New type of ocean current discovered
Scientists have discovered a zebra-stripe pattern of deep, wide and slow currents that cut east-west across the planet's oceans, each like a plodding conveyer belt at the airport passenger terminal.
The previously unsuspected currents stand in sharp contrast to the heat- and wind-driven express trains such as the Gulf Stream, which typically flow in a circular pattern.
The findings on this ocean's hidden texture will be published in an upcoming issue of the Geophysical Research Letters by a team of four scientists that includes a researcher and a postdoctoral fellow from the University of Hawaii at Manoa.
Using data from satellites and drifting buoys, the scientists found that weak but persistent currents run horizontally across oceans worldwide, moving particles east or west.
Their cause remains a mystery.
Eventually, the currents, or striations, could explain how nutrients move through sea water and boost marine life, and also might explain the effect of the ocean current on climate, the scientists said.
"These are jetlike features," said Nikolai Maximenko, one of the authors and a researcher with the UH International Pacific Research Center. "We suspect that they must contribute significantly to mixing in the ocean and to earthly interaction, which is important for climate systems."
Contributing author Peter Niiler of the Scripps Institution of Oceanography in San Diego said future models of climate systems will eventually show the striations.
The discovery started with work by Niiler, who for 20 years had been collecting data from 11,000 drifting buoys in the world's oceans. Monitoring data from the buoys, Niiler and Maximenko noticed strange currents in 2003.
Maximenko, along with UH postdoctoral fellow Oleg Melnichenko, selected two regions for closer analyses in the Pacific: near California and toward Latin America.
The two Hawaii scientists analyzed historical data from satellites and of the altitude and wind. They used a filter to remove "noise" from the data and produced an image of the currents, which also have crests and troughs a few centimeters high.
Dozens of previous research missions in those areas missed the currents, Maximenko said.
One reason might be their weakness.
With a speed of about .02 mph or 1 centimeter a second, they are dwarfed by normal ocean currents and eddies, some of which have speeds of about 30 centimeters a second near Hawaii. To continue the airport metaphor, people running on a conveyer belt attract more attention than the conveyer belt itself.
While weak, the currents persist and can move as much water as swirling eddies in the ocean, said Maximenko, adding, "They are always there."
Scientists also found the currents travel nearly half a mile down, possibly even reaching the sea floor. While feeble, the currents are about 124 miles wide and travel thousands of miles.
Scientists are still trying to explain their existence. One theory compares the striations to cloud bands on Jupiter that form from turbulence in the atmosphere. Maximenko considers this theory unlikely, since land masses interfere in the ocean.
The scientists plan another study, funded by NASA and with more scientists added to the team, that will try to determine the cause of the stripes and their effects.