Statistical altitude distribution of the auroral density cavity
2015 (English)In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 120, no 2, 996-1006 p.Article in journal (Refereed) Published
The statistical altitude distribution of auroral density cavities located between 3.0 and 6.5 R-E is investigated using in situ observations from flux tubes exhibiting auroral acceleration. The locations of the observations are described using a pseudo altitude derived from the distribution of the parallel potential drop above and below the satellite. The upper edge of the auroral acceleration region is observed between 4.375 and 5.625 R-E. Above 6.125 R-E, none of the events exhibit precipitating inverted V electrons, though the upward ion beam can be observed. This indicates that the satellites are located inside the same flux tube as, but above, the auroral acceleration region. The electron density decreases as we move higher into the acceleration region. The spacecraft potential continues to decrease once above the acceleration region, indicating that the density cavity extends above the acceleration region. From 3.0 to 4.375 R-E the pseudo altitude increases by 0.20 per R-E, consistent with a distributed parallel electric field. Between 4.375 and 5.625 R-E the pseudo altitude increases weakly, by 0.01 per R-E, due to an increasing number of events per altitude bin, which are occurring above the acceleration region. Above 5.625 R-E the pseudo altitude increases by 0.28 per R-E, due to a rapid increase in the number of events per altitude bin occurring above the acceleration region, indicating that the remaining parallel potential drop is concentrated in a narrow region at the upper edge of the acceleration region, rather than in a distributed parallel electric field.
Place, publisher, year, edition, pages
2015. Vol. 120, no 2, 996-1006 p.
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:kth:diva-155704DOI: 10.1002/2014JA020691ISI: 000351360800011ScopusID: 2-s2.0-84924811630OAI: oai:DiVA.org:kth-155704DiVA: diva2:761995
Updated from "Manuscript" to "Article". QC 201504202014-11-102014-11-102015-11-02Bibliographically approved