July 21, 2009

Dust Cloud Circled The Entire Globe

A Japanese study using a NASA satellite found that dust clouds being generated by a huge dust storm in China's Taklimakan desert in 2007 made more than one full circle around the globe in just 13 days.

Once the cloud reached the Pacific Ocean the second time, it descended down and deposited some of its dust into the sea, revealing how a natural phenomenon can impact the environment far away.

"Asian dust is usually deposited near the Yellow Sea, around the Japan area, while Sahara dust ends up around the Atlantic Ocean and coast of Africa," said Itsushi Uno of Kyushu University's Research Institute for Applied Mechanics.

"But this study shows that China dust can be deposited into the (Pacific Ocean)," he told Reuters by telephone. "Dust clouds contain 5 percent iron, that is important for the ocean."

Scientists wrote in a paper published in Nature Geoscience that they used a NASA satellite to describe how mathematical modeling to track and measure the movement of the dust cloud, which formed after the dust storm on May 8-9 in 2007.

The desert is located in the Chinese northwestern region of Xinjiang.

Uno, who led the research, and the other scientists found that the dust clouds were lifted 5-6 miles above the earth's surface and transported over one full circle around the earth.

"The most important achievement is that we tracked this through one full circuit round the globe, nobody has done this before. After half a circuit, usually the dust concentration gets very low and you can't track it," Uno told Reuters.

"This means that dust concentration, dust lifetime is very long, more than two weeks."

The dust cloud measured about 1.9 miles vertically and 1,200 miles horizontally, and it stayed that way after one full trip around the world.

Researchers think that dust particles trigger the formation of high-altitude cirrus clouds, although experts do not know whether these clouds warm or cool the earth.

NASA image courtesy MODIS Rapid Response Team, Goddard Space Flight Center.


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