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New instrumentation helps scientists better predict space weather
James E.
Kloeppel, Physical Sciences Editor
217-244-1073; kloeppel@uiuc.edu
Released
12/11/2006
|
CHAMPAIGN, Ill. —
New instrumentation and observing techniques, being developed by researchers
at the University of Illinois at Urbana-Champaign, are helping scientists
better understand and predict space weather.
Space weather can be caused by giant solar flares and coronal mass ejections
from the sun, and can adversely affect life on Earth. Tremendous blasts
of radiation may threaten astronauts, disrupt satellite communication
and navigation systems, and knock out power grids on Earth. Near Earth’s
magnetic equator, however, space weather can have dramatic effects even
during quiet solar conditions.
“These storms are among the most explosive events that occur in
the ionosphere, and are an important component of ongoing space weather
research,” said Jonathan Makela, a professor of electrical
and computer engineering at Illinois.
“A better understanding of the physical processes responsible
for these storms could improve our ability to forecast space weather,”
Makela said, “and lead to better techniques to mitigate its effects.”
The ionosphere extends from approximately 100 kilometers to more than
1,000 kilometers above Earth’s surface. In this region of the
atmosphere, solar radiation can strip the outer electrons from atoms
and molecules of gas. After sunset, the electrons recombine and give
off light, called airglow. Space weather events at the magnetic equator
appear as depletions in the airglow. As signals at radio wavelengths
pass through these turbulent regions, they scintillate – much
like the twinkling of starlight at optical wavelengths.
Unlike aurora, which can be seen with the naked eye, airglow near the
magnetic equator is visible only in photographs taken through narrow-band
filters with exposure times of a minute or two.
In August 2006, Makela installed a narrow-field ionospheric airglow
imager at Cerro Tololo Inter-American Observatory, located east of La
Serena, Chile. The imager looks north, parallel to Earth’s magnetic
field and toward the magnetic equator. Two GPS scintillation monitors
were also installed at the site, and are used to study ionospheric instabilities
at a smaller size scale.
“The GPS monitors allow us to perform simple interferometric calculations
and derive drift velocities of the perturbations that cause the scintillations,”
Makela said. “By measuring power fluctuations in the GPS signals,
we can also correlate the scintillation patterns with the airglow images.”
Makela is also attempting to correlate his airglow images with radar
backscatter observations made with the Jicamarca radar system near Lima,
Peru.
“In this way, we can study the relative roles of the equatorial
and local regions of the ionosphere in the production of scintillation-causing
perturbations,” Makela said. “This could then help us better
predict space weather, prepare further safeguards on Earth and in space,
and plan more robust communication and navigation schemes during space
weather events.”
Makela will describe the instrumentation and present early results,
based on overlapping data from the imager, GPS receivers and Jicamarca
radar, at the American Geophysical Union meeting in San Francisco, Dec.
11-15.
Makela’s work in Chile is in collaboration with electrical and
computer engineering professors Paul Kintner at Cornell University and
Brent Ledvina at the Virginia Polytechnic Institute and State University.
Illinois graduate student Ethan Miller is also working on the project.
The National Science Foundation and the U.S. Naval Research Laboratory
funded the research.
Editor’s note: To reach Jonathan Makela,
call 217-265-9470; e-mail: jmakela@illinois.edu.
