Bill Lotko

1
Ionospheric Outflow
Bill Lotko David Murr1 John Lyon1,2,3 Mike
Wiltberger2 John Gagne1 Paul Melanson1
1 2
3
Contributions
2
Ring Current and Plasma Sheet Composition
Nosé et al. 2005
3
O Plasmasheet

• Plasmasheet
• Normally H dominant
• O-rich during storms
• O injections from
• Cusp fountain
• Nightside BPS
• Stormtime substorms
• H is swept away
• Leaving O dominant
• pressure and density
• Earthward injected O
• dominates ring current

Kistler et al. 2005
4
Include also Borovsky 2006 figure
Reconnection Rate
Shay and Swisdak, 2004

• Density fraction nh 0.39 ne
• Heavy ions reduce reconnection rate by 50

5
Radiation Belt Energization and Loss

• Wave emissions depend
• on plasma conditions
• cold plasma density
• mass composition

sun
(loss)
(energization and loss)
6
Kelvin-Helmholtz Instability
boundary layer transport
Bouhram et al. 2005
Instability criterion
7
Cross-Polar Cap Potential
inertial loading
1998
Winglee et al. 2002
8
Outflow Physics guiding center
equations
9
Polar Wind
Hydrostatic Equilibrium
e-
O
10
Polar Wind
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Transverse acceleration ? mirror force
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Cusp Outflow
Enhanced ionization Joule Heat Electron
precipitation Alfvénic Poynting flux
?
O outflow
30º Lat
cf. Strangeway et al. 05
Zheng et al. 05
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CuspHeating Wall
Knudsen et al. 1994
Ion Fountain
14
Causal Relations
1
2
Strangeway et al. 05
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Causal Relations
1
2
3
Strangeway et al. 05
16
1945 UT
30º Lat
20 Nov 2003
Foster et al. 05
17
Magnetospheric dynamo (? geomagnetically fixed)
Convective plasma surge ? Outflow surge
Sondrestrom ISR
11 Feb 2002
Semeter et al. 03
Semeter et al. 03
18
Chaston et al. 03
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Outflow across the auroral oval
Paschmann et al. 2003
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DC EM Flux
AC EM Flux
Sdc
Sac
mW/m2
mW/m2
Energy In
Olsson et al. 04
Keiling et al. 03
Astrid-2 / 1000 km
Polar / 4-6 RE
O Velocity
O Up Flux
ions/m2-s
km/s
Ions Out
Abe et al. 04
Lennartsson et al. 04
Akebono / 1500-8500 km
Polar / 7600 km
21
LFM Global MHD Model
equations
22
Ionospheric Potential
23
LFM Grid
Y (RE)
53x48x64
0
X (RE)
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Ionospheric Grid
gt 200 km grid resolution (typical)
? Small-scale Alfvén waves are not
resolved
25
Empirical Model for Ionospheric Outflow
FAST data near 4000-km altitude in the
low-altitude cusp
Strangeway et al. 05 Zheng et al. 05
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Auroral/Cusp Outflow
Run 1 ? 1.0 Run 2 ? 0.1
OUTFLOW ALGORITHM
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Event Simulation (CISM Long Run)
IMF / SW at 20 RE
Bx ? 0
By lt 0
Bz variable
vx ? 375 km/s
PDYN ? steady until 0430
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Fluence comparisons Runs 1 and 2
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H outflux at 2.25 RE Run 1
N
S
DUSK
DUSK
Bz, nT
UT
4 Mar 96
10 min shift
30
UT
4 Mar 96
31
Average Number Flux
8.5 simulation hours
Oct 97 Mar 98
North
South
Polar perigee
DAWN
DUSK
Log (Flux, / m2-s)
Log (Flux, / m2-s)
9
10
11
12
13
9
10
11
12
2 ? 1025 ions/s
3 ? 1025 ions/s
2-3 ? 1024 ions/s
FLUENCE
Lennartsson et al. 04
32
MI Coupling Diagnostics

• Plasma addition at inner boundary ?

• Higher density
• Lower ? (and ?e)
• Less e- energy flux
• Lower ?
• Less FAC
• Higher ?PC

• More modest ? in Joule dissipation

33
Cross-Polar Cap Potential constant conductance
Winglee et al. 2002
Winglee et al. 02
34
LFM Precipitation Algorithm
35
Feedback Outflow with Precipitation
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Feedback Outflow w/o Precipitation
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Model extensions
38
Conclusions

• Largest outflows when IMF BZ lt 0 and variable
• Mass persistence in inner magnetosphere less in
  outer regions
• H outflow increases ?PC while reducing I
• Comparatively modest impact on Joule dissipation
• FEEDBACK between outflow-induced density
  enhancements and electron precipitation,
  conductivity dynamics

39
Magnetopause Boundary Layer Density
Probability Density vs ?o/?H Cluster
Bouhram et al. 2005
Bouhram et al. 05
40

• Observational Statistics
• (Yau and André 97 Cully et al. 03 Lennartsson
  et al. 04)
• Outflow fluence increases
• at higher altitude
• for southward IMF
• with greater SW PDYN
• Outflow energy increases
• at higher altitude
• with greater SW PDYN
• 1-100 GW / hemisphere required to power the H
  outflow
• Polar ions 15 eV 33 keV

41
AC Poynting Flux (and the effect of ??)

• Morphology
• Amplitude
• Phase

42
Sampling Statistics for Empirical Outflow
Relations
43
UT
4 Mar 96
44
Where does the ionospheric H go?
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Control Volume Analysis
Not to scale
46
Control Volume Analysis
Not to scale
47
Control Volume Analysis
Not to scale
48
Control Volume Analysis
Not to scale
49
Mass Addition Diagnostics

• Mostly the inner magnetosphere
• Little persistence in Lobe and PS
• Mass addition is regulated by
• IMF Bz
• IMF Variability
• Outflow latency is ? 20 minutes relative to IMF
  turnings