Technology Science - Space weather forecasts get a boost
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An image from NASA's Solar Dynamics Observatory shows a solar flare, which was accompanied by a spectacular coronal mass ejection (CME) on June 7, 2011. (NASA)Newly developed techniques will allow scientists to better predict the size and arrival time of solar storms that could damage satellites, cause GPS navigation to malfunction and knock out power grids on Earth.
Alysha Reinard, a research scientist at the U.S. National Oceanic and Atmospheric Administration’s space weather prediction centre, says that up until now, forecasters could only predict within 12 to 14 hours when a coronal mass ejection or CME â€Â" a blast of plasma launched by the sun â€Â" would hit Earth.
The fast-moving, billion-tonne plasma cloud interacts with the Earth’s magnetic field and atmosphere to generate geomagnetic storms that affect electronic equipment.
“It’s good to know in advance so we can warn people who use these technologies that there could be problems,†Reinard said at a NASA news conference Thursday.
NASA’s pair of STEREO observatories, launched in 2006, have now improved forecasts to within eight hours.
And with a new technique announced by NASA Thursday, “we think… we can do any better than that,†said Reinard at a news conference.
The STEREO spacecraft travel in the same orbit as Earth around the sun, but one travels ahead of the Earth and the other travels behind, so that they get two different views of the sun.
The new solar storm tracking technique, developed by the team of Craig DeForest at the Southwest Research Institute in Boulder, Colo., teases out the faint signals of the CME, recorded by the STEREO spacecraft, from the background starlight to allow scientists to follow the cloud from the sun’s corona to the Earth. That allows scientists to pinpoint both its mass and its arrival time.
DeForest’s team published their results, which track a CME launched in 2008, in the Astrophysical Journal this week.
Reinard said that in the past, two challenges made space weather forecasting difficult:
- Measurements of the CME were made by an instrument close to the sun, and the CME could speed up or slow down on its way to the Earth, making predictions inaccurate.
- The most damaging CMEs are coming straight toward the Earth, and their speed is difficult to measure head-on.
The STEREO spacecraft overcome both those problems because they are closer to the Earth, but get a side view of the CME due to their positioning.
Solar activity such as flares are expected to increase as we move toward the peak of the 11-year solar cycle, which is expected in 2013.
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