problems in space physics 長井嗣信 東京工業大学. 磁気圏の未解決問題...
TRANSCRIPT
1. Substorm Onsets
Global Images
Intense Ground Observation Network
Mid-Tail Observations 10-30 Re
Geosynchronous Orbit 6.6 Re
Global Satellite Aurora Images
Spatial ResolutionTime ResolutionUV
Comparison with Ground Observations
Geosynchronous Substorm Signatures
Longitudinal Effect Particles or Magnetic Field
Magnetic Storms
1. Solar wind parameters Dst2. Ring current modeling (dipole field) Dst3. H+ vs. O+4. What should be known?
Particle distributionsTime, Position (L, MLT, Latitude)Energy, Species
3. Plasma Convection
Plasma Transport = Field Transport
Pictures from Ground Observations
Pictures from Tail Observations
Polar Cap Potential Drop 100 kVPolar Cap > 75 degrees L = 2 x 3.14 x 6371.2 x 30/360 = 3300 kmE = 100kV / 3300km = 30 mV/mB = 60000 nT V = E/B = 30 mV/m / 60000 nT = 500 m/sT = 3300km / 500 m/s = 100 min
Vsw = 500 km/sT = 100 Re/500 km/s = 20 min
Plasma Convection in the Tail
Stationary vs Bursty
Paterson et al. JGR 1998
100 Re/10 km/s = 1000 min Angelopoulos et al. 1999
Mid- and Near-Tail Plasma Observations
1. Plasmas are NOT MHD
2. Problems in the Present Instruments
No Convincing Observations
4. IMF Bz Control for the Plasma Sheet
1. IMF Bz > 0 (northward)
2. IMF Bz < 0 (southward)
3. ssc (density increase in SW)
IMF Bz Effect
SubstormsIMF Bz Northward Turning > 50%IMF Bz > 0 Substorm Processes
Prolonged IMF Bz PeriodsCold and Dense PlasmasStationary
Summary
1. Importance of Ground ObservationsOptical Aurora
2. Ionospheric SignaturesNorth / South Conjugate
3. IMF Bz ControlDrastic Changes