Measurements of Ion‐Neutral Coupling in the Auroral F Region in Response to Increases in Particle Precipitation. Issue 5 (2nd May 2018)

• Record Type: Journal Article
• Authors: Kiene, A.; Bristow, W. A.; Conde, M. G.; Hampton, D. L.
• Is Part Of: Journal of geophysical research. Volume 123:Issue 5(2018)
• Page Start: 3900
• Page End: 3918
• Publication Date: 2018-05-02
• Subjects: Neutral winds -- Ion drifts -- F‐Region -- Ion‐neutral coupling -- Auroral precipitation -- Coupling time scales; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2017JA024999
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: Neutral winds are a key factor in the dynamics of the ionosphere‐thermosphere system. Previous observations have shown that neutral and ion flows are strongly coupled during periods of auroral activity when ion drag forcing can become the dominant force driving neutral wind flow. This is primarily due to increases in ion density due to enhanced particle precipitation as well as associated increases the strength of the electric fields that drive ion motions. Due to this strong coupling, numerical simulations of neutral dynamics have difficulty reproducing neutral wind observations when they are driven by modeled precipitation and modeled convection. It is therefore desirable whenever possible to have concurrent coincident measurements of auroral precipitation and ion convection. Recent advancements in high‐resolution fitting of Super Dual Auroral Radar Network ion convection data have enabled the generation of steady maps of ion drifts over Alaska, coinciding with several optics sites. The Super Dual Auroral Radar Network measurements are compared with scanning Doppler imager neutral wind measurements at similar altitude, providing direct comparisons of ion and neutral velocities over a wide field and for long periods throughout the night. Also present are a digital all‐sky imager and a meridian spectrograph, both of which provide measurements of auroral intensity on several wavelengths. In this study, we combine these data sets to present three case studies that show significant correlation between increases in F region precipitation and enhancements in ion‐neutral coupling in the evening sector. We investigate the time scales over which the coupling takes place and compare our findings to previous measurements. Key Points: Ionospheric momentum coupling responds to local changes in the energy of precipitating particles as well as overall magnetic activity Ion‐neutral coupling forms a front that moves magnetically southward in advance of the visible aurora The time scales over which coupling occurs are analyzed and found to vary in concert with drops in characteristic energy