PFSIR observations of equatorward-expanding ionospheric F-region patch and its association with the flow and auroral activities
Abstract
We present an event study with conjunctive THEMIS and PFISR observations on March 3, 2009, 10-12 UT. During this event interval mid-tail probe THEMIS-C detected a series of fast earthward flows. Correspondingly, ground-based optical observations revealed strong red-line (630nm) emission intensifications and equatorward-moving auroral structures, but they were not accompanied by a substorm expansion. Using the Poker Flat incoherent radar (PFISR) observations we are able to fully explore the 4-D (time, latitude, longitude, and altitude) properties of the ionospheric electron density profile for this event. We found that localized density enhancements (patches) appeared with the start of the flow and auroral activities, and then expanded progressively equatorward. The patches were limited within roughly the same latitudinal/latitudinal range of a moving auroral arc, and existed dominantly in F-region (~150-300 km), suggesting that the precipitating particles generating the patches were relatively soft in energy (<1keV), similar to that responsible for the red-line auroral emissions. More interestingly, when the patches extended further equatorward they were substantially elevated in altitudes. Synthesizing all observations we discuss the possible particle sources and mechanisms, both magnetospheric and ionospheric, that lead to the of the observed F-region patch dynamics.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFMSM53D..08L
- Keywords:
-
- 2427 IONOSPHERE / Ionosphere/atmosphere interactions;
- 2431 IONOSPHERE / Ionosphere/magnetosphere interactions;
- 2704 MAGNETOSPHERIC PHYSICS / Auroral phenomena