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![Page 1: Ring Current and Plasmasphere Accomplishments During the GEM IM/S Campaign Mike Liemohn GEM Workshop Tutorial June 27, 2006.](https://reader035.fdocuments.in/reader035/viewer/2022081506/56649d495503460f94a26302/html5/thumbnails/1.jpg)
Ring Current and Plasmasphere Accomplishments During the GEM IM/S Campaign
Mike Liemohn
GEM Workshop Tutorial
June 27, 2006
![Page 2: Ring Current and Plasmasphere Accomplishments During the GEM IM/S Campaign Mike Liemohn GEM Workshop Tutorial June 27, 2006.](https://reader035.fdocuments.in/reader035/viewer/2022081506/56649d495503460f94a26302/html5/thumbnails/2.jpg)
IM/S Campaign: Outcomes and Questions
• How well do we understand the physics of the inner magnetosphere? – What are the physical questions remaining to understand the inner
magnetosphere?– How far have we come since the beginning of the IM/S Campaign (1998)?
• What advances in observations are needed next? – Of these, which can be anticipated in current plans? – Which observations can be readily achieved, which are dependent on
advances in experimental physics, and which cannot be currently foreseen as possible?
• What advances in modeling are needed next? – Are there important physical processes that are not yet included? – Can regional models be advanced independent of system-wide modeling? – What advances in numerical technique and processing power are needed?
![Page 3: Ring Current and Plasmasphere Accomplishments During the GEM IM/S Campaign Mike Liemohn GEM Workshop Tutorial June 27, 2006.](https://reader035.fdocuments.in/reader035/viewer/2022081506/56649d495503460f94a26302/html5/thumbnails/3.jpg)
Basic Definition: Plasmasphere
• Cold: Less than 1 eV, maybe up to 10 eV• Dense: 100s-1000s cm-3, lower out near geos.• Ionospheric: source is the subauroral ionosphere• Mostly Protons: oft-quoted composition, 77% H+,
20% He+, and 3% O+
• E-field dominated: spatial extent governed by magnetospheric electric field time history
• Important: dominates the mass density of the inner magnetosphere
![Page 4: Ring Current and Plasmasphere Accomplishments During the GEM IM/S Campaign Mike Liemohn GEM Workshop Tutorial June 27, 2006.](https://reader035.fdocuments.in/reader035/viewer/2022081506/56649d495503460f94a26302/html5/thumbnails/4.jpg)
Basic Definition: Ring Current• Hot: 1-400 keV• Tenuous: quiet, 1 cm-3; active, 10s cm-3
• Plasma sheet: source is near-Earth magnetotail, wherever that comes from
• Mostly Protons: During big storms, O+ can dominate
• Complicated Drift: E-field, B-field, Gradient-curvature terms
• Important: Dominates the energy density of the inner magnetosphere
![Page 5: Ring Current and Plasmasphere Accomplishments During the GEM IM/S Campaign Mike Liemohn GEM Workshop Tutorial June 27, 2006.](https://reader035.fdocuments.in/reader035/viewer/2022081506/56649d495503460f94a26302/html5/thumbnails/5.jpg)
Ring Current Advances
• Storm-Time Ring Current Morphology– Partial ring current dominance during storms
• Connection/Feedback with Electric Field– The ionosphere matters
• Connection/Feedback with Magnetic Field– The B-field really is tweaked by currents
• Connection/Feedback with Plasma Sheet– Has anyone seen my source term?
• Connection/Feedback with Plasma Waves– Collisionless energy transfer
![Page 6: Ring Current and Plasmasphere Accomplishments During the GEM IM/S Campaign Mike Liemohn GEM Workshop Tutorial June 27, 2006.](https://reader035.fdocuments.in/reader035/viewer/2022081506/56649d495503460f94a26302/html5/thumbnails/6.jpg)
Ring Current Morphology• The ring current is not a ring during storms
Liemohn et al., JGR, 2001
-60
-40
-20
0
20
40
0 06:00 12:00 18:00 24:00 UT
31 March 2001
From Don Mitchell
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Ring Current-FAC- Relationship• A pressure peak requires FACs at each end to
close the partial ring current, and the resulting potentials act to expel the pressure peak
Liemohn and Brandt,AGU Mon v. 159, 2005
![Page 8: Ring Current and Plasmasphere Accomplishments During the GEM IM/S Campaign Mike Liemohn GEM Workshop Tutorial June 27, 2006.](https://reader035.fdocuments.in/reader035/viewer/2022081506/56649d495503460f94a26302/html5/thumbnails/8.jpg)
Electric Field Connection• Partial ring current causes a potential well
near midnight, changing the hot ion drift paths in the inner magnetosphere
8 UT 12 August 2000
Post-midnight enhance-
ment
Fok et al., SSR, 2003
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Electric Field, Part 2: SAPS and Flow Channels
• SAPS: subauroral polarization stream– Enhanced outward E-field in dusk/evening sector
causing faster-than-normal sunward flow
• Flow channels: narrow regions of injection– Enhanced westward E-field in localized sector of
nightside causing fast injection
Foster and Vo, JGR, 2002Chen et al., JGR, 2003
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04x10298x1029
1.2x10301.6x1030
2x1030
-80
0
80
Dst observed, nT
1-300 keV
20-80 keV
1-30 keV
80-300 keV
04x10298x1029
1.2x10301.6x1030
2x1030
Ring current energy, keV
04x10298x1029
1.2x10301.6x1030
2x1030
dipole
dipole + T89
dipole + T01s
0 6 12 18 0 6 12 18 0 6 12 18 24 Apr 21 Apr 22 Apr 23 UT
Ganushkina et al., JGR, 2006
Magnetic Field Connection
• One-way connection: B-field influences on the ring current– Trends in the ring current
energy content time series are best reproduced when B is stretched realistically and when convective & inductive E-fields are included
Particle Tracing ModelWith Inductive-E Pulses
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Zaharia et al., JGR, 2005
Magnetic Fields: 2-Way Coupling• B-field found from RC result, then fed back to RC model• Pressure (P) overall significantly smaller (half) in self-consistent (SC)
case vs. dipole field; P|| (not shown) not as affected• Less plasma delivered close to Earth, but more structure• Less filled flux tubes are able to drift closer to Earth
![Page 12: Ring Current and Plasmasphere Accomplishments During the GEM IM/S Campaign Mike Liemohn GEM Workshop Tutorial June 27, 2006.](https://reader035.fdocuments.in/reader035/viewer/2022081506/56649d495503460f94a26302/html5/thumbnails/12.jpg)
The Flip Side of Feeback:Effect of the Hot Ions on B
• X-Y plane pressures with 3-d B lines for a given latitude overdrawn
• Tail stretching
– Pressure much higher near the Earth with kinetic code embedded
– Hot ions near Earth alter the field and plasma in other areas
With Kinetic CodeWithout Kinetic Code
From Toth, Ridley, and De Zeeuw
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Ebihara & Ejiri, JGR, 2000Liemohn and Ridley, JGR 2002
Plasma Sheet Connection• Plasma sheet density controls the strength
of the ring current
• Plasma sheet temperature also affects ring current intensity
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Plasma Wave Connection• Calculating the EMIC wave energy density self-consistently
with the hot ions allows for nonlinear feedback between them– Scattering of ions depends on Bw and – Preference for field-aligned
• Also a heat source for the thermal plasma
Khazanov et al., JGR, 2006
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What is Needed for Improvement• Major Modeling Needs:
– More fully develop self-consistency in the models– Continue to couple ring current models to other inner
magnetospheric models and to global models– Better electron ring current loss lifetimes/diffusion
coefficients– Algorithms for accurate hot plasma precipitation
calculation
• Major Observational Needs:– Routine ion composition measurements at GEO– More reliable electron ring current measurements– Multi-spacecraft particle, field, and wave measurements
in the ring current region– More/better ionospheric conductance measurements
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Plasmasphere Advances
• Global Morphology– The plasmapause is lumpy, and we know why
• Magnetic Field Effects– The plasmasphere is more than just an E-field
history integrator
• Plasmaspheric Refilling– Diffusive equilibrium is not quite right
• Mass Density– ULF wave analysis comes of age
![Page 17: Ring Current and Plasmasphere Accomplishments During the GEM IM/S Campaign Mike Liemohn GEM Workshop Tutorial June 27, 2006.](https://reader035.fdocuments.in/reader035/viewer/2022081506/56649d495503460f94a26302/html5/thumbnails/17.jpg)
Global Morphology
• IMAGE EUV has shown the plasmasphere to be a lumpy and bumpy creature– Tracer of the
time-history of inner mag. fields (mostly E, also B)
Sandel et al., SSR, 2003
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Plasmapause and the E-Field• Electric field choice can greatly influence
the shape and dynamics of the plasmapause
Liemohn et al., JGR, 2004
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Slide from Stan Sazykin, Rice U.
Plasmapause and The B-Field
• Comparison of the RCM-computed plasmapause boundary – Magnetic Field: HV95 (left panel) and T03S (right panel)
– Plasmasphere is orange, filled at start of simulation
– Contour lines: flow lines for cold (=0) particles
– EUV-extracted plasmapause: blue symbols in each plot
Hilmer-Voigt B-Field T03s B-Field
![Page 20: Ring Current and Plasmasphere Accomplishments During the GEM IM/S Campaign Mike Liemohn GEM Workshop Tutorial June 27, 2006.](https://reader035.fdocuments.in/reader035/viewer/2022081506/56649d495503460f94a26302/html5/thumbnails/20.jpg)
Plasmaspheric Refilling
• Variable refilling rates– Slow-then-fast refilling– Different processes– Lawrence et al., JGR, 1999
• Field-line distributions– Flat at the equator– Does not follow
diffusive equilibrium– Reinisch et al., JGR, 2004
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Plasmaspheric Mass Density
• Ground-based magnetometers and field-aligned wave propagation – Multiple stations can
be used to extract mass density along a field line
– These results: from the MEASURE mag chain
Berube et al., GRL, 2005
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Magnetoseismology• Probing the mass density of the magnetosphere via
plasma wave transit times
Chi and Russell, GRL, 2005
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What is Needed for Improvement• Major Modeling Needs:
– Inclusion of heavy ion species– Inclusion of temperature calculation– Better coupling with ring current and ionosphere– Inclusion in global models– Small-scale structure, subcorotation, and refilling still
not well understood
• Major Observational Needs:– Routine derivation of TEC from LEO– Refinement of ULF-wave data analysis techniques– Establish global ground and space operational systems
for making coordinated observations in time and space– Follow-on IMAGE-type suite of instruments
![Page 24: Ring Current and Plasmasphere Accomplishments During the GEM IM/S Campaign Mike Liemohn GEM Workshop Tutorial June 27, 2006.](https://reader035.fdocuments.in/reader035/viewer/2022081506/56649d495503460f94a26302/html5/thumbnails/24.jpg)
Ring Current Dynamics
Role of Plasma Sheet Source Population
Role of Driving E and B Fields
Role of Loss Mechanisms
Morphology of Storm
Quantification of Interdependencies?
![Page 25: Ring Current and Plasmasphere Accomplishments During the GEM IM/S Campaign Mike Liemohn GEM Workshop Tutorial June 27, 2006.](https://reader035.fdocuments.in/reader035/viewer/2022081506/56649d495503460f94a26302/html5/thumbnails/25.jpg)
Plasmasphere Dynamics
Subauroral Electric Fields on All Scales
Storm-time Sources: Composition & Latitude & Longitude
Losses Internal and External to Storm-Time Plasmapause
Morphology of Storm
Origin of Plasmaspheric Structures at all Scales?
![Page 26: Ring Current and Plasmasphere Accomplishments During the GEM IM/S Campaign Mike Liemohn GEM Workshop Tutorial June 27, 2006.](https://reader035.fdocuments.in/reader035/viewer/2022081506/56649d495503460f94a26302/html5/thumbnails/26.jpg)
Inner Magnetospheric Coupling:Ring Current and Plasmasphere
Ring Current
E and B Fields
Plasmasphere
Locali
zed
IM p
ertu
rb.
J , J ||
Heating
Localized IM perturb.
Conductivity
Collisions, WPI catalyst
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Inner Magnetospheric Coupling
Ring Current
LocalizedE and B FieldPertubations
Plasmasphere
Conductivity
Collisions, WPI catalyst
E and B
Heating
Radiation Belts
Pre
cip,
J, J
||
E a
nd
B
Diagnostic tracersPrecip
.
WPI catalyst
BD
iagn
ostic
trac
ers
Plas
ma
Wav
es, S
eed
Pop.
Ionospheric Conductance
and Dynamics
Ionospheric
OutflowPlasma Sheet
ULF Waves
Large Scale E and B Fields
Liemohn, JGR, 2006
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A Complicated Flow Chart
Liemohn and Khazanov, AGU Mon. 156, 2005
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Culmination of the IM/S Campaign
• The Inner Magnetosphere/Storms Assessment Challenge (the IMSAC)– The final hurrah of the IM/S Campaign– Focus the community's efforts on a common
goal– Choose a few specific events for intense study– Choose a few questions to direct the
investigations
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Purpose of the IMSAC
• Goal 1: To what accuracy can the current inner magnetospheric models predict the state of the fields and plasma? – Related question: What level of model
sophistication is needed to get a certain level of accuracy in the result?
• Goal 2: What is the present consensus understanding of inner magnetospheric physics?– Related question: What is the full set of physics
for a complete description?
![Page 31: Ring Current and Plasmasphere Accomplishments During the GEM IM/S Campaign Mike Liemohn GEM Workshop Tutorial June 27, 2006.](https://reader035.fdocuments.in/reader035/viewer/2022081506/56649d495503460f94a26302/html5/thumbnails/31.jpg)
Storm Selection
• Two storms for the plasmasphere and ring current:– April 22, 2001: cloud with southward IMF– October 21-23, 2001: sheath/cloud combo
• Two storms for the radiation belts:– October 21-23, 2001: large storm followed by a
large RB enhancement– September 4-9, 2002: a series of storms with
interestnig RB dynamics
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Culmination of the IMSAC
• JGR-Space Special Section– Submission deadline was January 9th– 17 manuscripts submitted
• Some in print/press, most still in review/revision
• Over half focused on ring current dynamics
• Please, keep submitting papers– Additional papers can still be linked to the
special section in the online listing
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Conclusions
• GEM IM/S Campaign was a success!– Focused community effort on plasmasphere and ring
current issues
– Understanding of magnetic storms is much better now
– New questions are plentiful
• Still to do– Coupling processes between plasma populations
– Self-consistent simulations still need improvement
– Coupling to sub-auroral ionosphere
– Coupling to outer magnetosphere
– Understanding small-scale plasma/field structures