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70 Years of Magnetospheric Modeling A Tutorial

70 Years of Magnetospheric Modeling A Tutorial George Siscoe Center for Space Physics Boston University. Preliminaries. Historical Approach Five Model Uses 1. Models that Represent Empirical and AI 2 . Models that Explain Modular 3. Models that Reveal

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70 Years of Magnetospheric Modeling A Tutorial

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  1. 70 Years of Magnetospheric Modeling A Tutorial George SiscoeCenter for Space PhysicsBoston University

  2. 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

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

  4. Modular 1930s: Inception of Chapman-Ferraro model

  5. Midgley and Davis 1963 Midgley and Davis 1963 Mead 1964 Early ‘60s: Culmination of the C-F project

  6. Midgley and Davis 1963 Mead 1964 Ness 1965 Fairfield 1968 Mid ‘60s: Discovery of the tail and the magnetosheath

  7. 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

  8. Luhmann et al., 1984 Modular Magnetosheath: Spreiter & Co.

  9. Modules for the closed tail: • Current specification • C-F approach • Prescribed magnetopause • Analytic tail approximation • Convection added

  10. Mead and Williams 1965 Olson and Pfitzer 1974 Bird 1979 Modular Current Specification

  11. Unti and Atkinson 1968 Siscoe 1966 Chapman-Ferraro approach to modeling the closed tail Spreiter and Alksne 1969

  12. Prescribed magnetopause approach to modeling the closed tail Schulz source surface model Voigt stretch model Schulz source surface model

  13. Analytic tail approximationsand convection:The Birn-Schindler project

  14. 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but fully explicit formulations • Results depend on assumptions and approach • Analytic solutions still possible but superceded by computational solutions • Global force balance understood • Magnetotail B-field modeled • In particular, Bz dependence on x modeled • Dipole tilt geometry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

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

  16. The Stern-singularity problem E parallel Siscoe 1988

  17. T-H T-H and SSM compared SSM (P)

  18. Peroomian et al. 1991 Siscoe et al. 1991 Region 1 Currents: SSM (P)

  19. 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

  20. Jaggi & Wolf 1973 Vasyliunas 1970 Magnetosphere-Ionosphere Coupling Modules

  21. RCM Master Plan Rice Convection Model (RCM) The Wolf & Co. project

  22. RCM + UCLA MHD Code (Toffoletto 2000)

  23. 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

  24. Regional MHD Plasmoid Kelvin-Helmholtz wave Flux transfer event

  25. Plasmoid Simulation Lee et al. 1985

  26. Kelvin-Helmholtz Simulation Otto & Fairfield 2000

  27. FTE Simulation Scholer 1989

  28. Global MHD • Open geometry • Magnetospheric sash • E-Parallel & reconnection

  29. Raeder GGCM Web Site Open Geometry

  30. -10 -5 -2 0 -1 2 -10 IMF 4 1 IMF -5 3 + 5 X=6 + + X=7 + -10 -5 + 0 2 4 6 X=8 IMF Magnetospheric Sash

  31. E-Parallel & Reconnection

  32. Future Directions Hybrids Other Magnetospheres Deep Questions

  33. Acknowledgements Bill White Keith Siebert Dan Weimer Bengt Sonnerup Nelson Maynard Gary Erickson NSF NASA DTRA

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