Marine biologists aboard a ship in the Gulf of Mexico are using maps of ocean currents produced with data from the ocean- observing satellite TOPEX/Poseidon to help them locate and count sperm whales and dolphins.
The TOPEX/Poseidon altimeter data, combined with information from the European Space Agency's ERS-2 satellite, are being used in near- real-time to generate circulation feature maps that will be faxed to scientists aboard the research ship R/V Gyre. These maps provide scientists with timely information about rapidly changing ocean features so that scientists can direct the ship toward those areas to determine if whales and dolphins are present.
"There is evidence that whales prefer to feed in the edges of cyclonic eddies, and the satellite data give us a good picture of where those oceanographic features are located," said Dr. George Born, a principal investigator on the TOPEX/Poseidon project from the University of Colorado at Boulder.
The university is generating the ocean maps and sending them directly to the scientists in the Gulf. "The data from TOPEX/Poseidon and ERS-2 greatly enhances our ability to identify and map circulation features as they occur in the Gulf," said Dr. Robert Leben, a co- principal investigator on the project at the University of Colorado at Boulder.
The R/V Gyre left Pascagoula, Mississippi, on October 10 and will survey the northeastern Gulf of Mexico until October 28. A previous survey indicated that whales and dolphins were contacted most frequently in the area where warm water eddies break off from the Gulf Loop Current, a strong ocean current that circulates around the Gulf of Mexico.
"The goal of our cruise is to make a visual and acoustic census of marine mammals and to define their physical and biological habitat in the northeastern Gulf in areas potentially affected by oil and gas activities now or in the future," said Dr. Randall Davis, head of the Marine Biology department at Texas A & M University at Galveston. "Altimeter data like that from TOPEX/Poseidon are the only information that enable on-site adjustments to the cruise plan to optimize the survey track, ultimately saving us time and money."
The TOPEX/Poseidon satellite was developed to study global ocean circulation but it is providing unexpected benefits for marine biologists. "We are very excited that these data are being used in new and different ways. Scientists are continuing to find new applications for this project and are proving they can study not only ocean currents, but also the creatures that inhabit the oceans," said Dr. Lee-Lueng Fu, TOPEX/Poseidon project scientist at NASA's Jet Propulsion Laboratory, Pasadena, CA.
The TOPEX/Poseidon satellite uses an altimeter to bounce radar signals off the ocean's surface to get precise measurements of the distance between the satellite and the sea surface. These data are combined with measurements from other instruments that pinpoint the satellite's exact location in space. Every 10 days, scientists are able to produce a complete map of global ocean topography, the barely perceptible hills and valleys found on the sea surface. With detailed knowledge of ocean topography, scientist can then calculate the speed and direction of worldwide ocean currents.
The R/V Gyre expedition is sponsored by Texas A & M University, the Texas Institute of Oceanography and the National Biological Service.
TOPEX/Poseidon is a joint mission of NASA and the French space agency, the Centre National d'Etudes Spatiales (CNES). The Jet Propulsion Laboratory manages the U.S. portion of the mission for NASA's Office of Mission to Planet Earth, Washington, DC. The Mission to Planet Earth is a long-term, coordinated research effort to study the Earth as a global environmental system.
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