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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 21, issue 7
Ann. Geophys., 21, 1629–1643, 2003
https://doi.org/10.5194/angeo-21-1629-2003
© Author(s) 2003. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 21, 1629–1643, 2003
https://doi.org/10.5194/angeo-21-1629-2003
© Author(s) 2003. This work is distributed under
the Creative Commons Attribution 3.0 License.

  31 Jul 2003

31 Jul 2003

High resolution measurements and modeling of auroral hydrogen emission line profiles

B. S. Lanchester1, M. Galand2, S. C. Robertson1, M. H. Rees1, D. Lummerzheim4, I. Furniss3, L. M. Peticolas5, H. U. Frey5, J. Baumgardner2, and M. Mendillo2 B. S. Lanchester et al.
  • 1University of Southampton, UK
  • 2Center for Space Physics, Boston University, Boston, Massachusetts, USA
  • 3University College London, UK
  • 4Geophysical Institute, University of Alaska, Fairbanks, USA
  • 5Space Sciences Laboratory, University of California, Berkeley, CA, USA

Abstract. Measurements in the visible wavelength range at high spectral resolution (1.3 Å) have been made at Longyearbyen, Svalbard (15.8 E,78.2 N) during an interval of intense proton precipitation. The shape and Doppler shift of hydrogen Balmer beta line profiles have been compared with model line profiles, using as input ion energy spectra from almost coincident passes of the FAST and DMSP spacecraft. The comparison shows that the simulation contains the important physical processes that produce the profiles, and confirms that measured changes in the shape and peak wave-length of the hydrogen profiles are the result of changing energy input. This combination of high resolution measurements with modeling provides a method of estimating the incoming energy and changes in flux of precipitating protons over Svalbard, for given energy and pitch-angle distributions. Whereas for electron precipitation, information on the incident particles is derived from brightness and brightness ratios which require at least two spectral windows, for proton precipitation the Doppler profile of resulting hydrogen emission is directly related to the energy and energy flux of the incident energetic protons and can be used to gather information about the source region. As well as the expected Doppler shift to shorter wavelengths, the measured profiles have a significant red-shifted component, the result of upward flowing emitting hydrogen atoms.

Key words. Ionosphere (auroral ionosphere; particle precipitation) – Magnetospheric physics (auroral phenomena)

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