A kinetic perspective on azimuthal variation of magnetopause reconnection at scales below an Earth radius. (September 2020)

• Record Type: Journal Article
• Authors: Zou, Ying; Walsh, Brian M.; Atz, Emil; Liang, Haoming; Ma, Qianli; Angelopoulos, Vassilis
• Is Part Of: Journal of physics. Volume 1620(2020)
• Publication Date: 2020-09
• Subjects: Physics -- Congresses; 530.5
• DOI: 10.1088/1742-6596/1620/1/012028
• Languages: English
• ISSNs: 1742-6588

Abstract

Abstract: Magnetic reconnection efficiency at the Earth's magnetopause has recently been shown to exhibit variations in reconnection jet amplitudes at azimuthal scales below an Earth radius [1]. This finding, however, is obtained based on the bulk velocity moment measurements. If there exists a significant cold magnetospheric ion population in addition to the accelerated magnetosheath population, the combination of the two would yield a low bulk velocity moment that does not necessarily correspond to a weak reconnection activity. Here we analyse ion distribution functions of the three reconnection events in [1] to examine whether the varying jet amplitudes are due to the presence of cold magnetospheric ions or variations of reconnection acceleration. Our results show that, although the cold magnetospheric ions have lowered the absolute bulk velocity, the relative variation trend of the bulk velocity is consistent with that of the acceleration gained by magnetosheath ions. The result supports the interpretation that reconnection activity can vary azimuthally on scales below an Earth radius.