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Ring current morphology from MMS observations
  • +5
  • Xin Tan,
  • Malcolm W Dunlop,
  • XiangCheng Dong,
  • Yanyan Yang,
  • Yingshuai Du,
  • Chao Shen,
  • Christopher T. Russell,
  • Wenlong Liu
Xin Tan
Beihang University
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Malcolm W Dunlop
Beihang University

Corresponding Author:[email protected]

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XiangCheng Dong
Yunnan University
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Yanyan Yang
National Institute of Natural Hazards, Ministry of Emergency Management of China (former Institute of Crustal Dynamic, China Earthquake Administration)
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Yingshuai Du
Beihang University
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Chao Shen
School of Science, Harbin Institute of Technology
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Christopher T. Russell
University of California Los Angeles
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Wenlong Liu
Beihang University
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Abstract

We directly estimate the in situ current density of the Earth’s ring current (RC) using the curlometer method and investigate its morphology using the small spatial separations and high accuracy of the Magnetospheric Multiscale mission (MMS). Through statistical analysis of data from September 2015 to the end of 2016, covering the region of 2-8 RE (Earth radius, 6371 km), we reveal an almost complete near-equatorial (within ) RC morphology in terms of radial distance and local time (MLT) which complements and extends that found from previous studies. We found no evidence of RC enhancement on the dusk-side during geomagnetic active periods, but details of local time (MLT) asymmetries in, and the boundary between, the inner (eastward) and outer (westward) currents are revealed. We propose that part of the asymmetry demonstrated here suggests that in addition to the overall persistence of the westward RC, two large banana-like currents are directly observed, one which could arise from a peak of plasma pressure near ~4.8 RE on the noon side and the other from a valley of plasma pressure which could arise near ~4.8 RE on the night side.