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Possible multiple acceleration sites during a substorm event : 1st March 2008

Possible multiple acceleration sites during a substorm event : 1st March 2008. 1h45 – 2h10. A. Tallet, C. Jacquey, O. Le Contel, H. Frey, V. Génot, P. Louarn, G. Fruit, B. Lavraud, J.A. Sauvaud, A. Roux, V. Angelopoulos, D. Sibeck, J.P. McFadden, D. Larson, U. Auster, H. Singer. GOES-12. P4.

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Possible multiple acceleration sites during a substorm event : 1st March 2008

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  1. Possible multiple acceleration sites during a substorm event : 1st March 2008 1h45 – 2h10 A. Tallet, C. Jacquey, O. Le Contel, H. Frey, V. Génot, P. Louarn, G. Fruit, B. Lavraud, J.A. Sauvaud, A. Roux, V. Angelopoulos, D. Sibeck, J.P. McFadden, D. Larson, U. Auster, H. Singer

  2. GOES-12 P4 Geotail P2 P1 P3 P5 P1 P2 P4 P3 GOES-12 01:55:00 UT

  3. Large scale features

  4. Solar Wind ? No significative variation of velocity and pressure

  5. Substorm

  6. Mid Tail Observations

  7. Mid Tail Observations 01:49:23 01:55:11 01:49:23 First tailward flow onset & magnetic perturbation 01:55:11 Second perturbation magnetic → solitary By perturbation →DBz similar to plasmoid/Xline

  8. Mid Tail Observations 01:48:32 01:54:45 01:48:32 First tailward flow onset & magnetic perturbation 01:54:45 Second perturbation magnetic → DBz similar to plasmoid BUTDBy →vflow~300 km/s

  9. Near Earth Observations

  10. Near-Earth Tail Observations 01:55:16 01:55:16DB DN DT ESA Flow → Bz increases & vy<0

  11. Near-Earth Tail Observations 01:54:47 01:54:57DB DN DT ESA flow → Bz increases & vy<0

  12. Near-Earth Tail Observations GOES-12 ? 01:54 ± 30s 01:56 ± 30s

  13. Quasi-simultaneous, DX ~9 Re, Dt ~1-6 s Second Event ? First Event ?

  14. First Event • 1: C(P2), 01:48:32 • 2: B(P1), 01:49:02 • Tailward propagation from C to B V ~1120 km/s • The perturbation was detected close to the neutral sheet at both locations • No significant counter part observed at D, E and GOES-12 • Tailward flow in the mid tail (C and B) : • Vflow << Vpropagation • → a wave rather than a struture

  15. Second Event • 1: C(P2), 01:54:45 • 2: E(P4), 01:54:46 • 3: B(P1), 01:55:11 • 4: D(P3), 01:55:16 • 5: G12, 01:54 ± 30s ? • 01:56 ± 30s ? • Tailward propagation from C to B: • V = ~ 1300 km/s • Perturbations have been detected quasi-simultaneously at C and E • There is 1 source between both fortuitously initiated at a location such as: Ve.dt = -Vt.dt • Or There are 2 sources (likely coupled) • Significant delay from E to D  the source is very localised Earthward propagation Tailward propagation ? • Tailward flow in the mid tail (C and B) : • Vflow << Vpropagation • → a wave rather than a struture

  16. First hypothesis : one source 1: C(P2), 01:54:45 2: E(P4), 01:54:46 3: B(P1), 01:55:11 4: D(P3), 01:55:16 5: G12, 01:56 ± 30s ? Tailward flow → Vflow ~ 300km/s propagate tailward at Vprop ~ 1300km/s 01:56 ± 30s Earthward propagation

  17. First hypothesis : one source 1: G12, 01:54 ± 30s ? 2: C(P2), 01:54:45 2: E(P4), 01:54:46 3: B(P1), 01:55:11 4: D(P3), 01:55:16 Tailward flow propagating tailward 01:54 ± 30s • One source between G12 and TH-E, propagating tailward (azimutaly) up to TH-D • Quasi-simultaneous effect on C and E • Very slow propagation between E and D : ~110 km/s Scenario not very consistent

  18. Second hypothesis : two sources! 1: G12, 01:54 ± 30s ? 2: C(P2), 01:54:45 2: E(P4), 01:54:46 3: B(P1), 01:55:11 4: D(P3), 01:55:16 01:54 ± 30s • Two sources : one near to G12 and one near to C • Sources coupled because quasi-simultaneous between C and E Sources coupled !

  19. 01:54:33 01:55:51 01:54 01:54:45 01:55:54 01:56:12 01:54:54 01:55:57 01:56:15 01:55:12 01:56:00 01:56:18 01:55:39 01:56:03 01:56:21

  20. Conclusion • Multiple sources ? • Coupled ? • Nature of the perturbation on the tail satellites ? Wave ? • |DBy| > |DBz| • vflow << vpropagation • UpcomingAnalysis steps: • - Precise timing on GOES-12 • - Local expansion of the acceleration region on D and E • - Ground data analysis

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