Statistical Characterization of Stormtime Ionospheric Redistribution At Mid-Latitudes
Abstract
During major geomagnetic disturbances, dramatic redistribution of ionospheric plasma can occur in the mid-latitude plasmasphere boundary layer, driven by a complex set of interlocked dynamics involving photoionization, magnetospheric influence, ionospheric feedback mechanisms, and the background magnetic field direction. Large amounts of ionospheric material are seen to stream from the dusk sector sunward to the polar cap cusp region, as mesoscale plumes of storm enhanced density (SED) move under the influence of the sub-auroral polarization stream (SAPS) electric field in regions magnetically linked to the region 2 currents associated with the asymmetric ring current. Studies over the last decade have shown that these several degree wide SAPS flow channels, with sunward fluxes delivering over 1E14 ions/m^2/sec to the noontime cusp, are the signatures of processes which can deplete an entire L shell of plasmaspheric material in one hours' time for particularly intense storms. Ground based ionospheric radar measurements of these features lend considerable insight into magnetosphere-ionosphere coupling processes and dynamics. We discuss a statistical study of SAPS/SED region sunward ionospheric flux in the dusk magnetic local time sector using a database of over 1000 Millstone Hill ionospheric radar scans during Kp >= 3 disturbances from 1979-2001. We highlight several persistent features of ionospheric F region velocity and SAPS ion flux magnitude. In particular, sunward F region ion flux is relatively insensitive to magnetic local time and the passage of the dusk solar terminator. Potential explanations focus on the interplay between poleward perpendicular electric field and ionospheric height-integrated Pedersen conductance in the E and F regions as the thermosphere and ionosphere change state from day to night.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFMSM22A..03E
- Keywords:
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- 2431 IONOSPHERE / Ionosphere/magnetosphere interactions;
- 2441 IONOSPHERE / Ionospheric storms;
- 2443 IONOSPHERE / Midlatitude ionosphere;
- 2736 MAGNETOSPHERIC PHYSICS / Magnetosphere/ionosphere interactions