Contents - Winter 2008
Vol. 1 No. 1
Extreme Storm Warnings—Forecasting Space Weather
By Mari-Louise Rowley
What causes the northern lights?
Solar winds, or flows of hot plasma from the Sun, cause magnetic storms in the magnetosphere. They release high voltage primary electrons from space that collide with neutral molecules and knock off electrons, creating more positively charged molecules, or ions, and secondary electrons. The huge amplification of charged particles created by incoming electrons causes the brilliant visual display of northern lights. During a typical geomagnetic storm, 50 gigawatts of power can deluge Earth’s ionosphere. By comparison, SaskPower’s total generating capacity in 2006 was a fraction of this—3,660 megawatts.
Aurora seen in Tromso, Norway while running experiments on the EISCAT (European Incoherent Scatter Radar). Photo courtesy Darren Wright, University of Leicester.
Contrary to the image of a cold, empty vacuum, outer space is a tumultuous place, with ferocious storms that can knock out satellites, endanger astronauts and blow out power grids on Earth.
Instead of winds and storms driven by high and low pressure systems, which we experience on Earth, the weather in space is a churning miso soup of plasma—electrically charged gas driven by high and low voltage systems.
Space weather, fuelled by energetic particles and radiation from the Sun, can cause massive power outages, pipeline corrosion and radio blackouts, and can degrade GPS positioning and increase radiation dosage to airline pilots and passengers. The radiation can penetrate spacecraft and spacesuits, damage equipment and bombard satellites, wreaking havoc with electronic systems.
Accurate forecasts of space weather are crucial for global communications and commerce. There are roughly 800 satellites in space, each worth about $200 million. With hardware alone totalling $160 billion and daily business transactions in the hundreds of millions to billions of dollars, there is a lot at stake.
But forecasting space weather—a critical area of research for University of Saskatchewan physicists—turns out to be just as challenging as forecasting Earth weather, and involves measuring and analyzing the volatile flux and flow of charged particles in space.
“This research is particularly important for Canada, because northern communities are most strongly affected by space weather,” says Kathryn McWilliams, U of S assistant professor of physics and engineering physics.
McWilliams is part of an international consortium of researchers who study and monitor extreme weather events in space.
Kathryn McWilliams. Photo courtesy Debra Marshall.
“What most people don’t realize is the extent to which our daily activities depend upon telecommunications satellites. Telephone, television, banking and the Internet are all controlled by satellites, which in turn are affected by space weather.”
–U of S space and atmospheric scientist Kathryn McWilliams
The tools they use are a network of high frequency radars, which measure the velocity and voltage of electrically charged particles hurtling through the ionosphere, more than 100 kilometres above Earth.
A network of 19 radars, 12 in the Arctic and seven in the Antarctic, measure electrical activity where it is most intense—and where northern and southern lights are most resplendent. Radars are paired to accurately measure the velocity and voltage of charged particles.
With funding from the Canadian Space Agency, NSERC and the U.S. National Science Foundation, McWilliams is a key member of the U of S team that is setting up new radars in Inuvik, which will pair with the radar set up in Rankin Inlet in 2006. These new radars comprise PolarDARN, the first SuperDARN (Super Dual Auroral Radar Network) radars to study space weather over the polar caps.
The aurora borealis is a manifestation of electromagnetic storms, a phenomenon U of S researchers with the Institute of Space and Atmospheric Studies have been studying for decades.
PolarDARN radar building and towers at Rankin Inlet with aurora in background (to the south). Photo courtesy Mikko Syrjäsuo.
“The aurora occurs in a big ring around the northern and southern magnetic poles,” explains McWilliams. “The area directly over the polar caps appears pretty dark, so for ages scientists thought nothing much of interest happened there. In fact, that is the area where Earth’s magnetic field is connected directly to the solar winds that cause the aurora.”
Northern lights originate in the ionosphere, the transition zone where the Earth’s atmosphere of neutral oxygen and nitrogen gases meets the electrically charged gases in space.
PolarDARN radars measure the motion of the ionosphere’s charged particles, which are connected to the magnetic field lines that stretch out into space. In effect, these magnetic lines act like the line of a fishing rod. When there is a bite—or in this case, a disturbance above from the Sun—it is detected along the line almost instantaneously.
Main antenna array of SuperDARN radar just outside Saskatoon. Photo courtesy Kathryn McWilliams.
“Imagine filling up a water balloon. The solar wind fills the magnetosphere with energy, particles and momentum to the point where it wants to explode. Here, the explosion is a massive release of energy that we see as an aurora,” says McWilliams.
“What PolarDARN allows us to study is the filling-up process, which is simpler, because it is not as chaotic or explosive a phenomenon to look at.”
Student Marian Thorpe working on Inuvik radar. Photo courtesy Kathryn McWilliams.
McWilliams’ speciality is assimilating studies from a wide range of instrumentation. As well as SuperDARN measurements, she uses images of the ultraviolet aurora seen from space, images of the visible aurora seen from the ground, and observations of magnetic fluctuations and solar wind.
She is quick to credit her students: Marian Thorpe, a summer student who helped with the Inuvik radar installation, and M.Sc. student Jeff Pfeifer and summer student William Brenna, who are both writing software and doing data analysis. “The summer students are both first-year students and the job they are doing is incredible,” says McWilliams, noting all the instrumentation, equipment and much of the software for their experimentation is built from scratch.
McWilliams began her career with a summer job under George Sofko, principal investigator of the Canadian SuperDARN.
“In Saskatchewan, we are all interested in weather; you can see it coming for hours,” she says. “The opportunity to work with George and study space weather and the northern lights was amazing.”
SuperDARN studies will be part of International Polar Year (2007-2008), when scientists from around the world collaborate to expand exploration and scientific knowledge of polar regions. “This is one of the most successful international space science programs to date. My students and I are thrilled to be a part of it.”
Pearl Harbor and ISAS Share Historic Radar
The original radar used for auroral studies by the U of S Institute of Space and Atmospheric Sciences (ISAS) was the same one that detected the Japanese fleet moving in on Pearl Harbor—warnings that were ignored at the time.
ISAS, founded in 1957 by Prof. Balfour Currie, was the first U of S institute and the first “space and atmospheric science” institute in Canada.
“Balfour told his friend Nate Gerson in the U.S. military that we wanted to study the aurora, and he loaned us our first radar,” recollects U of S atmospheric physicist George Sofko. “All we had to do was pay transportation costs.”
The radar was eventually tracked down in Saskatoon in 1991 and sent to the Westinghouse Historical Electronic Museum, where it now resides.
Since then, ISAS, which celebrated its 50th anniversary this past year, has become an international leader in space and atmospheric environmental research, space weather, and climate studies.
The institute has produced several successful spinoff companies. SED Systems—now a world leader in satellite communications technology—originated in 1965 as a division of ISAS.
