Physics Department Seminar | University of Alaska Fairbanks |
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J O U R N A L C L U B |
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Subauroral
polarization streams (SAPS): Intrinsic response of geospace
during storm time |
by |
Dong Lin |
National Center for Atmospheric Research/High Altitude Observatory |
ABSTRACT Subauroral polarization streams (SAPS)
typically refer to an enhanced westward plasma flow channel in the
duskside subauroral ionosphere. SAPS overlap with the low-latitude
part of downward Region-2 field-aligned currents (FACs). The
relatively low subauroral conductance in this region requires a
strong electric field for current closure, which drives the fast
sunward plasma flow. Observations have shown dynamic variability
of SAPS under various solar wind and interplanetary magnetic field
(IMF) conditions, which are related to the variability of FACs and
auroral precipitation, as well as their source regions in the ring
current and plasmasheet. In this study, we use satellite
observations and numerical simulations with the state-of-the-art
Multiscale Atmosphere Geospace Environment (MAGE) model to
investigate: 1) The role of diffuse electron precipitation in the
formation of SAPS; and 2) Dawnside (as opposed to the more
conventional duskside) SAPS as a unique feature of major
geomagnetic storms. With data-model comparison, we will
demonstrate that SAPS result from the different behaviors of ring
current ions and plasma sheet electrons, and the corresponding
self-consistent response of the ionosphere-thermosphere system via
electrodynamic and particle coupling with the magnetosphere. We
conclude that SAPS distribution and variability represent a
fundamental feature of the geospace response to solar disturbances
during storm time. |
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Friday, 02 December 2022 |
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Only on Zoom : https://zoom.us/j/796501820?pwd=R2xEcXNwZGVRbG0va29iN2REU241UT09 | |||
3:45PM |