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Title: Energization of the Ring Current by Substorms

Abstract

The substorm process releases large amounts of energy into the magnetospheric system, although where the energy is transferred to and how it is partitioned remains an open question. In this study, we address whether the substorm process contributes a significant amount of energy to the ring current. The ring current is a highly variable region, and understanding the energization processes provides valuable insight into how substorm-ring current coupling may contribute to the generation of storm conditions and provide a source of energy for wave driving. In order to quantify the energy input into the ring current during the substorm process, we analyze Radiation Belt Storm Probes Ion Composition Experiment and Helium Oxygen Proton Electron ion flux measurements for H +, O +, and He +. The energy content of the ring current is estimated and binned spatially for L and magnetic local time. The results are combined with an independently derived substorm event list to perform a statistical analysis of variations in the ring current energy content with substorm phase. We show that the ring current energy is significantly higher in the expansion phase compared to the growth phase, with the energy enhancement persisting into the substorm recovery phase. Themore » characteristics of the energy enhancement suggest the injection of energized ions from the tail plasma sheet following substorm onset. The local time variations indicate a loss of energetic H + ions in the afternoon sector, likely due to wave-particle interactions. Overall, we find that the average energy input into the ring current is ~9% of the previously reported energy released during substorms.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [5]; ORCiD logo [6]; ORCiD logo [6]
  1. Univ. College London (United Kingdom). Dept. of Space and Climate Physics. Mullard Space Science Lab.
  2. British Antarctic Survey, Cambridge (United Kingdom)
  3. Johns Hopkins Univ., Baltimore, MD (United States). Applied Physics Lab.
  4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  5. Univ. of New Hampshire, Durham, NH (United States). Inst. for the Study of Earth, Oceans, and Space
  6. Univ. of Southampton (United Kingdom). Dept. of Physics and Astronomy
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE; National Aeronautic and Space Administration (NASA); Science and Technology Facilities Council (STFC) (United Kingdom); Natural Environment Research Council (NERC) (United Kingdom)
OSTI Identifier:
1484669
Report Number(s):
LA-UR-18-28975
Journal ID: ISSN 2169-9380
Grant/Contract Number:  
89233218CNA000001; NNN06AA01C; NAS5-01072; ST/N0007722/1; NE/L007495/1; NE/N014480/1; NE/L007177/1
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Space Physics
Additional Journal Information:
Journal Volume: 123; Journal Issue: 10; Journal ID: ISSN 2169-9380
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; Heliospheric and Magnetospheric Physics

Citation Formats

Sandhu, J. K., Rae, I. J., Freeman, M. P., Forsyth, C., Gkioulidou, M., Reeves, G. D., Spence, H. E., Jackman, C. M., and Lam, M. M. Energization of the Ring Current by Substorms. United States: N. p., 2018. Web. doi:10.1029/2018JA025766.
Sandhu, J. K., Rae, I. J., Freeman, M. P., Forsyth, C., Gkioulidou, M., Reeves, G. D., Spence, H. E., Jackman, C. M., & Lam, M. M. Energization of the Ring Current by Substorms. United States. doi:10.1029/2018JA025766.
Sandhu, J. K., Rae, I. J., Freeman, M. P., Forsyth, C., Gkioulidou, M., Reeves, G. D., Spence, H. E., Jackman, C. M., and Lam, M. M. Mon . "Energization of the Ring Current by Substorms". United States. doi:10.1029/2018JA025766. https://www.osti.gov/servlets/purl/1484669.
@article{osti_1484669,
title = {Energization of the Ring Current by Substorms},
author = {Sandhu, J. K. and Rae, I. J. and Freeman, M. P. and Forsyth, C. and Gkioulidou, M. and Reeves, G. D. and Spence, H. E. and Jackman, C. M. and Lam, M. M.},
abstractNote = {The substorm process releases large amounts of energy into the magnetospheric system, although where the energy is transferred to and how it is partitioned remains an open question. In this study, we address whether the substorm process contributes a significant amount of energy to the ring current. The ring current is a highly variable region, and understanding the energization processes provides valuable insight into how substorm-ring current coupling may contribute to the generation of storm conditions and provide a source of energy for wave driving. In order to quantify the energy input into the ring current during the substorm process, we analyze Radiation Belt Storm Probes Ion Composition Experiment and Helium Oxygen Proton Electron ion flux measurements for H+, O+, and He+. The energy content of the ring current is estimated and binned spatially for L and magnetic local time. The results are combined with an independently derived substorm event list to perform a statistical analysis of variations in the ring current energy content with substorm phase. We show that the ring current energy is significantly higher in the expansion phase compared to the growth phase, with the energy enhancement persisting into the substorm recovery phase. The characteristics of the energy enhancement suggest the injection of energized ions from the tail plasma sheet following substorm onset. The local time variations indicate a loss of energetic H+ ions in the afternoon sector, likely due to wave-particle interactions. Overall, we find that the average energy input into the ring current is ~9% of the previously reported energy released during substorms.},
doi = {10.1029/2018JA025766},
journal = {Journal of Geophysical Research. Space Physics},
number = 10,
volume = 123,
place = {United States},
year = {2018},
month = {9}
}

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