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
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
Outline
•Three Approaches
1. Modular
2. Regional MHD
3. Global MHD
• Future Directions
Modular
1930s: Inception of Chapman-Ferraro model
Midgley
and Davis
1963
Mead
1964
Early ‘60s: Culmination
of the C-F project
Midgley
and Davis
1963
Mead
1964
Mid ‘60s: Discovery of the tail
and the magnetosheath
Midgley
and Davis
1963
Ness
1965
Fairfield
1968
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
Modular Magnetosheath:
Spreiter & Co.
Luhmann
et al., 1984
Modules for the closed tail:
• Current specification
• C-F approach
• Prescribed magnetopause
• Analytic tail approximation
• Convection added
Modular Current
Specification
Olson and
Pfitzer 1974
Bird
1979
Mead and
Williams
1965
Chapman-Ferraro approach
to modeling the closed tail
Siscoe
1966
Spreiter
and Alksne
1969
Unti and
Atkinson
1968
Prescribed magnetopause approach
to modeling the closed tail
Voigt
stretch
model
Schulz
source
surface
model
Schulz
source
surface
model
Analytic tail approximations
and convection:
The Birn-Schindler project
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but superceded by computational solutions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
Modules for the Open Magnetosphere:
• The Stern-singularity problem
• The Toffoletto-Hill solution
• Region 1 current modeling
• The SSM (Peroomian) extension
The Stern-singularity problem
Siscoe
1988
E parallel
T-H and SSM compared
T-H
SSM (P)
Region 1 Currents:
SSM (P)
Peroomian
et al. 1991
Siscoe
et al. 1991
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
Vasyliunas 1970
Jaggi & Wolf 1973
Magnetosphere-Ionosphere
Coupling Modules
Rice Convection Model (RCM)
The Wolf & Co. project
RCM Master Plan
RCM + UCLA MHD Code (Toffoletto 2000)
Summary of MI Coupling Epoch:
• Well posed fully explicit
• Analytic solutions possible
superceded by computations
• Assumed potential
and plasma at boundaries
• Inner magnetosphere
plasma modeled
• Physical region 2 currents
• No region 1 currents
• First RCM-MHD results
Equilibrium RCM
Toffoletto 2000
Regional MHD
Plasmoid
Kelvin-Helmholtz wave
Flux transfer event
Plasmoid Simulation
Lee et al. 1985
Kelvin-Helmholtz
Simulation
Otto & Fairfield 2000
FTE Simulation
Scholer 1989
Global MHD
• Open geometry
• Magnetospheric sash
• E-Parallel & reconnection
Open Geometry
Raeder
GGCM Web Site
Magnetospheric
Sash
0
-10
-5
-2
2
4
X=6
IMF
-1
1
3
5
IMF
+
-5
-10
+
+
X=7
+
+
6
X=8
IMF
4
2
0
-5
-10
E-Parallel & Reconnection
Future Directions
Hybrids
Other Magnetospheres
Deep Questions
Acknowledgements
Bill White
Keith Siebert
Dan Weimer
Bengt Sonnerup
Nelson Maynard
Gary Erickson
NSF
NASA
DTRA