the ocean – and detect just where these underwater ‘rivers’ run.”

Public Access to Data

Data from the Ocean Observatories Initiative will be available as they are being collected and shared with researchers and the public alike.

“The fishermen we’ve talked to are intensely interested in the data we will generate,” he says. “Crabbers don’t want to put their pots into areas that have strong bottom currents, nor do trawlers want to contend with strong drifts. The findings will also be important for ecologists studying larval dispersal of marine animals.”

Technology is advancing so rapidly, Barth says, that the gliders will carry new instruments as early as the next year or two. “We’re putting hydrophones onto the moorings, for example, and there’s no reason why we can’t put them onto the gliders and listen for marine mammals or fish that have been tagged with transmitters.”

OSU’s fleet of 21 gliders will enable Barth, Shearman, scientific colleagues and the public to continually monitor five east-west transects — off the northwest tip of Washington, Gray’s Harbor, Cape Mears, Newport, and Coos Bay — while rotating the machines for calibration, maintenance and battery charging. The newest gliders will allow them to run a north-south pattern about 150 kilometers off the coast and, with separate NOAA funding, begin a new east-west transect off Crescent City, California.

“We’ve been doing the Newport sector for five years now,” Barth says, “and we’ve seen things we’ve never seen before, from the influence of coastal rivers, to details about hypoxia. It’s become one of the most well-studied ocean regions on Earth. Now we’ll be able to get similar coverage up and down the coast, from the California border to Vancouver Island.

“It will be,” he added, “revolutionary.”

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See a March 23, 2011 story about deployment of new Ocean Observatories Initiative buoys off Newport, Ore. and Grays Harbor, Wash.

For information about supporting research and teaching through faculty endowments, contact the Oregon State University Foundation, 1-800-354-7281 or visit CampaignforOSU.org.

One Response to “Run Silent, Run Deep”

  1. Raven Dorr says:

    The data and imaging gathered by the OSU/COAS Glider Research Group would be extremely helpful for the research I’m conducting as an undergraduate at Oregon State University. Can you suggest how I may obtain these images and data?

    Thanks,

    Raven Dorr
    (541)609-8925
    dorrr@onid.orst.edu