DURHAM, N.H. A technology commonly used to map the bottom of the deep ocean can also detect gas seeps in the water column with remarkably high fidelity, according to scientists from the University of New Hampshire and the National Oceanic and Atmospheric Administration (NOAA). This finding, made onboard the NOAA ship Okeanos Explorer in the Gulf of Mexico, will lead to more effective mapping of these gas seeps and, ultimately, enhanced understanding of our ocean environments.
The mapping technology, multibeam sonar, is an echo-sounding technology that surveys a wide, fan-shaped swath of the seafloor, providing much greater coverage than the single-beam sonar systems previously used to map seeps. "We wanted to see whether we could map a large area of gaseous seeps effectively using this technology, and how well the multibeam sonar compared to our very sensitive single-beam sonars," says Tom Weber of UNH's Center for Coastal Mapping, who was lead scientist of this mission. "It turns out it works wonderfully." The multibeam sonar on the Okeanos Explorer produced data to make high-resolution maps of gas in the water column in depths ranging from 3,000 to 7,000 feet.
Working jointly with scientists and technicians from NOAA's Office of Ocean Exploration and Research (OER) and the Bureau of Ocean Energy Management (BOEM), Weber and colleagues mapped more than 17,000 square kilometers of the Gulf of Mexico from Aug. 22 through Sept. 10, 2011.
Sonar finds features on the ocean floor much the way a bat tracks its dinner: "It's an acoustic wave hitting the target and reflecting back," says Weber. Multibeam sonar sends those sound waves in many directions at the same time, enabling it to "see" a swath of targets that is much wider than what would be observed with a single-beam sonar. While it's known to be an effective tool for mapping large, stable items like the bottom of the ocean, it wasn't designed to detect targets within the water c
|Contact: Beth Potier|
University of New Hampshire