Distributions of Birkeland current density observed by AMPERE are heavy-tailed or long-tailed

Coxon, John, Chisham, Gareth, Freeman, Mervyn P., Anderson, Brian J. and Fear, Robert C. (2022) Distributions of Birkeland current density observed by AMPERE are heavy-tailed or long-tailed. Journal of Geophysical Research: Space Physics, 127 (2). e2021JA029801. ISSN 2169-9380

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Official URL: https://doi.org/10.1029/2021JA029801

Abstract

Abstract We analyze probability distributions of Birkeland current densities measured by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE). We find that the distributions are leptokurtic rather than normal and they are sometimes heavy-tailed. We fit q-exponential functions to the distributions and use these to estimate where the largest currents are likely to occur. The shape and scale parameters of the fitted q-exponential distribution vary with location: The scale parameter maximises for current densities with the same polarity and in the same location as the average Region 1 current, whereas the shape parameter maximises for current densities with the same polarity and in the same location as the average Region 2 current. We find that current densities |J|≥ 0.2 μA m−2 are most likely to occur in the average Region 1 current region, and second most likely to occur in the average Region 2 current region. However, for extreme currents (|J|≥ 4.0 μA m−2), we find that the most likely location is colocated with the average Region 2 current region on the dayside, at a colatitude of 18° − 22°.

Item Type: Article
Additional Information: Funding information: J.C. Coxon was supported by Science and Technology Facilities Council (STFC) Ernest Rutherford Fellowship ST/V004883/1 and Consolidated Grant ST/R000719/1. G. Chisham and M.P. Freeman were supported by the British Antarctic Survey (BAS) Polar Science for Planet Earth Programme, as funded by the UK Natural Environment Research Council (NERC), as part of United Kingdom Research and Innovation (UKRI).
Uncontrolled Keywords: birkeland currents, q-exponential, distributions, tsallis statistics, field-aligned currents, space weather
Subjects: F300 Physics
F500 Astronomy
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Elena Carlaw
Date Deposited: 25 Jan 2022 17:06
Last Modified: 31 Jan 2022 10:30
URI: http://nrl.northumbria.ac.uk/id/eprint/48250

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