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Dynamics and Structure of SubAuroral
Polarization Streams
Evgeny Mishin
Boston College ISR
With contributions from & thanks to Bill Burke
MIT Haystack Observatory
November 7, 2005
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OUTLINE
•
Prompt SAPS response to the substorm onset
and solar wind oscillations: DMSP and ISR
•
SAPS-wave structures: The benchmark of RC
injections
•
Plasma waves and heating/acceleration in the
ring current- plasmasphere overlap
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Solar wind & IMF oscillations
[Mishin et al., 2002]
Sept 25, 1998
12-min oscillations
3
A stormtime substorm
21.0 MLT& 66 MLat
dipolarization
The substorm onset at 08:18 UT
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Response to the substorm onset
Before
Onset: 0818 UT
SAPS
after
21.0 MLT & L~6
SAPS: 0830 UT
15.5 MLT & L~3
SAPS
15.5 MLT
ÙL~3
&ÙMLT~5.5
in 12 min
VR~ 30 km/s
Vϕ~ 15 km/s
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Solar wind- & IMF-driven
SAPS- modulation
~12-min
oscillations
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Structured SAPS
Nov 6, 2001
Onset at ~0350 UT
PS equatorial boundary
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Strong SAPSWS:
The benchmark of RC injections
DMSP F14, April 6, 2000
electrons
[Mishin et al., 2004]
RC ions
ions
“Strong”
oscillations ≥ mean
SAPSWS:
Meso-scale
Alfven wave
Electron temperature
Ion temperature
Density
troughs
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RC-injection events: Waves
[Mishin & Burke, 2005]
CRRES & DMSP, June 5, 1991
UHR
LHR
inner edge
Plasma Sheet boundary
Electrons
Ions
NOSE
SAPSWS
Suprathermal
electrons &
ions
Density trough
Alfven
wavestructure
SAPSWS maps to
the wave structure
observed by
CRRES at 17 MLT
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Alfve’n waves in RC- plasmasphere overlap:
Current-convective instability
ω ' = ω − k|| gJ || /(ene )
[Volkov& Maltsev, 1986]
(Static approximation)
Transverse motion of
RC cloud favors
generation of
short-scale modes
ω ' = ω − k|| gJ || /(ene ) − k⊥ gU D
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SAPSWS evolution after substorm injections
June 5, 1991 [Mishin and Burke, 2005]
electr
ons
ions
Density
troughs
substorm onsets
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Electron Heating
Wanted
Heating source of plasmaspheric electrons at
the RC’s inner edge
Collisional
heating rate
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Diamagnetic current LH instability
diamagnetic current
LaBelle& Treumann [1988]
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Plasma heating/acceleration: LH collapse
LH collapse threshold
near RC’s inner edge
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SUMMARY (“RC/SAPS”)
•Substorm injections quickly affect already existing SAPS.
•SAPS wave-structures (SAPSWS) follow injections of RC particles
and are generated by the current-convective instability at the forefront.
•Precipitating ion & electron fluxes, elevated electron temperatures,
and highly-structured density troughs accompany the SAPSWS.
•The energy source for the electron heating/acceleration equatorward
of the SAPSWS is likely the LH turbulence driven by the diamagnetic
current at the RC inner edge.
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Trough & elevated Te
troug
h
troug
h
Foster et al [1994]
Elevated Te is due to heat
transport from the plasmasphere
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Plasmaspheric plasma heating/acceleration
near the RC’s inner edge
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Elevated Te and density troughs
Topside
ionosphere
Charge Transfer
Hot electrons pump N2
vibrational levels.
recombination of NO+
leads to plasma depletion.
105
Trough depth
CT rate coefficient
O + + N 2 (V ) → N O + + N * increases, and fast
400 km
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Density trough
Scenario of the high-Te
related density trough
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