"Earth-Shaking" Surprise Found in Upper Atmosphere
Thursday, Jan 7, 2010 | Updated 2:43 PM PST
NASA
This highly oblique image of northwestern African captures the curvature of the Earth and shows its atmosphere.
A half-century-old mystery about how the solar wind interacts with earth's atmosphere may have been partly solved by some UCLA atmospheric scientists.
As a result spacecraft, power grids and other modern facets of life could be made safer.
Researchers have for the first time discovered that the solar wind, a stream of energized particles that flows out from the sun, varies greatly in how it affects the earth's magnetosphere.
The rate at which the solar wind transfers energy to the magnetosphere -- a highly magnetized region which surrounds and protects the Earth -- can vary widely, but what determines the rate of energy transfer was unclear, according to UCLA atmospheric scientists.
"We thought it was unknown, but we came up with a major surprise," said UCLA professor Larry Lyons.
Lyons said Heejong Kim, an assistant UCLA researcher and their colleagues analyzed radar data that measure the strength of the interaction by measuring flows in the ionosphere, the part of the Earth's upper atmosphere ionized by solar radiation. The results surprised them.
Charged particles carry currents, which cause significant modifications in the Earth's magnetosphere. This region is where communications spacecraft operate and where the energy releases in space known as substorms wreak havoc on satellites, power grids and communication systems.
"Any space physicist, including me, would have said a year ago there could not be substorms when the interplanetary magnetic field was staying northward, but that is wrong," Lyon said in a news statement. "Generally, it's correct, but when you have a fluctuating interplanetary magnetic field, you can have substorms going off once per hour."
The magnetosphere was discovered in 1957. By the late 1960s, it had become accepted among scientists that the energy transfer rate was controlled predominately by the interplanetary magnetic field, the Sun's solar wind which
carries the particles from the Sun's magnetic field to the Earth, taking about three or fours to reach the planet.
"It's like something else is heating the atmosphere besides the Sun," Lyon said. "This discovery is like finding it got hotter when the sun went down.
"We were looking to do something else, when we saw life is not the way we expected it to be. The most exciting discoveries in science sometimes just drop in your lap.
"In our field, this finding is pretty earth-shaking. It's an entire new mode of energy transfer, which is step one. The next step is to understand how it works. It must be a completely different process."
Lyons said he and Kim used radar measurements to study the strength of the interaction between the solar wind and the Earth's magnetosphere.
"The National Science Foundation's radars have enabled us to make this discovery," he said. "We could not have done this without them."
