Problems in Space Physics 長井嗣信 東京工業大学

磁気圏の未解決問題 「いつも同じ話をしている」 １．容易に解決できそうだが ２．何が観測的に問題なのか ３．今後どうすべきか

1.Substorm Onsets 2.Magnetic Storms 3.Plasma Convection

1.Substorm Onsets Global Images Intense Ground Observation Network Mid-Tail Observations Re Geosynchronous Orbit 6.6 Re

L. A. Frank ICS-4 (1998) January 12, UT

Polar/UVI by A. Ieda0725:11 UT

Polar/UVI January 12, :54 UT

0725 UT

0723 UT

Gang Lu JGR 1999

Gang Lu JGR

Kadokura (2002) SIT-TV at Syowa nm

Problems 1.Spatial Resolution 2.Time Resolution 3.UV 4.Magnetic Field Tracing 5.Conjugate Events

L. R. Lyons et al. JGR 2001

L. R. Lyons et al., JGR 2001

10E 71.3 E 105E 141 E E 322.5E Geographic Longitude Geomag. Lat

Global Satellite Aurora Images Spatial Resolution Time Resolution UV Comparison with Ground Observations Geosynchronous Substorm Signatures Longitudinal Effect Particles or Magnetic Field

McPherron 1991Kamide and Baumjohann 1993

Burton et al., Magnetic Storms

Ring Current Modeling Ebihara et al. 2001, 2002

Strangeway and Johnson 1983

Strangeway and Johnson 1983

Strangeway and Johnson 1983

Magnetic Storms 1.Solar wind parameters Dst 2.Ring current modeling (dipole field) Dst 3.H+ vs. O+ 4.What should be known? Particle distributions Time, 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 kV Polar Cap > 75 degrees L = 2 x 3.14 x x 30/360 = 3300 km E = 100kV / 3300km = 30 mV/m B = nT V = E/B = 30 mV/m / nT = 500 m/s T = 3300km / 500 m/s = 100 min Vsw = 500 km/s T = 100 Re/500 km/s = 20 min

Nishitani et al. JGR 2001

Plasma Convection in the Tail Stationary vs Bursty Paterson et al. JGR Re/10 km/s = 1000 min Angelopoulos et al. 1999

A dipolarization at 10 Re (for a substorm)

Mid- and Near-Tail Plasma Observations 1.Plasmas are NOT MHD 2.Problems in the Present Instruments No Convincing Observations

今後の方向 １．確かに進歩 ２．新たな問題 ３．根本的な問題 将来計画 １．対象の明確化（絞込み） ２．何が必要とされているか ３．対象にあった観測 機械と軌道

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 Substorms IMF Bz Northward Turning > 50% IMF Bz > 0 Substorm Processes Prolonged IMF Bz Periods Cold and Dense Plasmas Stationary

Summary 1.Importance of Ground Observations Optical Aurora 2.Ionospheric Signatures North / South Conjugate 3.IMF Bz Control Drastic Changes

Future Mission SCOPE (Scale Coupling in Plasma Environment) 1.High time resolution in particle observations 2.Full energy coverage in particle observations 3.Multi-point observations to know the s/c location relative to the neutral line