Substorm onset timing: The December 31, 1995, event

Details Substorm onset timing: The December 31, 1995, event Substorm onset timing: The December 31, 1995, event

Oct 1999

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1999jgr...10422713o&link_type=abstract

Journal of Geophysical Research, Volume 104, Issue A10, p. 22713-22728

Physics

53

Magnetospheric Physics: Current Systems, Magnetospheric Physics: Magnetotail, Magnetospheric Physics: Plasma Sheet, Magnetospheric Physics: Storms And Substorms

Scientific paper

The objective of the present study is to examine the timing of various onset-associated signatures and address the cause-and-effect relationship between the formation of a near-Earth neutral line (NENL) and the trigger of tail current disruption. An event selected for this study took place on December 31, 1995. In this event the Geotail satellite was located at X=-30.3RE in the midnight sector at a local time between the GOES 8 and 9 geosynchronous satellites. The timing of the Geotail observation of a fast (950-km/s) tailward convection flow accompanied with southward BZ(<-10nT) indicates that the near-Earth reconnection process started at least 4 min before the ground substorm onset, which was identified by various signatures such as an auroral expansion, a Pi2 onset, a positive bay onset, and a negative bay onset. Both GOES satellites observed depolarization. GOES 9 was located closer to the onset meridian and observed a sudden recovery (depolarization) of the local magnetic field but with a noticeable (~1 min) delay from the ground onset. This delay can be interpreted in terms of the earthward expansion of tail current disruption initiated outside of geosynchronous orbit. The timing of all these features is consistent with the idea that depolarization is a pileup of magnetic flux conveyed from the NENL. However, a sharp decrease in the H component at GOES 9 prior to the local depolarization onset and the sudden start of a substorm are difficult to explain in terms of this idea. It is asserted that tail current disruption is a unique process rather than a direct consequence of the NENL formation, although it is possible that the reconnection process sets up a favorable condition for triggering tail current disruption. The fast plasma flow in the plasma sheet ceased soon after the substorm onset, suggesting that during the expansion phase, the tail current disruption took over the near-Earth reconnection process as a major role in the substorm dynamics.

Affiliated with

Also associated with

No associations

Rating

Substorm onset timing: The December 31, 1995, event does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Substorm onset timing: The December 31, 1995, event, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Substorm onset timing: The December 31, 1995, event will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1086958