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Title: Van Allen Probes observations of electromagnetic ion cyclotron waves triggered by enhanced solar wind dynamic pressure

Abstract

Magnetospheric compression due to impact of enhanced solar wind dynamic pressure P dyn has long been considered as one of the generation mechanisms of electromagnetic ion cyclotron (EMIC) waves. Here, with the Van Allen Probe-A observations, we identify three EMIC wave events that are triggered by P dyn enhancements under prolonged northward interplanetary magnetic field (IMF) quiet time preconditions. They are in contrast to one another in a few aspects. Event 1 occurs in the middle of continuously increasing P dyn while Van Allen Probe-A is located outside the plasmapause at postmidnight and near the equator (magnetic latitude (MLAT) ~ -3°). Event 2 occurs by a sharp P dyn pulse impact while Van Allen Probe-A is located inside the plasmapause in the dawn sector and rather away from the equator (MLAT ~ 12°). Event 3 is characterized by amplification of a preexisting EMIC wave by a sharp P dyn pulse impact while Van Allen Probe-A is located outside the plasmapause at noon and rather away from the equator (MLAT ~ -15°). These three events represent various situations where EMIC waves can be triggered by P dyn increases. Several common features are also found among the three events. (i) The strongestmore » wave is found just above the He + gyrofrequency. (ii) The waves are nearly linearly polarized with a rather oblique propagation direction (~28° to ~39° on average). (iii) The proton fluxes increase in immediate response to the P dyn impact, most significantly in tens of keV energy, corresponding to the proton resonant energy. (iv) The temperature anisotropy with T > T || is seen in the resonant energy for all the events, although its increase by the P dyn impact is not necessarily always significant. Finally, the last two points (iii) and (iv) may imply that in addition to the temperature anisotropy, the increase of the resonant protons must have played a critical role in triggering the EMIC waves by the enhanced P dyn impact.« less

Authors:
 [1];  [1];  [1];  [1];  [2];  [3];  [2];  [1];  [4];  [5]
  1. Chungbuk National Univ., Cheongju (Korea, Republic of). Dept. of Astronomy and Space Science
  2. Korea Astronomy and Space Science Inst., Daejeon (Korea, Republic of)
  3. Daegu Univ., Gyeongsan (Korea, Republic of). Dept. of Earth Science Education
  4. Univ. of Minnesota, Minneapolis, MN (United States). School of Physics and Astronomy
  5. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chungbuk National Univ., Cheongju (Korea, Republic of); Korea Astronomy and Space Science Inst., Daejeon (Korea, Republic of)
Sponsoring Org.:
USDOE; Ministry of Science, ICT and Future Planning (MSIP) of Korea
OSTI Identifier:
1477694
Report Number(s):
LA-UR-17-28134
Journal ID: ISSN 2169-9380
Grant/Contract Number:  
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Space Physics
Additional Journal Information:
Journal Volume: 121; Journal Issue: 10; Journal ID: ISSN 2169-9380
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; EMIC waves; dynamic pressure; Van Allen Probes

Citation Formats

Cho, J. -H., Lee, D. -Y., Noh, S. -J., Shin, D. -K., Hwang, J., Kim, K. -C., Lee, J. J., Choi, C. R., Thaller, S., and Skoug, R. Van Allen Probes observations of electromagnetic ion cyclotron waves triggered by enhanced solar wind dynamic pressure. United States: N. p., 2016. Web. doi:10.1002/2016JA022841.
Cho, J. -H., Lee, D. -Y., Noh, S. -J., Shin, D. -K., Hwang, J., Kim, K. -C., Lee, J. J., Choi, C. R., Thaller, S., & Skoug, R. Van Allen Probes observations of electromagnetic ion cyclotron waves triggered by enhanced solar wind dynamic pressure. United States. doi:10.1002/2016JA022841.
Cho, J. -H., Lee, D. -Y., Noh, S. -J., Shin, D. -K., Hwang, J., Kim, K. -C., Lee, J. J., Choi, C. R., Thaller, S., and Skoug, R. Fri . "Van Allen Probes observations of electromagnetic ion cyclotron waves triggered by enhanced solar wind dynamic pressure". United States. doi:10.1002/2016JA022841. https://www.osti.gov/servlets/purl/1477694.
@article{osti_1477694,
title = {Van Allen Probes observations of electromagnetic ion cyclotron waves triggered by enhanced solar wind dynamic pressure},
author = {Cho, J. -H. and Lee, D. -Y. and Noh, S. -J. and Shin, D. -K. and Hwang, J. and Kim, K. -C. and Lee, J. J. and Choi, C. R. and Thaller, S. and Skoug, R.},
abstractNote = {Magnetospheric compression due to impact of enhanced solar wind dynamic pressure Pdyn has long been considered as one of the generation mechanisms of electromagnetic ion cyclotron (EMIC) waves. Here, with the Van Allen Probe-A observations, we identify three EMIC wave events that are triggered by Pdyn enhancements under prolonged northward interplanetary magnetic field (IMF) quiet time preconditions. They are in contrast to one another in a few aspects. Event 1 occurs in the middle of continuously increasing Pdyn while Van Allen Probe-A is located outside the plasmapause at postmidnight and near the equator (magnetic latitude (MLAT) ~ -3°). Event 2 occurs by a sharp Pdyn pulse impact while Van Allen Probe-A is located inside the plasmapause in the dawn sector and rather away from the equator (MLAT ~ 12°). Event 3 is characterized by amplification of a preexisting EMIC wave by a sharp Pdyn pulse impact while Van Allen Probe-A is located outside the plasmapause at noon and rather away from the equator (MLAT ~ -15°). These three events represent various situations where EMIC waves can be triggered by Pdyn increases. Several common features are also found among the three events. (i) The strongest wave is found just above the He+ gyrofrequency. (ii) The waves are nearly linearly polarized with a rather oblique propagation direction (~28° to ~39° on average). (iii) The proton fluxes increase in immediate response to the Pdyn impact, most significantly in tens of keV energy, corresponding to the proton resonant energy. (iv) The temperature anisotropy with T⊥ > T|| is seen in the resonant energy for all the events, although its increase by the Pdyn impact is not necessarily always significant. Finally, the last two points (iii) and (iv) may imply that in addition to the temperature anisotropy, the increase of the resonant protons must have played a critical role in triggering the EMIC waves by the enhanced Pdyn impact.},
doi = {10.1002/2016JA022841},
journal = {Journal of Geophysical Research. Space Physics},
issn = {2169-9380},
number = 10,
volume = 121,
place = {United States},
year = {2016},
month = {9}
}

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