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The Spatial Distribution of Charge Exchange Loss Contributions to Storm Time Ring Current Decay: Van Allen Probes Observations
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  • Songyan Li,
  • Hao Luo,
  • Yasong S Ge,
  • Aimin Du,
  • Elena A. Kronberg,
  • Can Huang,
  • Ying Zhang,
  • Gengxiong Chen
Songyan Li
Institute of Geology and Geophysics, Chinese Academy of Sciences
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Hao Luo
Institute of Geology and Geophysics, Chinese Academy of Sciences

Corresponding Author:[email protected]

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Yasong S Ge
Institute of Geology and Geophysics
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Aimin Du
Institue of Geology and Geophysics, Chinese Academy of Sciences
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Elena A. Kronberg
Ludwig Maximilian University of Munich
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Can Huang
Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences
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Ying Zhang
INSTITUTE OF GEOLOGY AND GEOPHYSICS CHINESE ACADEMY OF SCIENCES (IGGCAS)
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Gengxiong Chen
Institute of Geology and Geophysics, Chinese Academy of Sciences
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Abstract

Charge exchange between hot ions and cold neutral atoms is an important effect in ring current loss processes on magnetized planets. In this letter, we investigate the spatial distribution of charge exchange loss contributions to terrestrial ring current decay using data from the Van Allen Probes. These contributions were calculated by dividing local energetic neutral atom energy density escape rates by local ring current energy density decay rates. The results exhibit clear MLT and L dependence, with larger contributions observed nightside during the recovery phase of geomagnetic storms. The contribution of H+; peaked at L~4 during early recovery phases and was stronger at higher L shells during late recovery phases, while O+; decreased slightly with L shell. Possible explanations for this inhomogeneous distribution are also discussed. The asymmetric exospheric hydrogen density distribution may cause the inhomogeneous distribution in the MLT, while the L dependence may be related to the charge exchange cross-section and the ion energy flux. These results provide the first spatial distribution of charge exchange contributions, which is helpful for understanding local terrestrial ring current evolution.