Sun Induces Strange 'Breathing' of Earth's AtmosphereDecember 15, 2008
SAN FRANCISCO, California - New satellite observations have revealed a previously unknown rhythmic expansion and contraction of Earth's atmosphere on a nine-day cycle.
This "breathing" corresponds to changes in the sun's magnetic fields as it completes rotations once every 27 days, NASA and University of Colorado, Boulder, scientists said Monday at the American Geophysical Union annual meeting.
The sun's coronal holes, seen as dark regions in the image above, direct plasma away from the sun and out into the solar system. When these particles get to the Earth, they heat the upper atmosphere, causing the outer atmosphere to expand and contract.
"What's going on in the solar side is indeed mysterious and challenges the solar physics understanding," said Stan Solomon, a scientist at the National Center for Atmospheric Research who was not involved in the research.
The finding emphasizes the many ways that solar activity impacts the Earth - and its increasingly space-utilizing humans.
"From the Earth's perspective, we're in the sun's outer atmosphere," said Jeffrey Thayer, an aerospace engineer at UC-Boulder.
The new discovery could help scientists and engineers design better satellites that account for the changing conditions in the ionosphere. Eventually, it might be possible to predict the severity of ionospheric storms and protect the world's communication infrastructure.
The scientists used changes in the density of the Earth's atmosphere to pinpoint this previously unknown pattern. As the atmosphere contracts or expands, it also gets more or less dense, respectively. In response to the "hills and valleys of density," satellites subtly speed up or slow down, recording those motions with on-board accelerometers. And that's the data that allowed the scientists to back into the discovery of this new atmospheric cycle.
Solomon said that while the cycle on Earth is interesting, the really strange aspect of this work is what it says about our local star.
"What's going on in the sun that's causing all this?" Solomon said. "It's not entirely clear. That part of it is quite mysterious."