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Filters: Author is Woodger, Leslie  [Clear All Filters]
2019
Authors: Lessard Marc R., Paulson Kristoff, Spence Harlan E., Weaver Carol, Engebretson Mark J, et al.
Title: Generation of EMIC Waves and Effects on Particle Precipitation During a Solar Wind Pressure Intensification with B z >
Abstract: During geomagnetic storms, some fraction of the solar wind energy is coupled via reconnection at the dayside magnetopause, a process that requires a southward interplanetary magnetic field Bz. Through a complex sequence of events, some of this energy ultimately drives the generation of electromagnetic ion cyclotron (EMIC) waves, which can then scatter energetic electrons and ions from the radiation belts. In the event described in this paper, the interplanetary magnetic field remained northward throughout the event, a condition unfavorable for solar wind energy coupling through low‐latitude reconnection. While this resulted in SYM/H remaining positive throughout the event (so this may not be considered a storm, in spite of the very high solar wind densities), pressure fluctuations were d. . .
Date: 05/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2019JA026477 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA026477
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Authors: Qin Murong, Hudson Mary, Li Zhao, Millan Robyn, Shen Xiaochen, et al.
Title: Investigating Loss of Relativistic Electrons Associated With EMIC Waves at Low L Values on 22 June 2015
Abstract: In this study, rapid loss of relativistic radiation belt electrons at low L* values (2.4–3.2) during a strong geomagnetic storm on 22 June 2015 is investigated along with five possible loss mechanisms. Both the particle and wave data are obtained from the Van Allen Probes. Duskside H+ band electromagnetic ion cyclotron (EMIC) waves were observed during a rapid decrease of relativistic electrons with energy above 5.2 MeV occurring outside the plasmasphere during extreme magnetopause compression. Lower He+ composition and enriched O+ composition are found compared to typical values assumed in other studies of cyclotron resonant scattering of relativistic electrons by EMIC waves. Quantitative analysis demonstrates that even with the existence of He+ band EMIC waves, it is the H+ band EMIC w. . .
Date: 05/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025726 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025726
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2018
Authors: Qin Murong, Hudson Mary, Millan Mary, Woodger Leslie, and Shekhar Sapna
Title: Statistical investigation of the efficiency of EMIC waves in precipitating relativistic electrons
Abstract: Electromagnetic ion cyclotron (EMIC) waves have been proposed to cause Relativistic Electron Precipitation (REP). In our study, we carry out 4 years of analysis from 2013 to 2016, with relativistic electron precipitation spikes obtained from POES satellites and EMIC waves observation from Van Allen Probes. Among the 473 coincidence events when POES satellites go through the region conjugate to EMIC wave activity, only 127 are associated with REP. Additionally, the coincidence occurrence rate is about 10% higher than the random coincidence occurrence rate, indicating that EMIC waves and relativistic electrons can be statistically related, but the link is weaker than expected. H+ band EMIC waves have been regarded as less important than He+ band EMIC waves for the precipitation of relativist. . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025419 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025419
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