Determining the loss of outer radiation belt electrons: a high priority of LWS/RBSP
ROSES ID: NNH08ZDA001N Selection Year: 2009
Program Element: Independent Investigation
Principal Investigator: Xinlin Li
Affiliation(s): University of Colorado at Boulder
Project Member(s):
Selesnick, Richard S Collaborator AFRL/RVBXR
Looper, Mark Collaborator The Aerospace Corporation
Summary:
Energetic electrons in the magnetosphere have been observed to exhibit
high variation in flux during geomagnetic storms. The electron flux
enhancements are known to be due to acceleration processes within the
Earth's magnetosphere, while the largest loss due to precipitation into
the atmosphere also occurs during magnetic storms. Thus the acceleration
mechanisms that replenish radiation belt electrons during storms
must be even more effective than they appear since they act in the
face of this enhanced loss. Without a quantitative knowledge of the loss,
a quantitative knowledge of the acceleration mechanisms cannot be obtained.
A high priority of the NASA/LWS/Radiation Belt Storm Probe program is to
differentiate among competing processes affecting the precipitation and
loss of radiation belt electrons.
We propose to investigate and quantify the loss rate of radiation
belt electrons due to precipitation. We will accomplish this by analyzing
SAMPEX data over a solar cycle. SAMPEX circles the Earth 15 times each day
in a high inclination orbit and has been providing the measurements of
radiation belt electrons at different since its launch in 1992. Because
of its low altitude and large geometric factors and the fast time
resolution of its detectors, SAMPEX data are ideally suited for determining
losses of electrons to the atmosphere. A simple Loss Index Method to
calculate the loss rate will be applied to a variety of storm events and over
different phases of solar cycle to quantify the electron loss rate as a
function of radial distance, magnetic local time, electron energy and relevant
geomagnetic indices. We will also adopt the Drift-Diffusion Model that includes
the effects of azimuthal drifts and pitch angle diffusion. The detailed
Drift-Diffusion Model method will be used to validate the loss rate results
from the Loss Index Method. And we will also apply the Drift-Diffusion Model
method to obtain complete information about the pitch angle diffusion rate
as functions of energy and pitch angle during indvidual storms.
The proposed research has the direct impact to the LWS goals
and is closely related to LWS/RBSP mission. RBSP measurements will be
taken near the equatorial plane and because of the limited angular
resolutions, the pitch angle distribution near and inside the loss
cone is difficult to be resolved. SAMPEX still has the best data to
address the precipitation loss. Our proposed study will help the mission
to ensure full science closure by having a better understanding of the
precipitation loss.
Publications:
| Performance Year | Reference | Investigation Type | Actions |
|---|
| 1 | Tu, Weichao; Selesnick, Richard; Li, Xinlin; Looper, ...
| not set
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| 1 | Zhao, H.; Li, X.; (2013), Inward shift of outer radiatio...
| not set
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Presentations:
| Performance Year | Reference | Actions |
|---|
| 1 | Tu, W.; Selesnick, R. S.; Li, X.; Looper, M. D.; (2...
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| 1 | Tu, W.; Li, X.; Selesnick, R. S.; Looper, M. D.; (2...
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| 1 | Blum, L. W.; Li, X.; (2012), Rapid Enhanced Precipitatio...
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| 1 | Tu, W.; Reeves, G. D.; Cunningham, G.; Selesnick, R....
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| 1 | Zhao, H.; Li, X.; (2012), Inward shift of outer radiatio...
| |
| 1 | Blum, L. W.; Li, X.; (2013), Rapid enhanced precipitatio...
| |
| 1 | Blum, L. W.; Schiller, Q.; Li, X.; Millan, R. M.; ...
| |
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