12 December 2013

What to expect when the sun’s ejecting: forecasting space weather from coronal mass ejections

Posted by pweiss

Above Taken by a NASA satellite on August 20, this image shows coronal mass ejection arcing away from the sun — the dark central circle.  Image Credit: ESA & NASA/SOHO, SDO Below The space weather conditions near Earth on Wednesday provided by the UCSD team. More material from solar ejections is contained within the darker orange regions. Image Credit: UCSD Center for Astrophysics and Space Sciences/Solar-Terrestrial Environment Laboratory (Japan)

Above: Taken by a NASA satellite on August 20, this image shows coronal mass ejection arcing away from the sun — the dark central circle. Credit: ESA & NASA/SOHO, SDO Below: The space weather conditions near Earth on Wednesday provided by the UCSD team. More material from solar ejections is contained within the darker orange regions. Credit: UCSD Center for Astrophysics and Space Sciences/Solar-Terrestrial Environment Laboratory (Japan)

When whorls of plasma clouds erupt away from the sun in events known as coronal mass ejections, the portions that reach Earth can create terrestrial spectacles. These sun storms fuel stunning auroras in the night sky, but they can also foul up communication networks and Global Positioning Systems. Researchers at the University of California, San Diego have developed a method to better forecast these storms before they hit Earth.

“When a hurricane happens, you want to know if it’s headed for your door,” said heliospheric scientist Hsiu-Shan Yu Wednesday morning at the American Geophysical Union’s Fall Meeting in San Francisco. Presenting a poster on her group’s recent findings, she said the same rationale applies to solar storms.

While satellites capture dazzling images of coronal mass ejections, photos squish three-dimensional phenomena onto two-dimensional film. Yu and her adviser, Bernard Jackson, build three-dimensional pictures of solar storms in real-time.

From these 3D reconstructions, the team can visualize a solar storm from every angle. For instance, when viewed head-on, a November 2011 coronal mass ejection looked like it would bombard the Earth with electromagnetic radiation and high-energy ions. But a side view revealed that the storm would die off before reaching the planet.

“It’s like when we go to the hospital to get tomography for our bodies,” Yu said, referring to methods like CT scans that assemble 3D images of internal organs and tissues. “It gives you an overall picture.”

The group can also extract how much ejected solar material is earthbound and how fast it’s moving. They can then forecast how intense a solar storm will be, along with if and when it will hit Earth.

To do this, the team had to develop a homegrown forecasting method. Jackson said their algorithm correlates better with observations than the current method used by the National Oceanic and Atmospheric Administration to predict space weather. Because of this, the South Korean Space Weather Center now uses both the UCSD model and the NOAA method, said Jackson.

To build their 3D reconstructions of solar storms, the group “images” the space between the Earth and sun with telescopes that sense radio waves rather than light waves. By stitching together a series of 2D radio images, an automated system devised by the UCSD team creates an ever-evolving 3D model of the storm.

The system collects data from three radio telescopes in Japan and assembles a 3D picture whenever new data is available. The group posts up-to-date space weather maps and movies on its website.

However, only one of the telescopes is currently running. Yu said the other two are located on mountain ranges and are not maintained during the winter. This impedes the group’s ability to predict the speed of solar storms. While Yu is currently working on ways to improve forecasts coming from a single telescope, Jackson hopes to expand the project to gather more data and erase this seasonal dependency.

“We’re working with existing groups to put [existing radio telescopes] together into a bigger project,” he said. “We’re trying to get everyone on the same page.”

- Matt Davenport is a science communication graduate student at the University of California, Santa Cruz