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Cluster, THEMIS, & Geotail Conjunction Event on 11 July 2008

Cluster, THEMIS, & Geotail Conjunction Event on 11 July 2008. Hiroshi Hasegawa ISAS/JAXA. Overview (2008-07-11). TH-B monitoring the solar wind & IMF. Three intervals of interest:

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Cluster, THEMIS, & Geotail Conjunction Event on 11 July 2008

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  1. Cluster, THEMIS, & Geotail Conjunction Event on 11 July 2008 Hiroshi Hasegawa ISAS/JAXA

  2. Overview (2008-07-11) • TH-B monitoring the solar wind & IMF. • Three intervals of interest: 1. 0100-1100 UT: Cluster on the dawn flank, Geotail on the dusk flank, under changing IMF direction (both south of equator). 2. 1600-2000 UT: TH-A, D, & E at the post-noon magnetopause, Geotail on the dusk flank, under northward IMF. 3. 2000-2200 UT: TH-C, D, & E downstream of or near the parallel shock, TH-A near the magnetopause, under Bx-dominant IMF.

  3. CL A,D,E TH-B A,D,E GTL TH-C GTL CL

  4. ACE 0-24 UT 1 2 3 IMF |B|: 4-14 nT Bx By <~ 0 Bz Density Total Velocity

  5. TH-B in SW (0-24 UT)

  6. Cluster at dawn (0-12 UT)

  7. Geotail at dusk (0-11 UT)

  8. Cluster at dawn (01-11 UT) TH-B

  9. Cluster & Geotail (02-05 UT)Magnetic dips in both dawn & dusk BLs

  10. What could be pursued? • Magnetic topology of the boundary layer? - What features do ion & electron velocity distributions have? • Response of the boundary layer to temporal changes in the IMF orientation? - Some ground/aurora signatures? • Latitudinal dependence of KH wave activity? - May be meaningful to report the absence of clear KH activity at those (somewhat high) latitudes.

  11. ACE 0-24 UT 1 2 3 IMF |B|: 4-14 nT Bx By <~ 0 Bz Density Total Velocity

  12. A,D,E TH-B A,D,E GTL TH-C GTL

  13. TH-A 1600 1800 2400

  14. TH-A TH-D Reconnection in sheath or at MP southward flow 1700 1800 1600 1700 1800

  15. TH-E TH-A southward flow KH-like quasi-periodicity southward flow 1800 1800 2000

  16. Southward flow in the dayside BL from northern lobe reconnection Li et al., JGR, 2009

  17. Reconnection in Summer hemisphere Li et al., JGR, 2009

  18. 2-component ions at dusk

  19. Quasi-periodic tailward-propagating Alfvén waves,possibly mode-converted from KH waves By Bz Vy Vz

  20. Summary of NBZ interval • Simultaneous operation of lobe reconnection and the KH instability? • Southward flow from lobe reconnection in the summer hemisphere confirmed. - Dayside BL formed via lobe reconnection. • KH-associated(?) oscillations at X~-25 Re. • Reconnection jets when the IMF orientation is changing. In sheath or at magnetopause? • Role(s) of KHI in further SW entry and/or in tailward/inward transport of the dayside CD plasma?

  21. IMF Bx-dominated interval

  22. 20-22 UTTH-A in SW Some foreshock activity at X = 27 Re

  23. 20-22 UTTH-E at (x,y)~(8, 7)Re BS N & V fluctuations in association with B fluctuations. Some sheath structures may have excess dynamic P.

  24. 20-22 UTTH-D at (x,y)~(8, 8)Re BS

  25. 20-22 UTTH-C at (x,y)~(6, 10)Re BS Weaker B fluctuations than near local noon.

  26. 20-22 UTTH-A at (x,y)~(4, 9)Re MP Several MP crossings probably due to enhanced dynamic P in sheath. No or thin BL in later interval.

  27. What could be pursued? • Spatial dependenceof magnetosheath magnetic fluctuations/turbulence? • Correspondence between magnetosheath fluctuations and MP crossings? - Some sheath structures may have excess dynamic pressure. • Disappearance/erosion of dayside CD BL when IMF Bz changed from northward to ~0.

  28. 1st interval: 01-11 UT on 11 July 2008 Simultaneous observations of dawn (Cluster) & dusk (Geotail) tail-flank boundary layers under varying IMF orientation • Yulia: analyze PEACE electron pitch-angle distributions, to clarify magnetic topology of the boundary layer. • Qing-He: investigate SuperDARN data, to see response/change of ionospheric convection to IMF orientation change. • Hiroshi: check CIS velocity distributions, to find additional signatures to reveal the topology.

  29. 2nd interval: 16-21 UT on 11 July 2008 Simultaneous operation of lobe reconnection & KH instability under northward IMF? • Qing-He?, Harald?: ionospheric/aurora signatures of lobe reconnection in the northern hemisphere? • Jean: run simulation to compare with Themis (southward flow from northern lobe reconnection) & Geotail (stagnant, dense dusk-flank boundary layer) observations • Yulia: analyze PEACE data from the dawn tail-flank • Hiroshi: reconstruct Themis KH-like BL structures • Who?: analyze particle (ion/ele) signatures of lobe reconnection

  30. 2nd interval: 16-21 UT on 11 July 2008 Reconnection in the magnetosheath(?) under IMF orientation change • Jue?: in-depth analysis of reconnection jets (Walen test, particle signatures, component/anti-parallel?) • Hiroshi: reconstruct reconnection jets?

  31. 3rd interval: 20-22 UT on 11 July 2008 Spatial structures of magnetosheath fluctuations/ turbulenceunder Bx-dominated IMF conditions • Who could lead? Response of the magnetopause/boundary layer to magnetosheath fluctuations under Bx-dominated IMF conditions (Who could lead?) • Correspondence between magnetosheath fluctuations and MP crossings? - Some sheath structures may have excess dynamic pressure. • Disappearance/erosion of dayside CD BL when IMF Bz changed from northward to ~0.

  32. Cluster at dawn (0-12 UT)

  33. CL CL TH-B A,D,E GTL TH-C GTL

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