Scientists have discovered new evidence about how Earth’s magnetic field interacts with the solar wind, a finding that may help improve forecast of space weather which affects our communication and power systems.
Researchers at the Virginia Polytechnic Institute and State University (Virginia Tech) collected data from six stations across East Antarctic Plateau.
Although invisible to the naked eye, space weather can have serious, detrimental effects on modern technological infrastructure, including telecommunications, navigation and electrical power systems.
The researchers for the first time observed that regardless of the hemisphere or the season, the polar ionosphere is subject to a constant electrical current, produced by pressure changes in the solar wind.
“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 Robert Clauer, a professor at Virginia Tech.
These space weather observations allow researchers to watch how the behaviour of the Sun and the solar wind – an unbroken supersonic flow of charged particles from the Sun – changes over time and how Earth’s magnetic field responds to solar wind variations. The observations help build a detailed, reliable model of space weather.
They hope that eventually space weather forecasting will become as reliable as today’s winter storm warnings.
Researchers installed six autonomous data-collection stations along the 40-degree magnetic meridian (longitude), deep in the southern polar cap areas under the auroras.
The stations, located in the harsh environment of the remote East Antarctic Plateau, are the Southern Hemisphere counterpart to a magnetically similar chain in Greenland.
Researchers have been monitoring the electric current systems in the magnetosphere – specifically currents that connect to the ionosphere.
“The solar wind interacts with Earth’s magnetic field in a manner similar to a fluid, but an electrically conducting fluid,” Clauer said. A chain of data-collection stations in Greenland allowed researchers to take measurements in the Northern Hemisphere. 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.
The stations are powered by solar cells in the months-long Antarctic summer, and by lead-acid batteries during winter. The stations 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.