HR: 0800h
AN: SM41A-0327    [Abstracts]
TI: The Typical Auroral Substorm: A Bifurcated Oval
AU: Hoffman, R A
AF: NASA-GSFC, Space Weather Laboratory, Code 674 NASA/Goddard Space Flight Center, Greenbelt, MD 20771, United States
AU: * Gjerloev, J
EM: jesper.gjerloev@jhuapl.edu
AF: JHU-APL, Applied Physics Laboratory Johns Hopkins University 11100 Johns Hopkins Road, Laurel, MD 20723, United States
AB: Utilizing global auroral images obtained by Polar VIS Earth Camera we have analyzed the UV emissions from 116 classical auroral substorms. Average auroral emission patterns were deduced for 11 time steps of the substorm covering 20 min prior to the onset until well into the recovery phase. These average patterns were based on a three step normalization technique, one temporal and two spatial. Based on this study we can make the following conclusions. The normalization technique is highly efficient in minimizing the smearing of key features in the auroral emission pattern. We can conclude that even though the individual events may vary significantly in intensity, size, position and lifetime all have the same key emission features and can be represented by our average patterns. Thus our normalization results quantitatively validate the Akasofu assumption that key auroral features exist in the bulge-type auroral substorm. After the onset the auroral oval is clearly bifurcated consisting of two components: the oval aurora in the latitude range of the pre-onset oval, and the bulge aurora, which emerges out of the oval, expanding poleward and both east and west in MLT. Due to the pronounced difference in spatiotemporal behavior of the two auroral components we speculate that they are quasi independent, and thus the sources of electrons must also be independent.
DE: 2409 Current systems (2721)
DE: 2788 Magnetic storms and substorms (7954)
DE: 2790 Substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting