Substorm current wedge driven by plasma flow vortices: THEMIS observations

Details Substorm current wedge driven by plasma flow vortices: THEMIS observations Substorm current wedge driven by plasma flow vortices: THEMIS observations

May 2009

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009jgra..11400c22k&link_type=abstract

Journal of Geophysical Research, Volume 114, Issue A12, CiteID A00C22

Physics

24

Magnetospheric Physics: Auroral Phenomena (2407), Magnetospheric Physics: Substorms, Magnetospheric Physics: Magnetosphere/Ionosphere Interactions (2431), Magnetospheric Physics: Magnetospheric Configuration And Dynamics, Magnetospheric Physics: Field-Aligned Currents And Current Systems (2409)

Scientific paper

A multipoint analysis of conjugate magnetospheric and ionospheric flow vortices during the formation of the substorm current wedge (SCW) on 19 February 2008 is presented. During the substorm, four Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft were located close to the neutral sheet in the premidnight region between 9 and 12 R E geocentric distance, of which three closely (˜1-2 R E ) clustered at ˜23 MLT and one was farther west at ˜21 MLT. The closely clustered spacecraft were engulfed by a counterclockwise plasma flow vortex, while the single spacecraft recorded a clockwise plasma flow vortex. Simultaneously, a pair of conjugate flow vortices with clockwise and counterclockwise rotation appeared in the ionosphere, as inferred from equivalent ionospheric currents. The counterclockwise space vortex, which corresponded to a downward field-aligned current, was at least 1-2 R E in diameter and had rotational flow speeds of up to 900 km/s. Current density estimates associated with the formation of the space vortex in the first 30 s yielded 2.8 nA/m2 (14 μA/m2 mapped to the ionosphere), or a total current of 1.1 × 105 A. Model calculations based on midlatitude ground magnetometer data show a gradual increase of the field-aligned current, with 1-2 × 105 A within the first minute and a peak value of 7 × 105 A after 10 min, associated with the SCW, and a matching meridian of the downward current of the SCW and the downward current (counterclockwise) space vortex. The combined ground and space observations, together with the model results, present a scenario in which the space vortices generated the field-aligned current of the SCW at the beginning of the substorm expansion phase and coupled to the ionosphere, causing the ionospheric vortices.

Affiliated with

Also associated with

No associations

Rating

Substorm current wedge driven by plasma flow vortices: THEMIS observations 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 current wedge driven by plasma flow vortices: THEMIS observations, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Substorm current wedge driven by plasma flow vortices: THEMIS observations will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-813075