Almost as soon as Virginia Tech researchers finished installing six data collection stations near the South Pole in January, their data provided new evidence regarding a controversial scientific phenomenon about Earths magnetic field and space weather.
Space weather is driven by solar wind an unbroken, highly variable, supersonic flow of charged particles exploded from the sun. When solar wind beats against the magnetic field surrounding the planet, it can create beautiful auroras, as well as electromagnetic impulses that can negatively affect navigation systems, telecommunications, and power grids.
"The solar wind interacts with Earths magnetic field in a manner similar to a fluid, but an electrically conducting fluid," described Robert Clauer, a professor of electrical and computer engineering (ECE) at Virginia Tech, who heads the Magnetospheric Ionospheric Science Team.
His team has been monitoring the electric current systems in the magnetosphere — specifically currents that connect to the ionosphere. This region in the upper atmosphere is ionized -- stripped of electrons by solar radiation. When it's summer in the Northern Hemisphere, there is more direct sunlight on the atmosphere, which means more atoms are ionized. This phenomenon creates a highly conductive environment in the summer months, and a poorly conductive one in the winter.
A chain of stations in Greenland allowed researchers to collect data in the Northern Hemisphere. Until recently, these data were divided into summer and winter, and the information gathered during the winter months was used to approximate what was happening in the Southern Hemisphere during the northern summer.
"We didn't have a full picture of what was happening in the space environment because we could only observe one hemisphere, but magnetic field lines are connected to both hemispheres," said Clauer. "It was important that we look at them simultaneously."
So, armed with a $2.66 million grant from the National Science Foundation, Clauer and his team designed and hand-built six data collection stations, and installed them, piece by piece, at the South Pole, initially for testing. Over an eight-year period, they placed them along the 40-degree magnetic meridian (longitude), deep in the polar cap areas under the auroras. These new stations -- in the harsh environment of the remote east Antarctic plateau -- are the southern counterparts to the Greenland chain.
"This was a very challenging project, to deploy sophisticated instrumentation in such remote locations," Clauer said.
The stations run autonomously and are powered by solar cells in the Antarctic summer and lead-acid batteries during winter. They contain a collection of instruments, including a dual-frequency GPS receiver that tracks signal changes produced by density irregularities in the ionosphere, and two kinds of magnetometers that measure the varying strength and direction of magnetic fields. The data is transmitted to Blacksburg, Virginia, via iridium satellites.
In January, the team completed installing the final station in the chain. Now, data from the complete chain in the Southern Hemisphere joins with data from the Northern Hemisphere. For the first time, observations confirmed that regardless of the hemisphere or the season, waves on the boundary of the magnetosphere produced by solar wind pressure changes are linked to both the northern and southern ionospheres by electric currents of the same magnitude.
"It's a bit of a surprise, because when you have a current, you usually expect a voltage relationship, where resistance and current are inversely related: high resistance equals small current; low resistance equals large current," said Clauer.
Instead, Clauer's team observed that the ionosphere -- southern, northern, winter, summer -- is subject to a constant current.
"This finding is a new part of the physics that we need to understand and work with," said Clauer.
Clauers team will continue collecting information from both sets of data stations. They hope to be operational throughout the 11-year solar activity cycle, depending on snow accumulation. They will be watching how the behavior of the sun and the solar wind changes over time, and how the earths magnetic field responds to variations -- all with the goal of building a detailed, reliable model of space weather.
Clauer hopes that reliable space weather forecasting will become as important for telecommunications, navigation, and power systems as today's winter storm warnings are for school systems.
Virginia Tech team members include Michael Hartinger, research assistant professor of ECE; Zhonghua Xu, research scientist; Kshitija Deshpande (Ph.D. 14), post-doctoral associate; Dan Weimer, research professor of ECE; and graduate student Taikara Peek of Rochester, New York. Previous participants include Rick Wilder (Ph.D. 11), Joseph Macon (MEng 13), and Lyndell Hockersmith, a former master's student.