Occurrence and average behavior of pulsating aurora. Issue 5 (11th May 2017)

• Record Type: Journal Article
• Authors: Partamies, N.; Whiter, D.; Kadokura, A.; Kauristie, K.; Nesse Tyssøy, H.; Massetti, S.; Stauning, P.; Raita, T.
• Is Part Of: Journal of geophysical research. Volume 122:Issue 5(2017)
• Page Start: 5606
• Page End: 5618
• Publication Date: 2017-05-11
• Subjects: pulsating aurora -- emission height; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2017JA024039
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: Motivated by recent event studies and modeling efforts on pulsating aurora, which conclude that the precipitation energy during these events is high enough to cause significant chemical changes in the mesosphere, this study looks for the bulk behavior of auroral pulsations. Based on about 400 pulsating aurora events, we outline the typical duration, geomagnetic conditions, and change in the peak emission height for the events. We show that the auroral peak emission height for both green and blue emission decreases by about 8 km at the start of the pulsating aurora interval. This brings the hardest 10% of the electrons down to about 90 km altitude. The median duration of pulsating aurora is about 1.4 h. This value is a conservative estimate since in many cases the end of event is limited by the end of auroral imaging for the night or the aurora drifting out of the camera field of view. The longest durations of auroral pulsations are observed during events which start within the substorm recovery phases. As a result, the geomagnetic indices are not able to describe pulsating aurora. Simultaneous Antarctic auroral images were found for 10 pulsating aurora events. In eight cases auroral pulsations were seen in the southern hemispheric data as well, suggesting an equatorial precipitation source and a frequent interhemispheric occurrence. The long lifetimes of pulsating aurora, their interhemispheric occurrence, and the relatively high‐precipitation energies make this type of aurora an effective energy deposition process which is easy to identify from the ground‐based image data. Key Points: Statistical study of 400 periods of pulsating aurora has been conducted Auroral peak emission height decreases about 8 km at the start of a pulsating aurora event Majority of the events include pulsating aurora on both hemispheres