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Variations in energy, flux, and brightness of pulsating aurora measured at high time resolution
KTH, School of Electrical Engineering (EES), Space and Plasma Physics. KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.ORCID iD: 0000-0001-5596-346X
KTH, School of Electrical Engineering (EES), Space and Plasma Physics. KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.ORCID iD: 0000-0003-2422-5426
2017 (English)In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 35, no 3, p. 493-503Article in journal (Refereed) Published
Abstract [en]

High-resolution multispectral optical and incoherent scatter radar data are used to study the variability of pulsating aurora. Two events have been analysed, and the data combined with electron transport and ion chemistry modelling provide estimates of the energy and energy flux during both the ON and OFF periods of the pulsations. Both the energy and energy flux are found to be reduced during each OFF period compared with the ON period, and the estimates indicate that it is the number flux of foremost higher-energy electrons that is reduced. The energies are found never to drop below a few kilo-electronvolts during the OFF periods for these events. The high-resolution optical data show the occurrence of dips in brightness below the diffuse background level immediately after the ON period has ended. Each dip lasts for about a second, with a reduction in brightness of up to 70% before the intensity increases to a steady background level again. A different kind of variation is also detected in the OFF period emissions during the second event, where a slower decrease in the background diffuse emission is seen with its brightness minimum just before the ON period, for a series of pulsations. Since the dips in the emission level during OFF are dependent on the switching between ON and OFF, this could indicate a common mechanism for the precipitation during the ON and OFF phases. A statistical analysis of brightness rise, fall, and ON times for the pulsations is also performed. It is found that the pulsations are often asymmetric, with either a slower increase of brightness or a slower fall.

Place, publisher, year, edition, pages
COPERNICUS GESELLSCHAFT MBH , 2017. Vol. 35, no 3, p. 493-503
Keywords [en]
Ionosphere (auroral ionosphere, particle precipitation), magnetospheric physics (magnetosphere-ionosphere-interactions)
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
URN: urn:nbn:se:kth:diva-205451DOI: 10.5194/angeo-35-493-2017ISI: 000398189900001Scopus ID: 2-s2.0-85016499071OAI: oai:DiVA.org:kth-205451DiVA, id: diva2:1098555
Note

QC 20170524

Available from: 2017-05-24 Created: 2017-05-24 Last updated: 2017-11-13Bibliographically approved

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Dahlgren, HannaIvchenko, Nickolay

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