Auroral energy deposition in the ionospheric F-region studied through ground-based optical tomography
Abstract
Studies of ionospheric perturbations produced by the aurora generally focus on the E-region where the majority of the kinetic energy flux is deposited. However, it is the state of the topside ionosphere that is most critical for mass coupling with the magnetosphere. In this paper, ground-based optical tomography is used to characterize auroral energy deposition in the E- and F-regions simultaneously. The tomographic data are derived using two imaging spectrometers in a 290km baseline near Sondrestrom, Greenland. Vertical profiles of volume emission rate were reconstructed for four prominent auroral emissions: 470.9 nm (N2+ 1NG), 557.7 nm (OI 1S), 630.0 nm (OI 1D), and 844.6 nm (O 3P). The ionospheric response was monitored using the Sondrestrom Incoherent Scatter Radar (ISR). An analysis of a stable auroral arc near the polarward edge of the auroral oval revealed a latitudinally broad region of 844.6 emission at 250km above a narrower region of 470.9 and 557.7 emission. The 844.6 emission is produced by impact of ~11 eV electrons on atomic oxygen, suggesting that the primary electron spectrum had both a high and low energy component. The ISR measurements showed intense F-region ion heating on this flux tube, and a factor-2 increase over the ambient plasma density at 300km, demonstrating that the low energy end of the precipitating particle spectrum can have a significant affect on the topside ionosphere, even in relatively hard auroral arcs.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2004
- Bibcode:
- 2004AGUSMSA43A..01K
- Keywords:
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- 2407 Auroral ionosphere (2704);
- 2494 Instruments and techniques;
- 2736 Magnetosphere/ionosphere interactions