Journal cover Journal topic
Annales Geophysicae An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 1.585 IF 1.585
  • IF 5-year value: 1.698 IF 5-year
    1.698
  • CiteScore value: 1.62 CiteScore
    1.62
  • SNIP value: 0.820 SNIP 0.820
  • IPP value: 1.52 IPP 1.52
  • SJR value: 0.781 SJR 0.781
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 83 Scimago H
    index 83
  • h5-index value: 24 h5-index 24
Volume 23, issue 5
Ann. Geophys., 23, 1623–1635, 2005
https://doi.org/10.5194/angeo-23-1623-2005
© Author(s) 2005. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue: Atmospheric studies by optical methods

Ann. Geophys., 23, 1623–1635, 2005
https://doi.org/10.5194/angeo-23-1623-2005
© Author(s) 2005. This work is distributed under
the Creative Commons Attribution 3.0 License.

  27 Jul 2005

27 Jul 2005

Variations of auroral hydrogen emission near substorm onset

L. P. Borovkov, B. V. Kozelov, L. S. Yevlashin, and S. A. Chernouss L. P. Borovkov et al.
  • Polar Geophysical Institute, Apatity, Murmansk region, 184209 Russia

Abstract. The results of coordinated optical ground-based observations of the auroral substorm on 26 March 2004 in the Kola Peninsula are described. Imaging spectrograph data with high spectral and temporal resolution recorded the Doppler profile of the Hα hydrogen emission; this allows us to estimate the average energy of precipitating protons and the emission intensity of the hydrogen Balmer line. Two different populations of precipitating protons were observed during an auroral substorm. The first of these is associated with a diffuse hydrogen emission that is usually observed in the evening sector of the auroral oval and located equatorward of the discrete electron arcs associated with substorm onset. The average energy of the protons during this precipitation was ~20–35 keV, and the energy flux was ~3x10–4Joule/m2s. The second proton population was observed 1–2min after the breakup during 4–5min of the expansion phase of substorm into the zone of bright, discrete auroral structures (N-S arcs). The average energy of the protons in this population was ~60 keV, and the energy flux was ~2.2x10–3Joule/m2s. The observed spatial structure of hydrogen emission is additional evidence of the higher energy of precipitated protons in the second population, relative to the protons in the diffuse aurora. We believe that the most probable mechanism of precipitation of the second population protons was pitch-angle scattering of particles due to non-adiabatic motion in the region of local dipolarization near the equatorial plane.

Keywords. Auroral ionosphere; Particle precipitation; Storms and substorms

Publications Copernicus
Download
Citation