Investigations of the Many Distinct Types of Auroras

Colpitts, C. A.

doi:10.1002/9781118978719.ch1

Cited by 1 publication

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“…The blue‐violet (427.8 nm) auroral emissions are the brightest band generated by ionized molecular nitrogen (

{normalN}_{2}^{+}

). Red (630.0 nm) auroras are the result of a forbidden transition of atomic oxygen (O), detected above 250 km due to collisions of plasma with neutral atmosphere and are not normally visible to the naked eye [ Rees and Luckey , ; Akasofu , ; Colpitts , ]. The red emission line is also associated with patch and blob convection in the high latitudes and is not to be confused with emissions from energetic particle precipitation: airglow emission intensities are much lower than those of the aurora [ Hosokawa et al , ; van der Meeren et al , ].…”

Section: Introductionmentioning

confidence: 99%

High‐latitude GPS phase scintillation from E region electron density gradients during the 20–21 December 2015 geomagnetic storm

et al. 2017

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A novel operating mode for Poker Flat Incoherent Scatter Radar (PFISR) has been developed to support the study of GPS L1 scintillations arising from electron density gradients over Alaska. Previous authors have combined GPS scintillation data with either PFISR or multispectral imagery in this region. This analysis combines all three techniques to determine both gradient parameters as well as the most likely ionospheric source, including a conjunction analysis between GPS signals and known PFISR beams. This approach was used to study scintillation events observed in December 2015. These events were recorded during the recovery phase of a geomagnetic storm that ensued on 20 December when the Earth passed through the path of a solar CME (DST minimum near −170 nT, Kp peak of 7). Two scintillation events were detected through analysis of the phase scintillation index (σϕ), calculated from an Atmospheric and Space Technology Research Associates' Connected Autonomous Space Environment Sensor GPS receiver at Poker Flat. Values of σϕ≃0.5 and σϕ≃1.6 cycles were recorded for these events. Concurrently, an experiment on PFISR was run to discern the electron density along the GPS signal line of site, and the imager observed the 428.7 nm, 557.7 nm, and 630.0 nm emission lines during the experiment window. From the ratios of derived emission intensities, estimates of precipitating particle energies were made allowing confirmation of the altitudes associated with the electron density peaks determined using raw radar returns from PFISR. Results indicate that temporal and spatial electron density gradients existed along the signal's path during periods of highest scintillation, which resulted from impact ionization from auroral particle precipitation at E region altitudes.

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“…The blue‐violet (427.8 nm) auroral emissions are the brightest band generated by ionized molecular nitrogen (