The optical manifestation of dispersive field‐aligned bursts in auroral breakup arcs

DOI Web Site Web Site 被引用文献3件
  • H. Dahlgren
    Department of Electrical and Computer Engineering and Center for Space Physics Boston University Boston Massachusetts USA
  • J. L. Semeter
    Department of Electrical and Computer Engineering and Center for Space Physics Boston University Boston Massachusetts USA
  • R. A. Marshall
    Department of Aeronautics and Astronautics Stanford University Stanford California USA
  • M. Zettergren
    Physical Sciences Department Embry‐Riddle Aeronautical University Daytona Beach Florida USA

書誌事項

公開日
2013-07
権利情報
  • http://onlinelibrary.wiley.com/termsAndConditions#vor
DOI
  • 10.1002/jgra.50415
公開者
American Geophysical Union (AGU)

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説明

<jats:p>High‐resolution optical observations of a substorm expansion show dynamic auroral rays with surges of luminosity traveling up the magnetic field lines. Observed in ground‐based imagers, this phenomenon has been termed auroral flames, whereas the rocket signatures of the corresponding energy dispersions are more commonly known as field‐aligned bursts. In this paper, observations of auroral flames obtained at 50 frames/s with a scientific‐grade Complementary Metal Oxide Semiconductor (CMOS) sensor (30° × 30° field of view, 30 m resolution at 120 km) are used to provide insight into the nature of the precipitating electrons similar to high‐resolution particle detectors. Thanks to the large field of view and high spatial resolution of this system, it is possible to obtain a first‐order estimate of the temporal evolution in altitude of the volume emission rate from a single sensor. The measured volume emission rates are compared with the sum of modeled eigenprofiles obtained for a finite set of electron beams with varying energy provided by the TRANSCAR auroral flux tube model. The energy dispersion signatures within each auroral ray can be analyzed in detail during a fraction of a second. The evolution of energy and flux of the precipitation shows precipitation spanning over a large range of energies, with the characteristic energy dropping from 2.1 keV to 0.87 keV over 0.2 s. Oscillations at 2.4 Hz in the magnetic zenith correspond to the period of the auroral flames, and the acceleration is believed to be due to Alfvenic wave interaction with electrons above the ionosphere.</jats:p>

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