Breathing of Earths upper atmosphere linked to solar wind disturbances

December 16th, 2008 - 4:56 pm ICT by ANI  

Washington, Dec 16 (ANI): A new study by researchers at the University of Colorado at Boulder has shown that the periodic breathing of Earths upper atmosphere, which has long puzzled scientists, is due in part to cyclic solar wind disturbances.

The finding should help engineers track satellites more accurately and improve forecasts for electronic communication disruptions.

According to Aerospace engineering sciences department Associate Professor Jeff Thayer, the outer, gaseous shell of the atmosphere, known as the thermosphere, is known to expand and contract as it exchanges energy with the space environment, causing changes in thermosphere density.

Changes in thermosphere density can alter the atmospheric drag of satellites, causing them to deviate from their predicted paths and complicating tracking and orbital adjustment maneuvers, he added.

While extreme ultraviolet radiation from the sun is the dominant mechanism that causes the thermosphere to breathe, the new CU-Boulder study indicates high-speed wind from the sun triggers independent breathing episodes by creating geomagnetic disturbances, heating the thermosphere and altering its density.

The wind streams are generated by relatively cool pockets on the suns surface known as solar coronal holes that periodically rotate around the suns surface, according to Thayer.

We were surprised to find the density changes were so consistent in our observations, said Thayer, lead study author.

Because of the huge increase in satellite activity in recent years, finding this new thermosphere breathing mechanism should help improve our models and increase the accuracy satellite tracking and collision avoidance, he added.

The thermosphere begins at about 60 miles above Earth and extends to about 300 miles in altitude.

The thermosphere gas is known to expand and contract on a 27-day solar rotation period due to changes in extreme UV radiation, according to Thayer.

The new findings indicate the thermosphere also has periodic oscillations occur at four-to-five days, six-to-seven days and nine-to-11 days caused by the violent effect of the high-speed soar winds interacting with Earth and transferring energy through auroras and enhanced electric currents.

In addition to helping monitor density changes in the thermosphere, the new findings should help researchers track the growing amount of space debris in the upper atmosphere that can damage satellites and threaten astronauts. (ANI)

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