1. Magnetic Reconnection in the Earth's Magnetosphere Tatsuki Ogino Solar-Terrestrial Environment Laboratory, Nagoya University 3-13 Honohara, Toyokawa, Aichi 442-8507, Japan

3. 複合系の物理 外からの作用 開放系 磁気圏 直接作用 対流（ Poynting Flux ） 外への流出 蓄積作用 プラズマ 磁場（電流） 光・電磁波の反射・放射 太陽風 地球起源イオン流出 結合系 渦度 沿磁力線電流 降下粒子 重イオン流出 窓 磁気リコネクション 太陽からの作用 エネルギーと物質 光・電磁波 太陽風 惑星間磁場（ IMF ） 循環 蓄積 エネルギー 消費 窓 磁気リコネクション 内部自立系 電磁圏・熱圏 （オーロラ） 太陽地球システムの特徴

4. 磁気圏と電離圏の 大域的と局所的な 関係を調べる 磁気圏エネルギー 輸送をマクロとミクロな 物理から調べる

5. Solar Wind and Magnetosphere Interaction Two important mechanism 1. Magnetic reconnection 2. Viscous interaction Kelvin-Helmholtz instability magnetic reconnection >> viscous interaction

6. 2. Viscous interaction Kelvin-Helmholtz instability (Miura)

7. 1. Magnetic reconnection Dungey (1961)

8. Magnetic Reconnection of Earth's Magnetosphere 1. Effect of IMF Bz component southward IMF versus northward IMF Southward IMF Northward IMF

10. Magnetic reconnection may be the most dominant mechanism. 1. How well the antiparallel field condition is satisfied. 2. How slow the relative velocity between the reconnection magnetic field lines is.

11. How much can the reconnection process be understood by a superposition of the IMF and geomagnetic field? What are different from a simple superposition? (1) Movement of the reconnection field lines (convection) (2) Configuration of the reconnection region might change remarkably (3) Temporal variation of reconnection process (intermittency)

12. Simple Superposition of the Geomagnetic Field and IMF Bx>0, By<0, Bz=0 Bx>0, By<0, Bz=-Bx

13. solar wind MP flow normal to MP flow along MP Perpendicular flow to magnetopause (normal flow to reconnection line) Parallel flow along magnetopause (convection)

14. solar wind tailword flow convection Parallel flow along magnetopause (Tailward convection) normal flow to reconnection line

15. Problems of dayside magnetic reconnection in the earth’s magnetosphere 1. Can the reconnection rate be understood by ? Where (movement of place, 3D structure) When (temporal variation) 2. Can the reconnection potential φ MR be distinguished from the polar cap potential φ PC ? Length of reconnection line (?) φ PC increases when the reconnected magnetic field lines are carried with the solar wind 3. Total amount of reconnection rate → Total flux across the open- closed boundary This measure is quite difficult V , E 

17. Where magnetic reconnection occurs in the magnetosphere ・ Antiparallel condition Angle of reconnected field lines, θ Magnitude of reconnected field lines ・ Relative velocity of reconnected field lines ( ) Inclination of the magnetic dipole axis Weakest place of magnitude along the field lines Antiparallel field condition Magnetic equator reconnection line magnetic equator

18. 2. Effect of IMF By and Bz Two important conditions (1) Anti-parallel field condition (2) Magnetosheath plasma flow How far is the reconnection region from the subsolar point.

19. 名古屋大学太陽地球環境研究所 共同観測情報センター・教授 荻野竜樹 コンピュータで見るジオスペース

21. Southward IMF Northward IMF

23. 2. Effect of dipole tilt Tilt angle is 30 degrees

24. Southward IMF Bz -5nT Northward IMF Bz 5nT Tilt Angle θ=30° Z Z X X 15Re -15Re 15Re -15Re -60Re 3D Magnetic Field Line Magnetic Equator

25. Tilt Angle θ=30° Z Z X X 30Re -30Re 30Re -30Re -120Re Plasma Pressure Southward IMF Bz -5nT Northward IMF Bz 5nT

26. -30Re 30Re -30Re 30Re Y Z -30Re 30Re -30Re 30Re Y Z X=-15Re Southward IMF Bz -5nT Northward IMF Bz 5nT Plasma Pressure

27. TAIL BOUNDARY Comparison of Shape of the Neutral Sheet Between Simulation and Observations by Fairfield and Gosling (Gosling et al. 1986 ) F ･･･ Fairfield near –30Re FS ･･･ Fairfield near –20Re G ･･･ Gosling near –15Re G -30Re 30Re -30Re 30Re Y Z Southward IMF Bz -5nT

28. 3D visualization by VRML (Virtual Reality Modeling Language) dipole tilt and southward IMF

30. Dipole Tilt Magnetic Equator Hinging Point θ Reconnection Point (X= ‐ 10 ～‐ 20Re) Magnetic Axis Reconnection Point Hinging Distance(10Re) Southward IMF

31. dipole tilt and northward IMF

33. Dipole Tilt Northward IMF Magnetic Axis Magnetic Equator Reconnection Point

34. Kinetic Thermal Poynting Kinetic Thermal Magnetic Energy Energy Flux

35. θ=30°θ=0° X (Re) Kinetic Magnetic Thermal Energy 3000 00 10 -3 エネルギー [J/m] Thermal エネルギー [J/m] Energy

36. tailward Thermal Energy Flux θ=30°θ=0° tailward Poynting sunward Poynting 10 -4 00 X (Re) 30 00 エネルギーフラックス [J/s] tailward Kinetic エネルギーフラックス [J/s] Energy Flux

37. 3. Effect of dipole Tilt and IMF By component Tilt angle is 30 degrees Northern hemisphere is smmer

41. Configuration of 3D magnetic field lines for dipole tilt and IMF By-component

42. B IMF Magnetic Equator Reconnection for existence of dipole tile and IMF By Geomagnetic field Anti-parallel reconnection Divergent flow From the subsolar point

43. Figure 6. Ionospheric convection and potential in polar region Green line is open-closed boundary Comparison of throat regions in summer and winter Summer and Northern Hemisphere Winter and Southern Hemisphere 12 18 00 18 06 00 12 Convection pattern, Energy flux Potential χ = 30 º, θ= 315 º A

44. 100 50 0 -50 (KV) 90 °180 ° 270 ° 0 °270° summer winter - +-+- + - - +-+- + - Angle of IMF Polar cap potential versus IMF angle

45. Summary 1. A almost closed magnetosphere is formed for pure northward IMF and no dipole tilt because high latitude tail reconnection simultaneously occurs in both hemispheres. 2. If there exists finite IMF By component, the earth's magnetosphere becomes open. 3. When the IMF has small duskward component (Bz>0 and By>0), magnetopause reconnection occurs in dusk side and high latitude region in the northern hemisphere. Open field lines become rich in the dawn polar region because reconnected open field lines convect from dusk to dawn in the dayside polar region. 4. If the dipole tilt exists, the earth's magnetosphere becomes again open even for pure northward IMF and a north-south asymmetry appears. Dayside reconnection occurs near the magnetic equator where the geomagnetic field is weakest along the field lines.

46. 5. When the dipole tilt and IMF By and Bz components simultaneously exist, a complicated structure without any symmetric plane is formed in the magnetosphere. 6. Anti-parallel reconnection is the primary phenomenon at the dayside magnetopause for a finite By component and southward IMF when the dipole tilt exists. 7. This is because reconnection around the magnetic equator and noon-midnight meridian is suppressed due to poor satisfaction of anti-parallel field condition and increase of magnetosheath flow, and it occurs in the split anti-parallel field regions. 8. Polar convection in throat region becomes more east-west direction in summer hemisphere and that does more noon-midnight direction in winter hemisphere.

47. Earth Sun 4. Effect of IMF Bx component Parker spiral

48. Duskward IMF B=15nT, Bx=-By and Bz=0 Bx<0 X Y

49. B=15nT, Bx=-By and Bz=|Bx| Bx<0 X Y

50. Duskward and southward IMF B=15nT, Bx=-By and Bz= -|Bx| Bx<0 X Y

51. Dawn-dusk asymmetry of the plasma temperature, B=12.2nT, Bx=-By and Bz= -|Bx| Duskward IMF B=12.2nT, Bx=-By and Bz=-|Bx| Ms=Vsw/Vth=4.04 Ma=Vsw/Val=3.08 M = Vsw/Vfms=2.45

52. x 30Re x 30Re y 30Re z 30Re y 30Re -120Re Duskward IMF B=12.2nT, Bx=-By and Bz=- |Bx| Ms=Vsw/Vth=4.04 Ma=Vsw/Val=3.08 M = Vsw/Vfms=2.45

53. x 30Re x 30Re y 30Re z 30Re y 30Re Duskward IMF B=12.2nT, Bx=-By and Bz=-|Bx| Ms=Vsw/Vth=4.04 Ma=Vsw/Val=3.08 M = Vsw/Vfms=2.45

54. Duskward IMF B=15.0nT, Bx=-By and Bz=-|Bx| Ms=Vsw/Vth=4.04 Ma=Vsw/Val=2.05 M = Vsw/Vfms=1.83

55. Duskward IMF B=15.0nT, Bx=-By and Bz=- |Bx| Ms=Vsw/Vth=4.04 Ma=Vsw/Val=2.05 M = Vsw/Vfms=1.83

56. y 30Re x 30Re Duskward IMF B=15.0nT, Bx=-By and Bz=-|Bx| Ms=Vsw/Vth=4.04 Ma=Vsw/Val=2.05 M = Vsw/Vfms=1.83

57. Dawnward IMF B=12.2nT, Bx=-By and Bz=-|Bx| Dawnward IMF B=12.2nT, Bx=-By and Bz=-|Bx| Ms=Vsw/Vth=6.39 Ma=Vsw/Val=3.08 M = Vsw/Vfms=2.78

58. Simulation Results Parker spiral with IMF Bx component creates a transient phenomenon with dawn-dusk and north-south asymmetries in the earth's magnetosphere, and the asymmetric structure is kept well in a quasi-steady state even for a small IMF Bx component. When the IMF becomes large and the Alfven Mach number becomes less than about two, the asymmetric structure appears even in the magnetosheath and becomes remarkable in the magnetosphere. Through the bow shock the IMF increases and the plasma flow decreases according to the Rankine-Hugoniot relationship. Therefore the plasma flow is easily influenced by the IMF in the magnetosheath and asymmetry appears by the effect of IMF Bx.

59. Summary For non-zero IMF Bx in Parker spiral, magnetopause magnetic reconnection occurs differently on dawn and dusk sides. The reconnection sites shift sunward on dawn and tailward on dusk. IMF lines on dusk are straighter than those on dawn. This increases the magnetic pressure on dusk and pushes the plasma sheet toward dawn. On the other hand, the IMF lines on dawn are bent sharply. This decreases the magnetic pressure. The dawn-dusk asymmetry and the related magnetospheric convection are the main cawses that the plasma sheet shifts up/down from equator and is inclined, and the magnetotail is rotated to the sun-earth line. This also causes asymmetric plasma flows and the tendency is largely enhanced for smaller Alfven Mach number (<2). This dawn-dusk asymmetric occurrence of dayside reconnection and induced magnetospheric convection become main causes to create inclination of plasma sheet, rotation magnetotail and also asymmetric plasma flows in the tail. As the results, tail reconnection favorably occurs in dusk side due to the effects of the IMF Bx component namely, the Parker spiral effect.

60. MHD Simulation of the Solar Wind-Magnetosphere Interaction of the Shock Wave Event on October 24, 2003

61. Occurrence of Abnormal Operation in a Satellite for Environment Observation Technology, ADEOS-II (Midori-II) 10/24 16:13-16:17 UT Lowering of the electric power generated by the solar cell (10/25 01:13-01:17 JST) 15:25 UT Occurrence of SC in the Kakioka geomagnetic data 15:40 UT The maximum of about 2000 nT in AE 00:00-24:00 UT Magnetic storm did not occur (Dst > -65 nT)

62. Relative Location of ISTP Constellation during Sun-Earth Connection Event SOHOWIND Geotail Interball-Tail Polar 10 Re 100 Re 220Re EarthSun ACE

64. Bz By P V n 001224 10:0017:00

66. 15:40UT Oct. 2003

67. 16:01 UT Oct. 2003

68. Simulation Results Magnetopause approaches the geosynchronous orbit after the shock wave arrives. Plasma sheet goes around the dayside magnetosphere from the magnetotail along magnetospheric convection. Hot plasma of the plasma sheet fills the geosynchronous region by the magnetospheric convection. Inclination of the plasma sheet is reversed in y-z cross section as the IMF By changes from negative to positive at 15:30 UT. In the case, the plasma sheet is twisted, a plasma extension (or lobe bifurcation) appears and the plasma sheet extension seems to connect with the earth's ionosphere.