Bibliography

A case study of isolated auroral spots based on DMSP data

This study employed ultraviolet images and particle data to investigate isolated auroral spots away from the Earth\textquoterights auroral oval. Data from SSUSI (Special Sensor Ultraviolet Spectrographic Imager) and SSJ (Special Sensor J) mounted on the DMSP (Defence Meteorological Satellite Program) spacecraft were examined. The isolated auroral spots were observed by DMSP F16/SSUSI and F17/SSUSI on 29 May 2010 during the recovery phase of a moderate geomagnetic storm with a minimum SYM-H index of -70 nT. The auroral spots were observed between 18:00\textendash21:00 MLT and corotated with the Earth, but stayed almost at the same magnetic latitude (MLAT) of -60\textdegree. It is found that the isolated auroral spots were produced mainly by energetic ring current ions at energies above ~10\ keV. The enhancement in the electron flux with energy below ~200\ eV was also observed for the isolated auroral spots. The MLAT of the electron flux was nearly 2\textdegreehigher than that for the precipitating ions.

Zhou, Su; Chen, Yuqing; Zhang, Jin;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on: 01/2020

YEAR: 2020     DOI: 10.1016/j.jastp.2019.105176

Isolated auroral spots; Proton aurora; Subauroral electron precipitation

Proton aurora observed from the ground

Auroral keV proton precipitation is a significant-energy particle input upon the high-latitude ionosphere, often dominating in the polar cusp and the dusk sector of the equatorward auroral oval. A unique signature of proton precipitation is the Doppler-shifted H Balmer lines (Hα, Hβ) observable from the ground. These lines are emitted by energetic H atoms produced within the proton beam through charge-exchange processes. Their observations allow one to assess the location, dynamic evolution especially during magnetospheric substorms, and spectral characteristics of the source regions of the energetic protons projected to the high-latitude ionosphere. They also allow to identify the associated magnetospheric processes and to evaluate ionospheric perturbations induced by the energetic protons. The source regions include the cusp, the low-latitude boundary layer, the mantle, and the plasma sheet, including its dayside extension. If qualitative studies of proton aurora morphology and time variability are possible with photometric observations of hydrogen lines, quantitative assessment of H-emission brightness, and incident proton mean energy and flux, requires spectroscopic measurements of the H-emission profile. In this review paper, we report on the tremendous progress made in the past 20 years in the observational capability applied to proton aurora and in the modeling of energetic proton transport in the upper atmosphere, which is needed for quantitative analysis of the spectroscopic measurements of H emission. The current issues in the field are also discussed and suggestions for future directions are proposed. They include the deployment of chains of instruments dedicated to proton aurora studies along magnetic local time and geomagnetic latitude, such as high-spectral-resolution-imaging spectrographs and spectral imagers. Such campaigns would improve our understanding of the topology and dynamics of the magnetosphere, and provide, at dayside, the azimuthal extent of the reconnection region. Magnetically conjugate experiments and optical instruments dedicated to proton aurora observations in Antarctica are greatly encouraged. The contribution of atmospheric scattering to the H-spectral profiles needs to be further assessed and additional laboratory measurements of differential cross sections are required for a comprehensive understanding of the physics of proton aurora.

Galand, Marina; Chakrabarti, Supriya;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on:

YEAR: 2006     DOI: https://doi.org/10.1016/j.jastp.2005.04.013

Proton aurora; H. Balmer; Auroral spectroscopy

Quantification of the spreading effect of auroral proton precipitation

A three-dimensional Monte Carlo model has been developed to study the transverse beam spreading effect of incident energetic auroral protons during their precipitation in the Earth\textquoterights upper atmosphere. Energetic protons with an isotropic angular distribution are injected at 700 km altitude. Two types of incident energy spectra, a monoenergetic and a Maxwellian distribution, are considered. Interaction of fast particles with a three-species atmosphere (O, N₂, and O₂) is included through charge exchange, electron stripping, ionization, excitation, and elastic scattering collisions. A uniform geomagnetic field is assumed in the model. The spreading effect is simulated for both a fine proton beam and a proton arc of longitudinal and latitudinal extent. It is found that the main dispersion region for a fine proton beam is located in the altitude range of around 250\textendash450 km, where the first few charge exchange collisions play a significant role. In the spreading study for a proton arc, we compare the numerical results with previous studies and give a convincing explanation by analyzing atmospheric scale heights and cross-section data. For the purpose of the model validity check, we make a comparison of the Monte Carlo simulation with observations and the results from other models.

Fang, Xiaohua; Liemohn, Michael; Kozyra, Janet; Solomon, Stanley;

Published by: Journal of Geophysical Research: Space Physics (1978\textendash2012)      Published on:

YEAR: 2004     DOI: 10.1029/2003JA010119

Monte Carlo simulation; Proton aurora