Remote sensing of a near-Earth neutral line during the 5 October 2000 substorm

D. Nagata (1) , S. Machida (1) , S. Ohtani (2) , S. B. Mende (3) , Y. Saito (4) , T. Mukai (4)

1 Department of Geophysics [Kyoto]
2 APL - Johns Hopkins University Applied Physics Laboratory [Laurel, MD]
3 SSL - Space Sciences Laboratory [Berkeley]
4 ISAS - Institute of Space and Astronautical Science

In this paper we examined the continuous motions of a near-Earth neutral line during the recovery phase of the 5 October 2000 substorm. Estimation was based on the PSBL ion beam model proposed by Onsager (1991) and the Geotail observations. Estimated distances from the Earth ranged from 20 to 60 R_E and retreated tailward at velocities of 250 and 300 km/s. This event initiated with the arrival of solar wind discontinuity. Simultaneous observations of electromagnetic field and electrons indicate the existence of earthward propagating waves associated with field-aligned currents. Based on these observations, we suggest that the source of the PSBL ion beams was the retreating near-Earth neutral line formed by the compression of the magnetosphere. Two scenarios of near-Earth neutral line motion in the tail dynamics are also proposed. One is the formation of plural neutral lines to create a long plasmoid. The other is the oscillation of one neutral line between the near-Earth region and the mid-tail stagnant plasmoid.

Domaines: Océan, Atmosphère; Sciences de la Terre

D. Nagata, S. Machida, S. Ohtani, S. B. Mende, Y. Saito, et al.. Remote sensing of a near-Earth neutral line during the 5 October 2000 substorm. Annales Geophysicae, 2006, 24 (12), pp.3497-3505. ⟨hal-00318244⟩