Distribution of Field‐Aligned Electron Events in the High‐Altitude Polar Region: Cluster Observations. Issue 11 (14th November 2017)

• Record Type: Journal Article
• Authors: Shi, Jiankui; Zhang, Ziying; Torkar, Klaus; Cheng, Zhengwei; Farzakeley, Andrew; Dunlop, Malcolm; Carr, Chris
• Is Part Of: Journal of geophysical research. Volume 122:Issue 11(2017)
• Page Start: 11, 245
• Page End: 11, 255
• Publication Date: 2017-11-14
• Subjects: polar region -- high altitude -- field‐aligned electrons -- spatial distribution -- cluster observation; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2017JA024360
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: Field‐aligned electrons (FAEs) are important for the energy transport in the solar wind‐magnetosphere‐ionosphere coupling. However, the distribution of FAEs and the concerning physical mechanism in different altitudes of the polar region are still unclear. In this paper, data from the Cluster spacecraft were used to study the characteristics of FAEs in high‐altitude polar region. We selected FAE events with a flux higher than 3 × 10 8 (cm 2 s) −1 for our analysis. Their distribution was double peaked around the auroral oval. The main peak occurred around the cusp region (magnetic local time (MLT) 0700–1500) which leaned to the dawnside. The other peak appeared in the evening sector with MLT 2100–2300 just before midnight. The durations of the FAE events covered a wide range from 4 to 475 s, with most of the FAE events lasting less than 40 s. The possible physical mechanisms are discussed, namely, that the downward FAEs may consist of decelerated solar wind and reflected up flowing ionospheric electrons in the potential drops, whereas the upward ones may be mirrored solar wind electrons and accelerated ionospheric up flowing electrons. Key Points: Cluster FAE distribution is double peaked around auroral oval at high altitude The distribution shows a dawn favored asymmetry in the cusp/cleft region The FAE durations can be 475 s which is the longest of the so far observed