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Cluster, THEMIS, & Geotail Conjunction Event on 11 July 2008 Hiroshi Hasegawa ISAS/JAXA
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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.
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TH-B TH-CGTL CL GTLA,D,E
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IMF |B|: 4-14 nT By <~ 0 Bz Bx Density Total Velocity 123 ACE 0-24 UT
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TH-B in SW (0-24 UT)
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Cluster at dawn (0-12 UT)
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Geotail at dusk (0-11 UT)
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Cluster at dawn (01-11 UT) TH-B
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Cluster & Geotail (02-05 UT) Magnetic dips in both dawn & dusk BLs
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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.
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IMF |B|: 4-14 nT By <~ 0 Bz Bx Density Total Velocity 123 ACE 0-24 UT
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TH-B TH-CGTL A,D,E
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TH-A 160018002400
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TH-ATH-D 17001800160017001800 Reconnection in sheath or at MPsouthward flow
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TH-ETH-A 1800 2000 KH-like quasi-periodicitysouthward flow
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Li et al., JGR, 2009 Southward flow in the dayside BL from northern lobe reconnection
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Reconnection in Summer hemisphere Li et al., JGR, 2009
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2-component ions at dusk
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Quasi-periodic tailward-propagating Alfvén waves, possibly mode-converted from KH waves By Bz Vy Vz
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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?
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IMF Bx-dominated interval
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20-22 UT TH-A in SW Some foreshock activity at X = 27 Re
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BS 20-22 UT TH-E at (x,y)~(8, 7)Re N & V fluctuations in association with B fluctuations. Some sheath structures may have excess dynamic P.
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20-22 UT TH-D at (x,y)~(8, 8)Re BS
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Weaker B fluctuations than near local noon. 20-22 UT TH-C at (x,y)~(6, 10)Re BS
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MP 20-22 UT TH-A at (x,y)~(4, 9)Re Several MP crossings probably due to enhanced dynamic P in sheath. No or thin BL in later interval.
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What could be pursued? Spatial dependence of 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.
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1 st 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.
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2 nd 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
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2 nd 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?
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3 rd interval: 20-22 UT on 11 July 2008 Spatial structures of magnetosheath fluctuations/ turbulence under 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.
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Cluster at dawn (0-12 UT)
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TH-B TH-CGTL CL GTL A,D,E
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