Off the southern coast of Africa, where the Indian and Atlantic oceans meet, high-tech sensors on buoys moored in a long line await subtle changes in temperature that could affect climate all the way to Europe.
The purpose of the buoy line, stretching more than 600 miles across the sea, is to help researchers determine how the flow of warm, salty water from the Indian Ocean affects the cooler, less salty Atlantic Ocean. The exchange influences rainfall and climate, but little is known about the cycle of currents that push heat from one ocean to the next.
“We do know the Atlantic would be colder without it, so we have lots of evidence the system fluctuates,” said Deirdre Byrne, a visiting professor at the University of Cape Town in South Africa.
“But as a practical matter, how do you measure something that happens in a fairly remote area? We know almost nothing about how it fluctuates,” Byrne said.
“The direction of heat and salt in the ocean is very important because it controls rainfall and determines the climate,” Byrne said.
Studying the sea
Byrne’s research was among the topics discussed by several hundred scientists in Portland this past week at a biannual ocean science meeting sponsored by the American Geophysical Union.
Much of the discussion was about new ways of collecting information about the sea, like Byrne’s project.
Some measurements that are relatively easy and routine on land are extremely difficult at sea, even something as simple as measuring rainfall.
But University of Washington oceanographer Jeffrey Nystuen, who trained as a physicist, came up with a way to use the sound made by raindrops to estimate rainfall on sections of the ocean.
“Bubbles trapped in the splash of raindrops ring like tiny bells,” Nystuen said. “So the sound of even light drizzle is really quite loud.”
Submerged hydrophones record the sound of rainfall, storing it until the devices bob to the surface and transmit the data or are retrieved by ships. A computer program breaks down the sound to determine the pattern of rainfall and estimate its volume, he said.
The scientists hope their collective efforts with new technology will pay off with advances in many areas of research, ranging from biomedical research to earthquake prediction.
“The exciting thing about this meeting is that it brings together so many diverse groups of scientists to look at problems from a multidisciplinary perspective,” said Douglas Biggs of Texas A&M University, who is researching ways to protect endangered sperm whales by reducing the noise created by undersea oil and gas exploration.
“We used to be doing it just with ships, and now we’re doing it with everything from computers to satellites,” Biggs said.