Physicists have just detected the smallest bubbles in our oceans.
Bubbles ring like bells and deflect light in predictable and testable ways, allowing researchers to examine their size.
The research could help to explain how gas is hiding out in the water, and how climate and sea life may be affected as a result.
For the first time, the smallest bubbles in the oceans -- as tiny as one thousandth of a millimeter -- have been detected, say physicists.
If they are right, the researchers may be on their way to unraveling one of the more nagging mysteries in oceanography: How much gas is hiding out in the oceans, and how might it affect Earth's climate and sea life? Their work may even be able to explain further how sound and light travels underwater.
By both looking and listening for tiny bubbles in the ocean near Hawaii, researchers think they have pinned down the signatures of tiny bubbles at a range of sizes. This all works because bubbles ring like bells and deflect light in predictable and testable ways.
To test for the ringing acoustic signatures of tiny bubbles, physicist Helen Czerski of University of Rhode Island has devised a specially-designed echo chamber about the size of a soccer ball. Ocean water rushes into the chamber and is exposed to many frequencies of sound to see what sizes of the bubbles within. The smaller the bubbles, the higher the frequency at which they begin ringing back in the chamber.
"So we listen for the echoes at all these frequencies," Czerski told Discovery News. In the actual experiment in Hawaii the echo chamber was dunked off the back of a boat to gather data on the bubbles in the ship's wake. It was also left attached to a buoy for weeks, where it recorded passing clouds of bubbles made by breaking wind waves.
Right alongside of Czerski's device was another bubble detector that looked for size-specific optical signatures of bubbles. By comparing the data from both instruments, the researchers are able to confirm the presence of the tiny bubbles.
"The bubbles affect how light propagates through water," explained oceanographer Michael Twardowski of the company WET Labs. "Different sizes of bubbles scatter light in different ways."
The manner in which light is scattered allows detection of bubbles down to less a thousandth of a millimeter, or a micron in diameter. It also affects the color of the ocean water as seen from space. As a result, the optical work helps in making better sense of satellite data collected on the ever-changing colors of the oceans.
"In general, the data match pretty well," said Czerski.
These bubbles are an important means of carrying gases from the atmosphere into the oceans, Czerski told Discovery News. One-half of the atmospheric carbon dioxide, for instance, is thought to enter the sea. Some bubbles are also created by bacteria in the oceans, she said. These can contain waste products of bacteria: sulfur compounds that are known to serve as the seeds of clouds in the atmosphere.
"So the chemistry (of the bubbles) is really important for climate models," said Czerski, whose research is funded by the Office of Naval Research.