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 10-30 Re

Geosynchronous Orbit 6.6 Re

L. A. Frank ICS-4 (1998)

January 12, 1997 0726 UT

Polar/UVI by A. Ieda 0725:11 UT

Polar/UVI January 12, 1997

0724:54 UT

0725 UT

0725 UT

0723 UT

Gang LuJGR 1999

Gang LuJGR 1999

70

70

Kadokura (2002)SIT-TV at Syowa427.8 nm

Problems

1. Spatial Resolution2. Time Resolution3. UV4. Magnetic Field Tracing5. Conjugate Events

L. R. Lyons et al. JGR 2001

L. R. Lyons et al., JGR 2001

10E

71.3 E

105E

141 E

192.5 E

322.5E

Geographic Longitude Geomag. Lat.

1.5

-8.3

-10.4

-8.7

-1.1

8.6

Global Satellite Aurora Images

Spatial ResolutionTime ResolutionUV

Comparison with Ground Observations

Geosynchronous Substorm Signatures

Longitudinal Effect Particles or Magnetic Field

McPherron 1991 Kamide and Baumjohann 1993

Burton et al., 1975

2. 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 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

Nishitani et al. JGR 2001

Plasma Convection in the Tail

Stationary vs Bursty

Paterson et al. JGR 1998

100 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

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

Future Mission

SCOPE (Scale Coupling in Plasma Environment)

1. High time resolution in particle observations2. Full energy coverage in particle observations3. Multi-point observations to know the s/c location relative to the neutral line