70 Years of Magnetospheric Modeling

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70 Years of Magnetospheric Modeling A
Tutorial George SiscoeCenter for Space
PhysicsBoston University
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Preliminaries

• Historical Approach
• Five Model Uses
• 1. Models that Represent
• Empirical and AI
• 2. Models that Explain
• Modular
• 3. Models that Reveal
• Kinetic and MHD
• 4. Models that Interpret
• All Types
• 5. Models that Predict
• All Types
• This Talk Considers only Modular and MHD
  Models that Explain and Reveal

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Outline

• Three Approaches
• 1. Modular
• 2. Regional MHD
• 3. Global MHD
• Future Directions

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Early 60s Culmination of the C-F project
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Mid 60s Discovery of the tail and the
magnetosheath
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• Summary of Chapman-Ferraro Epoch
• Well posed, fully explicit formulation
• Analytic solutions possible
• Size shape of the magnetopause found
• Dependence on S/W ram pressure found
• Dependence on dipole tilt found
• Global force balance understood
• But downhill from here
• No storms
• Empty tail
• No magnetosheath

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Modular Magnetosheath Spreiter Co.
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• Modules for the closed tail
• Current specification
• C-F approach
• Prescribed magnetopause
• Analytic tail approximation
• Convection added

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Modular Current Specification
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Analytic tail approximationsand convectionThe
Birn-Schindler project
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• Summary of Closed-Tail Epoch
• Ill posed but fully explicit formulations
• Results depend on assumptions and approach
• Analytic solutions still possible but
  superceded by computational solutions
• Global force balance understood
• Magnetotail B-field modeled
• In particular, Bz dependence on x modeled
• Dipole tilt geometry modeled
• Polar cap geometry and tilt dependence
  modeled
• Role of field-aligned currents discovered
• Convection ? time dependence discovered
• Modules for open tail models developed
• Initial state for regional MHD model developed
• But still no solar wind coupling
• No convection electric field

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• Modules for the Open Magnetosphere
• The Stern-singularity problem
• The Toffoletto-Hill solution
• Region 1 current modeling
• The SSM (Peroomian) extension

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Region 1 Currents SSM (P)
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• Summary of Open-Tail Epoch
• Ill posed but fully explicit formulations
• Results depend on assumptions and approach
• Analytic solutions still possible but
  superceded by computational solutions
• Magnetotail B-field modeled
• Polar cap potential modeled
• Stern singularity overcome in TH not in SSM
• Region 1 currents in SSM not in TH
• No plasma
• No physics for field-aligned currents

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Magnetosphere-Ionosphere Coupling Modules
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Rice Convection Model (RCM) The Wolf Co.
project
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RCM UCLA MHD Code (Toffoletto 2000)
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Equilibrium RCM Toffoletto 2000
Summary of MI Coupling Epoch

• Well posed fully explicit

• Analytic solutions possiblesuperceded by
  computations

• Assumed potential and plasma at boundaries

• Inner magnetosphereplasma modeled

• Physical region 2 currents

• No region 1 currents

• First RCM-MHD results

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Plasmoid Kelvin-Helmholtz wave Flux transfer event
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Plasmoid Simulation Lee et al. 1985
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Kelvin-Helmholtz Simulation Otto Fairfield
2000
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FTE Simulation Scholer 1989
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• Open geometry
• Magnetospheric sash
• E-Parallel reconnection

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Open Geometry
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Magnetospheric Sash
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E-Parallel Reconnection
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Future Directions
Hybrids
Other Magnetospheres
Deep Questions
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Acknowledgements
Bill White Keith Siebert Dan Weimer
Bengt Sonnerup Nelson Maynard Gary Erickson
NSF
NASA
DTRA