Two-step evolution of auroral acceleration at substorm onset

Details Two-step evolution of auroral acceleration at substorm onset Two-step evolution of auroral acceleration at substorm onset

Nov 2010

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010jgra..11511213m&link_type=abstract

Journal of Geophysical Research, Volume 115, Issue A11, CiteID A11213

Physics

5

Magnetospheric Physics: Substorms, Magnetospheric Physics: Auroral Phenomena (2407), Ionosphere: Ionosphere/Magnetosphere Interactions (2736), Magnetospheric Physics: Energetic Particles: Precipitating, Magnetospheric Physics: Energetic Particles: Trapped

Scientific paper

The sudden formation of parallel electric fields in the magnetosphere-ionosphere (M-I) coupling system is essential to complete substorm onset. From this standpoint, we focus substorm ignition on field-aligned acceleration by studying the dynamical behavior of auroral kilometric radiation. Field-aligned auroral acceleration shows a distinct two-step evolution at substorm onset: the activation of low-altitude acceleration (h ˜ 4000-5000 km) which corresponds to auroral initial brightening and the subsequent abrupt breakout of high-altitude acceleration (h ˜ 6000-12,000 km) which corresponds to auroral breakup. Cases when only low-altitude acceleration (first-step evolution) is activated are pseudosubstorms. This indicates that the second evolution of field-aligned acceleration divides full substorm from pseudosubstorm. The statistical relationship between the plasma flow burst in the plasma sheet and its response to the M-I coupling region shows that about 65% of flow bursts cause pseudobreakup/initial brightening (low-altitude acceleration) and one third of them develops into full substorm (low-altitude and high-altitude accelerations), while the magnitude of flow velocity does not necessarily distinguish between pseudobreakup and full substorm. This suggests that some plasma flow bursts originate field-aligned current which first enhance low-altitude acceleration, and the increasing field-aligned current induces second acceleration above the preexisting low-altitude acceleration as a consequence of current/current-driven instabilities. In this sense, the substorm is finally ignited in the auroral M-I coupling region.

Affiliated with

Also associated with

No associations

Rating

Two-step evolution of auroral acceleration at substorm onset 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 Two-step evolution of auroral acceleration at substorm onset, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Two-step evolution of auroral acceleration at substorm onset will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1488739