Timing analysis of a substorm event on January 29, 2008 observed by THEMIS: multiple intensifications, current disruptions and plasmoids. Jacquey C., O.

Présentation au sujet: "Timing analysis of a substorm event on January 29, 2008 observed by THEMIS: multiple intensifications, current disruptions and plasmoids. Jacquey C., O."— Transcription de la présentation:

1 Timing analysis of a substorm event on January 29, 2008 observed by THEMIS: multiple intensifications, current disruptions and plasmoids. Jacquey C., O. LeContel, A. Tallet, 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 ICS-9, May 6, 2008

2 G12 D C E GTL CL B C D E G12 Mid-tail Near-Earth tail

3 Global energy assessment
ICI, IL S’aGIT JUSTE DE DIRE (1) QU’IL N’Y A PAS DE VARIATION DE LA PRESSION DU VENT SOLAIRE et (2) QU’ON A A FAIRE A UN SOUS-ORAGES QUI SEMBLE TYPIQUE (UNE DIPOLARISATION A L’ORBITE GEOSTATIONNAIRE), MAIS QU’EN FAIT ON A 4 INTENSIFICATION SUCCESSIVES, DON’T LA TROISIEME EST LE MAIN SUBSTORM 4intensifications successives vues dans la queue proche. Les deux premiers ne sont associé qu’à des perturb de faible amplitude dans la queue moyenne. La diisipation à grande échelle s’opére à partir du 3eme. Dans la queu moyenne (C et B), la propagation tailward des sites de dissipation est déjà apparente à cette échelle. 4 successive events: 2 pseudo-breakups 1 substorm including 2 intensifications Static pressure: Ps = Pm + P┴i (ESA) + P┴i (SST)

4 Xo: “detachment point” of the plasmoid
B Xo: “detachment point” of the plasmoid  Initial location of the disruption Differential timing analysis  Event 1: V = 340 LB = 15 Xo = -6.8 DPs/Pso ~ 12 Event 2: V = 525 LB = 8.5 Xo = -9.5 DPs/Pso ~ 13 (km/s) (Re) (%) Vx (km/s)

5 3 successive V-shaped BZ signature associated with pressure decrease
Blob, Ps Xo C B BZ (Jacquey et al., 1991, Ohtani et al., 1992) To V1 ~ 640 km/s Xo1 ~ -13 Re V2 ~ 450 km/s Xo2 ~ -8 Re To de l’event 3: Début de decrease of BZ on both s/c + début de decroissanse de la Ps sur C. MAIS, la dissipation semble (encore) procéder par steps successifs: Un petit bordel juste avant (trait vert) quasi-insignifiant, puis le début de la dissipation principale sur C. On voit 2 sous-structures sur BZ de chacun des 2 s/c => possible: 2 current reductions successives. 3 successive V-shaped BZ signature associated with pressure decrease  3 successive tailward propagating current disruptions/reductions ?

6 Timing comparison near-Earth/mid-tail probes
< 1’ 55 sec < 1’ 25 sec -2’43’’ -163 sec < 1’ 10 sec Traits verticaux rouges :: “onsets” des signatures sur les satellites de queue (C et B), cad, DBZ en général

7 Timing synthesis [X,Y] location: thD: -9.7 ; 1.4 thE: -8.5; 2.3
Event 1 Event 2 Event 3 Xo: / (inferred from C and B) Tailward Earthward Earthward (Propagation inferred Dawnward Duskward Duskward from timing D/E) thD: Tailward ??? Earthward (Local propagation thE: Tailward ??? Earthward inferred from energetic ion anisotropy (not shown)

8 Conclusions (preliminary)
Overall consistency of the timing of the observed features Quasi-periodic intensifications, T ~ 16 min. Plasmoids/TCR Initiated close to the Earth (R < 10 Re) Clear TCR signature at 29 Re, but ambiguous ones at 18 Re (alternative: tailward propagating disruption) Associated with dipolarisation and particle acceleration in the near-Earth tail Speed: V ~ km/s; Length: 8 – 15 Re The main substorm Initiated in the near-Earth tail (~13 Re and/or 8 Re) Earthward propagating injection/dipolarisation seems to develop by successive discrete steps Lobe magnetic field changes consistent with tailward propagating current disruptions (or reductions) Each event was associated with large amplitude flow oscillation at ~2 min in the near-Earth tail. Difficile de recadrer cela par rapport au IN-OUT ou OUT-IN models. Main substorm