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Greenwald et al. 2002
Greenwald, R.A., Shepherd, S.G., Sotirelis, T.S., Ruohoniemi, J.M. and Barnes, R.J. (2002). Dawn and dusk sector comparisons of small-scale irregularities, convection, and particle precipitation in the high-latitude ionosphere. Journal of Geophysical Research 107: doi: 10.1029/2001JA000158. issn: 0148-0227.

Small-scale ionospheric irregularities and auroral precipitation are common features of the auroral ionosphere, but their spatial association has not been examined on global scales. In this paper, we compare electron and ion precipitation from individual passes of the Defense Meteorological Satellite Program (DMSP) spacecraft with concurrent observations of ionospheric irregularities and plasma convection from the Northern Hemisphere component of the Super Dual Auroral Radar Network (SuperDARN). Because of the nature of the DMSP orbits and the spatial resolution of the SuperDARN measurements these comparisons have been limited to the dusk and postdawn sectors and spatial dimensions greater than ~100 km. We have found that the SuperDARN radars generally observe ionospheric irregularities over a greater latitudinal extent than the DMSP satellites observe particle precipitation. Specifically, ionospheric irregularities are observed both equatorward and poleward of the convection reversal boundary (CRB) in the dawn and dusk sectors, whereas particle precipitation is only observed equatorward of the CRB. Under conditions where the radars can detect the true equatorward boundary of the irregularities, they are observed to extend equatorward of the particle precipitation. Both irregularities and particle precipitation expand equatorward with increasing geomagnetic activity, and there is evidence that precipitation regions with higher energy flux are associated with regions of stronger sunward convection. These results suggest that SuperDARN can provide a coarse determination of the auroral-oval position that will complement measurements with optics and particle detectors. More importantly, they demonstrate the spatial relationships between precipitation, electric fields, and ionospheric irregularities that result from the electrical coupling between the magnetosphere and ionosphere and the dependence of ionospheric plasma instabilities on the ionospheric electric field and precipitation-induced electron-density gradients.

BACKGROUND DATA FILES

Abstract

Keywords
Magnetospheric Physics, Plasma convection, Ionosphere, Auroral ionosphere, Ionosphere, Plasma convection, Ionosphere, Particle precipitation, Ionosphere, Ionospheric irregularities
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
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