Browsing by Author "Xiong, Ying"
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Item On the Origin of Ionospheric Hiss: A Conjugate Observation(Amer Geophysical Union, 2018-11-05) Zhima, Zeren; Chen, Lunjin; Xiong, Ying; Cao, Jinbin; Fu, Huishan; Chen, LunjinWe present a conjugate observation on whistler mode electromagnetic hiss from the low Earth orbit satellite Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) and the high-altitude elliptical orbit spacecraft Time History of Events and Macroscale Interactions during Substorms (THEMIS). The conjugate observation was performed at 14:51:10 to 15:12:00 UT on 15 June 2010, when DEMETER was flying across the L shell region from ~1.39 to 2.80 at an altitude of ~660 km; meanwhile, THEMIS probes were passing through the L shell region from ~1.64 to 1.91 at altitudes from ~1.6 to 2.0 R_E. The conjugated observations demonstrate similar time-frequency structures between the ionospheric hiss (~350 to 800 Hz) captured by DEMETER and the plasmaspheric hiss (~350 to 900 Hz) recorded by THEMIS probes, including similar peak frequencies (~500 to 600 Hz), similar lower cutoff frequencies (~350 to 400 Hz), and upper cutoff frequencies (~730 to 800 Hz). The wave vector analyses show that the ionospheric hiss propagates obliquely downward to the Earth and slightly equatorward with right-handed polarization, suggesting that its source comes from higher altitudes. Ray tracing simulations with the constraint of observations verify that the connection between ionospheric and plasmaspheric hiss is physically possible through wave propagation. This study provides direct observational evidence to support the mechanism that high-altitude plasmaspheric hiss is responsible for the generation of low-altitude ionospheric hiss.Item Relativistic Electron's Butterfly Pitch Angle Distribution Modulated by Localized Background Magnetic Field Perturbation Driven by Hot Ring Current Ions(Amer Geophysical Union, 2017-05-21) Xiong, Ying; Chen, Lunjin; Xie, Lun; Fu, Suiyan; Xia, Zhiyang; Pu, Zuyin; 0000-0003-2489-3571 (Chen, L); Chen, Lunjin; Xia, ZhiyangDayside modulated relativistic electron's butterfly pitch angle distributions (PADs) from ~ 200 keV to 2.6 MeV were observed by Van Allen Probe B at L = 5.3 on 15 November 2013. They were associated with localized magnetic dip driven by hot ring current ion (60-100 keV proton and 60-200 keV helium and oxygen) injections. We reproduce the electron's butterfly PADs at satellite's location using test particle simulation. The simulation results illustrate that a negative radial flux gradient contributes primarily to the formation of the modulated electron's butterfly PADs through inward transport due to the inductive electric field, while deceleration due to the inductive electric field and pitch angle change also makes in part contribution. We suggest that localized magnetic field perturbation, which is a frequent phenomenon in the magnetosphere during magnetic disturbances, is of great importance for creating electron's butterfly PADs in the Earth's radiation belts.