Paper#: 117
Poster #:
Session Name: Plenary
Room: West Ballroom
Day: Wednesday
Time: 8:55-9:20 a.m.
Abstract Title: Insights into the Dynamics of Substorms with Simultaneous Auroral Images and In-Situ Plasma and Magnetic Field Observations
PresentSurname: Frank, L.A.
All Authors: L.A. Frank, J.B. Sigwarth, W.R. Paterson
Abstract : Simultaneous images of the auroras with the Polar spacecraft and measurements of the plasmas and magnetic fields with the Geotail spacecraft have been used to investigate the classical substorm. These substorms are not to be identified with auroral brightenings which can occur independently at higher magnetic latitudes. For the classical auroral-magnetospheric substorm the onset of instability occurs within the ring current at radial distances of about 4 to 12 RE. The dimensions of the onset for an individual storm are of the order of 1 RE or less. Tailward jetting of plasmas at speeds of about 200 km/s occurs at distances tailward of the onset region and earthward jetting with similar speeds at lesser distances. The onset instability is preceded by a flow of plasma into the ring current with speeds in the range of 50 km/s followed by a several-minute period of stagnant flow prior to the explosive onset. High-resolution auroral images were also employed to identify the passage of the plasmas associated with auroral surges over the position of the Geotail spacecraft. This spacecraft recorded earthward plasma flows of about 200 to 400 km/s for periods of several minutes as the leading edge of surge plasmas passed by. The results from recent simultaneous images of the northern and southern auroras are presented.