El Niño, characterized by warmer sea-surface water in the equatorial Eastern Pacific, is often associated with greater rainfall on much of the U.S. West Coast and frequently enhances the encroachment of storm surges by raising regional sea level for several months at a time. The opposite phenomenon is known as La Niña.
An autonomous underwater glider known as Spray monitors water temperature and other parameters off Dana Point, Calif. Scripps physical oceanographer Dan Rudnick said the Spray data so far strongly agree with a measure of National Oceanographic and Atmospheric Administration (NOAA)-based El Niño findings based on temperature data collected at the equator. Currently, NOAA forecasts a probability of El Niño conditions at 70 percent during the Northern Hemisphere summer and reaching 80 percent during the fall and winter.
The Spray data are one of several means by which scientists are following the developing El Niño. Deployment of Spray gliders off the Galapagos Islands began in October 2013 in a joint project with Woods Hole Oceanographic Institution and the Oceanographic Institution of the Ecuadorian Navy. The National Science Foundation (NSF) and NOAA fund this project, called Repeat Observations by Gliders in the Equatorial Region.
The next Spray deployment in the Galapagos is scheduled for July.
Scripps oceanographers have beefed up their data coverage in the equatorial Pacific Ocean as part of a larger endeavor to demonstrate how long-term observations in the tropical Pacific Ocean can be improved. Dean Roemmich, a Scripps oceanographer, said that a series of floating devices have provided an unprecedented view of the Pacific-wide evolution of El Niño conditions. A burst of westerly wind in the western Pacific in January resulted in a strong subsurface pulse of energy that crossed the equatorial Pacific from February to April.
“This warm temperature anomaly became shallower in the eastern Pacific where it was felt as a warming of sea surface temperature,” Roemmich said. “The next few months will tell whether this warm pulse is followed by others and whether it will develop into an El Niño.”