BOSTON – The global lens used to follow El Nino has become a bit less accurate after Japan cut by about half the number of buoys in the Western Pacific that monitor changes in the ocean. It will take another four to five offline next year.
Data collected by the anchored buoys include wind measurements, air and water temperatures, currents, and the salinity of the ocean, which are then transmitted to satellites in near real time. The system can look down about 2,500 feet into the Pacific, according to the Japan Agency for Marine-Earth Science and Technology.
The cuts by Japan are “a major issue,” said Kevin Trenberth, a distinguished senior scientist at the National Center of Atmospheric Research in Boulder, Colorado. “There is a task group that has been meeting and planning for how to proceed to monitor the tropical Pacific Ocean.”
The equatorial region is dotted with buoys arranged in rows and stretching from the coast of South America to the waters north of New Guinea. The array, commonly called TAO-Triton, was born in the wake of the strong El Nino of 1982-83 that caught forecasters off guard and triggered floods, droughts and other damage around the world.
Since 2000, the array has been made up of about 70 moorings maintained by the U.S. National Oceanic and Atmospheric Administration and the marine earth-science agency. The task group, which monitors changes in the Pacific that can affect global weather, is part of the Tropical Pacific Observing System. It has representatives from seven nations around the basin, including the U.S. and Japan.
The U.S. maintains most of the buoys at a cost of about $10 million a year, not counting the cost of sending a ship out to visit each one. Japan handled the remaining 15 in the far Western Pacific until the cutbacks that now leave just eight operating. Japan spends about $200,000 per buoy, not counting shipping, said Ken Ando, a researcher at the Japan Agency for Marine-Earth Science and Technology. By 2017, the agency plans to maintain only three or four of the buoys.
“The biggest impact would be the lack of surface wind data,” Ando said.
Winds are an important indicator of the formation of an El Nino. The phenomenon, for reasons not entirely understood, gets going when the trade winds that push sun-warmed waters of the equatorial Pacific into a mound start to weaken. The warm water in the west comes east and an El Nino is born.
A strong El Nino is currently holding sway across the Pacific, bringing drought to Asia and Africa, more typhoons than usual to the Pacific, fewer hurricanes to the Atlantic and a boost in rain to California, though not enough to end the drought there.
In addition to providing valuable data about the Pacific, the buoys help keep satellites calibrated as they watch the world’s weather, said Michael McPhaden, a senior scientist at the National Oceanic and Atmospheric Administration’s Pacific Marine Environmental Laboratory in Seattle. Forecast models used to predict El Nino or La Nina, when the Pacific cools, can be graded with the data, he said.
“This has been a spectacularly successful ocean observing system,” McPhaden said.
Other tools to measure the ocean, such as devices that dive more than a mile before returning to the surface to transmit their data to satellites, “can compensate somewhat,” for the loss of buoys, Trenberth said.
But such devices will be hard-pressed to take the place of the buoys, especially with the chances rising that a La Nina could replace El Nino later this year.