THEORETICAL STUDY OF THE BURSTY BULK FLOWS IN EARTH’S PLASMA SHEET
Received date: 2000-11-09
Revised date: 2001-01-05
Online published: 2001-08-01
The short duration, fast moving events in the Earth’s plasma sheet have received quite a lot of attentions recently. Such events were termed bursty bulk flows after the paper by Angelopoulos et al. These flow pulses usually last for 10 minutes and have flow speed above 400 km/s. The present paper gives a brief review of the study on the bursty bulk flows. Current theory suggested that the bursty bulk flows are the flows of bubble (underpopulated magnetic flux tube) in the plasma sheet. Under the action of interchange instability, bubble is propelled earthward. Birkeland currents flow at the boundary between the bubble and the background medium, downward the ionosphere from the dawn side boundary and upward from the dusk side boundary. The cross section of a bubble at the equatorial plane would have an elongated streamline shape with the cross tail size of the order of 2 Earth radius. Bubble picture naturally explains characteristics of the bursty bulk flows observed in the plasma sheet. Some numerical simulations have reproduced the observed high-speed flow and the shape of the line of associated magnetic field. Observations have confirmed the expected bubble property, which includes its cross tail size, speed, more dipolar magnetic field, decrease in pressure and density, ionospheric and ground signatures. Both theoretic calculation and observation have demonstrated that the bursty bulk flows are the main mechanism for the magnetic flux and plasma particles transport in the Earth's plasma sheet.
Key words： Bursty bulk flows; Magnetic flux tube; Plasma sheet
CHEN Chuxin . THEORETICAL STUDY OF THE BURSTY BULK FLOWS IN EARTH’S PLASMA SHEET[J]. Advances in Earth Science, 2001 , 16(4) : 584 -586 . DOI: 10.11867/j.issn.1001-8166.2001.04.0584
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