May 27th 05, 08:26 PM
http://www.ucar.edu/news/releases/2005/gibson.shtml
Contacts for This Release
For Journalists
Anatta ), head of Media Relations, 303-497-8604
Sarah Gibson ), NCAR High Altitude Observatory,
303-497-1587
UCAR Communications
General inquiries
Yvonne Mondragon ),
303-497-8601
Head of Visual Services
Nita Razo ), 303-497-8606
NCAR Research Sheds Light on Solar Storms
May 26, 2005
BOULDER - New research from the National Center for Atmospheric
Research
(NCAR) links a particular magnetic structure on the Sun with the
genesis
of powerful solar storms that can buffet Earth's atmosphere. The
research may enable scientists to create more accurate computer models
of the solar storms, known as coronal mass ejections (CMEs), and could
eventually point the way to forecasting the storms days before they
occur.
Sarah Gibson, a scientist at NCAR's High Altitude Observatory (HAO),
will present her findings at the American Geophysical Union conference
in New Orleans on Thursday, May 26. Her invited talk is in recognition
of winning this year's Karen Harvey Prize. The award, by the Solar
Physics Division of the American Astronomical Society, recognizes an
early-career scientist who has produced exceptional solar research.
CMEs are a focus of solar research because they suddenly and violently
release billions of tons of matter and charged particles that escape
from the Sun and speed through space. Those ejections that are pointed
toward Earth can set off disturbances when they reach the upper
atmosphere, affecting satellites, ground-based communications systems,
and power grids.
Sarah Gibson
Sarah Gibson struck a pose for the camera as she gazed at her first
solar eclipse in 1991. Behind her on the far left is NCAR's Mauna Loa
Solar Observatory, the home of state-of-the-art coronameters to capture
detailed images of the Sun's outermost region.
For her research, Gibson turned to a unique dataset: white-light images
of the lower reaches of the Sun's enormous halo, called the corona.
Taken by HAO's Mark-IV K-Coronameter on Mauna Loa in Hawaii, the images
are sensitive to density alone, avoiding the ambiguity of most other
solar images that depend on both temperature and density. The Mark-IV
images revealed that lower-density regions in the corona consistent
with
twisted magnetic field lines can form prior to a CME. The twisted
areas,
known as magnetic flux ropes, store massive amounts of energy.
"The structures indicate a magnetic system that has enough energy to
fuel a CME," Gibson explains. "But their presence is not, by itself, an
indication that a CME is about to occur. For that, we need to look at
additional characteristics."
The research may put to rest an important debate among solar physicists
over whether magnetic flux ropes can form prior to an ejection or are
merely present when an ejection takes place. Gibson's findings suggest
that, to understand the forces that create CMEs, solar scientists
should
use magnetic flux ropes as the starting point of computer models of the
massive storms.
To conduct her study, Gibson used images from the Mark-IV K-Coronameter
to observe dark, lower-density areas, known as cavities, that can be
formed by the strong, sheared magnetic fields of magnetic flux ropes.
Gibson, along with HAO collaborators David Foster and Joan Burkepile,
analyzed 13 cavity systems from November 1999 to January 2004. Seven of
these systems could be associated with CMEs, and four cavities were
directly observed by the Mark-IV telescope to erupt as CMEs. Gibson
used
a second technique to identify an additional eight CMEs for analysis
that were observed by Mark-IV to erupt from already-formed cavities.
She
found those cases by gathering images of CMEs and backtracking to see
whether cavities existed at those CME sites before each eruption.
One of Gibson's next steps will be to analyze cavities that result in
CMEs to determine whether they have identifiable characteristics that
may help scientists forecast a CME. Her preliminary findings indicate
that a cavity begins to bulge and rise higher in the corona just before
erupting. Cavities may also darken and become more sharply defined
prior
to eruption.
Solar images
These images, taken by NCAR's Mark-IV K-Coronameter on Mauna Loa in
Hawaii, capture features in the Sun's corona (blue area). The black
disk
in the middle obscures the Sun itself. The image on the right, taken on
July 22, 2002, shows a cavity in the corona (indicated by arrow). The
image on the left, from November 19, 1999, shows a coronal mass
ejection
(indicated by arrow) that has erupted from a cavity. Watch an animation
of the November 19 coronal mass ejection
<http://web.hao.ucar.edu/%7Esgibson/CAVITY/19991119/19991119.mk4.mov>.
Gibson will also try to determine how widespread cavities are, and if
it
is possible that most, or even all, CMEs are preceded by the formation
of magnetic flux ropes. Beginning next year, she will supplement the
Mauna Loa observations with data from a pair of new NASA satellites,
known as STEREO (Solar Terrestrial Relations Observatory). Instruments
aboard STEREO will provide stereoscopic measurements and 24-hour
coverage of the lower solar corona, significantly increasing the
chances
of directly observing cavities erupting into CMEs.
------------------------------------------------------------------------
The National Center for Atmospheric Research and UCAR Office of
Programs
are operated by UCAR under the sponsorship of the National Science
Foundation and other agencies. Opinions, findings, conclusions, or
recommendations expressed in this publication do not necessarily
reflect
the views of any of UCAR's sponsors.
Contacts for This Release
For Journalists
Anatta ), head of Media Relations, 303-497-8604
Sarah Gibson ), NCAR High Altitude Observatory,
303-497-1587
UCAR Communications
General inquiries
Yvonne Mondragon ),
303-497-8601
Head of Visual Services
Nita Razo ), 303-497-8606
NCAR Research Sheds Light on Solar Storms
May 26, 2005
BOULDER - New research from the National Center for Atmospheric
Research
(NCAR) links a particular magnetic structure on the Sun with the
genesis
of powerful solar storms that can buffet Earth's atmosphere. The
research may enable scientists to create more accurate computer models
of the solar storms, known as coronal mass ejections (CMEs), and could
eventually point the way to forecasting the storms days before they
occur.
Sarah Gibson, a scientist at NCAR's High Altitude Observatory (HAO),
will present her findings at the American Geophysical Union conference
in New Orleans on Thursday, May 26. Her invited talk is in recognition
of winning this year's Karen Harvey Prize. The award, by the Solar
Physics Division of the American Astronomical Society, recognizes an
early-career scientist who has produced exceptional solar research.
CMEs are a focus of solar research because they suddenly and violently
release billions of tons of matter and charged particles that escape
from the Sun and speed through space. Those ejections that are pointed
toward Earth can set off disturbances when they reach the upper
atmosphere, affecting satellites, ground-based communications systems,
and power grids.
Sarah Gibson
Sarah Gibson struck a pose for the camera as she gazed at her first
solar eclipse in 1991. Behind her on the far left is NCAR's Mauna Loa
Solar Observatory, the home of state-of-the-art coronameters to capture
detailed images of the Sun's outermost region.
For her research, Gibson turned to a unique dataset: white-light images
of the lower reaches of the Sun's enormous halo, called the corona.
Taken by HAO's Mark-IV K-Coronameter on Mauna Loa in Hawaii, the images
are sensitive to density alone, avoiding the ambiguity of most other
solar images that depend on both temperature and density. The Mark-IV
images revealed that lower-density regions in the corona consistent
with
twisted magnetic field lines can form prior to a CME. The twisted
areas,
known as magnetic flux ropes, store massive amounts of energy.
"The structures indicate a magnetic system that has enough energy to
fuel a CME," Gibson explains. "But their presence is not, by itself, an
indication that a CME is about to occur. For that, we need to look at
additional characteristics."
The research may put to rest an important debate among solar physicists
over whether magnetic flux ropes can form prior to an ejection or are
merely present when an ejection takes place. Gibson's findings suggest
that, to understand the forces that create CMEs, solar scientists
should
use magnetic flux ropes as the starting point of computer models of the
massive storms.
To conduct her study, Gibson used images from the Mark-IV K-Coronameter
to observe dark, lower-density areas, known as cavities, that can be
formed by the strong, sheared magnetic fields of magnetic flux ropes.
Gibson, along with HAO collaborators David Foster and Joan Burkepile,
analyzed 13 cavity systems from November 1999 to January 2004. Seven of
these systems could be associated with CMEs, and four cavities were
directly observed by the Mark-IV telescope to erupt as CMEs. Gibson
used
a second technique to identify an additional eight CMEs for analysis
that were observed by Mark-IV to erupt from already-formed cavities.
She
found those cases by gathering images of CMEs and backtracking to see
whether cavities existed at those CME sites before each eruption.
One of Gibson's next steps will be to analyze cavities that result in
CMEs to determine whether they have identifiable characteristics that
may help scientists forecast a CME. Her preliminary findings indicate
that a cavity begins to bulge and rise higher in the corona just before
erupting. Cavities may also darken and become more sharply defined
prior
to eruption.
Solar images
These images, taken by NCAR's Mark-IV K-Coronameter on Mauna Loa in
Hawaii, capture features in the Sun's corona (blue area). The black
disk
in the middle obscures the Sun itself. The image on the right, taken on
July 22, 2002, shows a cavity in the corona (indicated by arrow). The
image on the left, from November 19, 1999, shows a coronal mass
ejection
(indicated by arrow) that has erupted from a cavity. Watch an animation
of the November 19 coronal mass ejection
<http://web.hao.ucar.edu/%7Esgibson/CAVITY/19991119/19991119.mk4.mov>.
Gibson will also try to determine how widespread cavities are, and if
it
is possible that most, or even all, CMEs are preceded by the formation
of magnetic flux ropes. Beginning next year, she will supplement the
Mauna Loa observations with data from a pair of new NASA satellites,
known as STEREO (Solar Terrestrial Relations Observatory). Instruments
aboard STEREO will provide stereoscopic measurements and 24-hour
coverage of the lower solar corona, significantly increasing the
chances
of directly observing cavities erupting into CMEs.
------------------------------------------------------------------------
The National Center for Atmospheric Research and UCAR Office of
Programs
are operated by UCAR under the sponsorship of the National Science
Foundation and other agencies. Opinions, findings, conclusions, or
recommendations expressed in this publication do not necessarily
reflect
the views of any of UCAR's sponsors.