Jacques van Oene
December 5th 05, 04:11 PM
December 5, 2005
George Deutsch/Erica Hupp
Headquarters, Washington
(202) 358-1324/1237
Bill Steigerwald/Rachel Weintraub
Goddard Space Flight Center, Greenbelt, Md.
(301) 286-5017/0918
RELEASE: 05-419
NASA AND NSF CREATE UNPRECEDENTED VIEW OF UPPER ATMOSPHERE
Scientists from NASA and the National Science Foundation discovered a
way to combine ground and space observations to create an
unprecedented view of upper atmosphere disturbances during space
storms.
Large, global-scale disturbances resemble weather cold fronts. They
form in the Earth's electrified upper atmosphere during space storms.
The disturbances result from plumes of electrified plasma that form
in the ionosphere. When the plasma plumes pass overhead, they impede
low and high frequency radio communications and delay Global
Positioning System navigation signals.
"Previously, they seemed like random events," said John Foster,
associate director of the Massachusetts Institute of Technology's
Haystack Observatory. He is principal investigator of the Foundation
supported Millstone Hill Observatory, Wesford, Mass.
"People knew there was a space storm that must have disrupted their
system, but they had no idea why," said Tony Mannucci, group
supervisor of Ionospheric and Atmospheric Remote Sensing at NASA's
Jet Propulsion Laboratory, Pasadena, Calif. "Now we know it's not
just chaos; there is cause and effect. We are beginning to put
together the full picture, which will ultimately let us predict space
storms."
Predicting space weather is a primary goal of the National Space
Weather Program involving NASA, the foundation and several other
federal agencies. The view researchers created allowed them to link
movement of the plumes to processes that release plasma into space.
"Discovering this link is like discovering the movement of cold
fronts is responsible for sudden thunderstorms," said Jerry
Goldstein, principal scientist at the Southwest Research Institute,
San Antonio.
Since the occurrence of plasma plumes in the ionosphere disrupts GPS
signals, they provide a continuous monitor of these disturbances.
Researchers discovered a link between GPS data and satellite images
of the plasmasphere. The plasmasphere is a plasma cloud surrounding
Earth above the ionosphere. It is being observed from NASA's Imager
for Magnetopause to Aurora Global Exploration satellite. The
researchers discovered the motion of the ionospheric plumes
corresponded to the ejection of plasma from the plasmasphere during
space storms.
The combined observations allowed construction of an underlying
picture of the processes during space storms, when the Earth's
magnetic field is buffeted by hot plasma from the sun. As the solar
plasma blows by, it generates an electric field that is transmitted
to the plasmasphere and ionosphere. This electric field propels the
ionospheric and the plasmaspheric plasma out into space. For the
first time, scientists can directly connect the plasma observed in
the ionosphere with the plasmasphere plumes that extend many thousand
of kilometers into space.
"We also know these disturbances occur most often between noon and
dusk, and between mid to high latitudes, due to the global structure
of the electric and magnetic fields during space storms," said Anthea
Coster of the Haystack Observatory. "Ground and space based, and in
situ measurements are allowing scientists to understand the
ionosphere-thermosphere-magnetosphere as a coupled system."
The plumes degrade GPS signals in two primary ways. First, they cause
position error by time delaying the propagation of GPS signals.
Second, the turbulence they generate causes receivers to lose the
signal through an effect known as scintillation. It is similar to the
apparent twinkling of stars caused by atmospheric turbulence.
Researchers are presenting the findings today during the American
Geophysical Union meeting in San Francisco, Calif. For information
about space weather and other research on the Web, visit:
http://www.nasa.gov/vision/universe/solarsystem/cold_front.html For
information about NASA and agency programs on the Web, visit:
http://www.nasa.gov/home
-end-
--
--------------
Jacques :-)
www.spacepatches.info
George Deutsch/Erica Hupp
Headquarters, Washington
(202) 358-1324/1237
Bill Steigerwald/Rachel Weintraub
Goddard Space Flight Center, Greenbelt, Md.
(301) 286-5017/0918
RELEASE: 05-419
NASA AND NSF CREATE UNPRECEDENTED VIEW OF UPPER ATMOSPHERE
Scientists from NASA and the National Science Foundation discovered a
way to combine ground and space observations to create an
unprecedented view of upper atmosphere disturbances during space
storms.
Large, global-scale disturbances resemble weather cold fronts. They
form in the Earth's electrified upper atmosphere during space storms.
The disturbances result from plumes of electrified plasma that form
in the ionosphere. When the plasma plumes pass overhead, they impede
low and high frequency radio communications and delay Global
Positioning System navigation signals.
"Previously, they seemed like random events," said John Foster,
associate director of the Massachusetts Institute of Technology's
Haystack Observatory. He is principal investigator of the Foundation
supported Millstone Hill Observatory, Wesford, Mass.
"People knew there was a space storm that must have disrupted their
system, but they had no idea why," said Tony Mannucci, group
supervisor of Ionospheric and Atmospheric Remote Sensing at NASA's
Jet Propulsion Laboratory, Pasadena, Calif. "Now we know it's not
just chaos; there is cause and effect. We are beginning to put
together the full picture, which will ultimately let us predict space
storms."
Predicting space weather is a primary goal of the National Space
Weather Program involving NASA, the foundation and several other
federal agencies. The view researchers created allowed them to link
movement of the plumes to processes that release plasma into space.
"Discovering this link is like discovering the movement of cold
fronts is responsible for sudden thunderstorms," said Jerry
Goldstein, principal scientist at the Southwest Research Institute,
San Antonio.
Since the occurrence of plasma plumes in the ionosphere disrupts GPS
signals, they provide a continuous monitor of these disturbances.
Researchers discovered a link between GPS data and satellite images
of the plasmasphere. The plasmasphere is a plasma cloud surrounding
Earth above the ionosphere. It is being observed from NASA's Imager
for Magnetopause to Aurora Global Exploration satellite. The
researchers discovered the motion of the ionospheric plumes
corresponded to the ejection of plasma from the plasmasphere during
space storms.
The combined observations allowed construction of an underlying
picture of the processes during space storms, when the Earth's
magnetic field is buffeted by hot plasma from the sun. As the solar
plasma blows by, it generates an electric field that is transmitted
to the plasmasphere and ionosphere. This electric field propels the
ionospheric and the plasmaspheric plasma out into space. For the
first time, scientists can directly connect the plasma observed in
the ionosphere with the plasmasphere plumes that extend many thousand
of kilometers into space.
"We also know these disturbances occur most often between noon and
dusk, and between mid to high latitudes, due to the global structure
of the electric and magnetic fields during space storms," said Anthea
Coster of the Haystack Observatory. "Ground and space based, and in
situ measurements are allowing scientists to understand the
ionosphere-thermosphere-magnetosphere as a coupled system."
The plumes degrade GPS signals in two primary ways. First, they cause
position error by time delaying the propagation of GPS signals.
Second, the turbulence they generate causes receivers to lose the
signal through an effect known as scintillation. It is similar to the
apparent twinkling of stars caused by atmospheric turbulence.
Researchers are presenting the findings today during the American
Geophysical Union meeting in San Francisco, Calif. For information
about space weather and other research on the Web, visit:
http://www.nasa.gov/vision/universe/solarsystem/cold_front.html For
information about NASA and agency programs on the Web, visit:
http://www.nasa.gov/home
-end-
--
--------------
Jacques :-)
www.spacepatches.info