Found 9 entries in the Bibliography.

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An Automatic Detection Algorithm Applied to Fast Magnetosonic Waves With Observations of the Van Allen Probes

Fast magnetosonic (MS) waves can play an important role in the evolution of the inner magnetosphere. However, there is still not an effective method to quantitatively identify such waves for observations of the Van Allen Probes reasonably. In this paper, we used Van Allen Probes data from 18 September 2012 to 30 September 2014 to find a more comprehensive automatic detection algorithm for fast MS waves through statistical analysis of the major properties, including the planarity, ellipticity, and wave normal angle of whole f ...

Yuan, Zhigang; Yao, Fei; Yu, Xiongdong; Huang, Shiyong; Ouyang, Zhihai;

YEAR: 2019     DOI: 10.1029/2018JA026387

ellipticity; magnetosonic wave; normalized distribution; planarity; Van Allen Probes; wave normal angle

Excitation of extremely low-frequency chorus emissions: The role of background plasma density

Low-frequency chorus emissions have recently attracted much attention due to the suggestion that they may play important roles in the dynamics of the Van Allen Belts. However, the mechanism (s) generating these low-frequency chorus emissions have not been well understood. . In this letter, we report an interesting case in which background plasma density lowered the lower cutoff frequency of chorus emissions from above 0.1 f ce (typical ordinary chorus) to 0.02 f ce (extremely low-frequency chorus). Those extremely low-freque ...

Yu, Xiongdong; Yuan, Zhigang; Huang, Shiyong; Yao, Fei; Qiao, Zheng; Wygant, John; Funsten, Herbert;

YEAR: 2019     DOI: 10.26464/epp2019001

anisotropic temperature instability; linear growth rate; low-frequency chorus emissions; Van Allen Probes; whistler mode

Simultaneous trapping of EMIC and MS waves by background plasmas

Electromagnetic ion cyclotron waves and fast magnetosonic waves are found to be simultaneously modulated by background plasma density: both kinds of waves were observed in high plasma density regions but vanished in low density regions. Theoretical analysis based on Snell\textquoterights law and linear growth theory have been utilized to investigate the physical mechanisms driving such modulation. It is suggested that the modulation of fast magnetosonic waves might be due to trapping by plasma density structures, which resul ...

Yuan, Zhigang; Yu, Xiongdong; Ouyang, Zhihai; Yao, Fei; Huang, Shiyong; Funsten, H.;

YEAR: 2019     DOI: 10.1029/2018JA026149

EMIC waves; MS waves; Ring current ions; Van Allen Probes; Wave trapping


Response of banded whistler-mode waves to the enhancement of solar wind dynamic pressure in the inner Earth\textquoterights magnetosphere

With observations of Van Allen Probe A, in this letter we display a typical event where banded whistler waves shifted up their frequencies with frequency bands broadening as a response to the enhancement of solar wind dynamic pressure. Meanwhile, the anisotropy of electrons with energies about several tens of keV was observed to increase. Through the comparison of the calculated wave growth rates and observed wave spectral intensity, we suggest that those banded whistler waves observed with frequencies shifted up and frequen ...

Yu, Xiongdong; Yuan, Zhigang; Li, Haimeng; Huang, Shiyong; Wang, Dedong; Yao, Fei; Funsten, H.; Wygant, J.;

YEAR: 2018     DOI: 10.1029/2018GL078849

Banded whistler-mode waves; Frequency properties; inner magnetosphere; solar wind dynamic pressure; Van Allen Probes

Precipitation of radiation belt electrons by EMIC waves with conjugated observations of NOAA and Van Allen satellites

In this letter, we present unique conjugated satellite observations of MeV relativistic electron precipitation caused by electromagnetic ion cyclotron (EMIC) waves. On the outer boundary of the plasmasphere, the Van Allen probe observed EMIC waves. At ionospheric altitudes, the NOAA 16 satellite at the footprint of Van Allen probe simultaneously detected obvious flux enhancements for precipitating >MeV radiation belt electrons, but not for precipitating

Yuan, Zhigang; Liu, Kun; Yu, Xiongdong; Yao, Fei; Huang, Shiyong; Wang, Dedong; Ouyang, Zhihai;

YEAR: 2018     DOI: 10.1029/2018GL080481

Chorus; EMIC waves; Particle precipitation; Radiation belt; ring current; Van Allen Probes; Wave-particle interaction

Global distribution of proton rings and associated magnetosonic wave instability in the inner magnetosphere

Using the Van Allen Probe A observations, we obtained the global distribution of proton rings and calculated the linear wave growth rate of fast magnetosonic (MS) waves in the region L ~ 3-6. Our statistical and calculated results demonstrate that MS waves can be locally excited on the dayside outside the plasmapause, as well as in the dusk sector inside the plasmapause. The frequency range of unstable MS waves is strongly modulated by the ratio of the proton ring velocity (Vr) to the local Alfv\ en speed (VA). High harmonic ...

Yuan, Zhigang; Ouyang, Zhihai; Yu, Xiongdong; Huang, Shiyong; Yao, Fei; Funsten, H.;

YEAR: 2018     DOI: 10.1029/2018GL079999

Fast Magnetosonic Waves; linear growth rates; locally excited; low harmonic magnetosonic waves; Proton rings; Van Allen Probes

Cold Ion Heating by Magnetosonic Waves in a Density Cavity of the Plasmasphere

Fast magnetosonic (MS) waves play an important role in the dynamics of the inner magnetosphere. Theoretical prediction and simulation have demonstrated that MS waves can heat cold ions. However, direct observational evidence of cold ion heating by MS waves has so far remained elusive. In this paper, we show a typical event of cold ion heating by magnetosonic waves in a density cavity of the plasmasphere with observations of the Van Allen Probe mission on 22 August 2013. During enhancements of the MS wave intensity in the den ...

Yuan, Zhigang; Yu, Xiongdong; Huang, Shiyong; Qiao, Zheng; Yao, Fei; Funsten, Herbert;

YEAR: 2018     DOI: 10.1002/2017JA024919

cold ion heating; Density cavities; local linear growth rates; magnetosonic waves; Ring current ions; Van Allen Probes; \textquoteleftring\textquoteright distributions

Excitation of O + Band EMIC Waves Through H + Ring Velocity Distributions: Van Allen Probe Observations

A typical case of electromagnetic ion cyclotron (EMIC) emissions with both He+ band and O+ band waves was observed by Van Allen Probe A on 14 July 2014. These emissions occurred in the morning sector on the equator inside the plasmasphere, in which region O+ band EMIC waves prefer to appear. Through property analysis of these emissions, it is found that the He+ band EMIC waves are linearly polarized and propagating quasi-parallelly along the background magnetic field, while the O+ band ones are of linear and left-hand polari ...

Yu, Xiongdong; Yuan, Zhigang; Huang, Shiyong; Yao, Fei; Wang, Dedong; Funsten, Herbert; Wygant, John;

YEAR: 2018     DOI: 10.1002/grl.v45.310.1002/2018GL077109

linear wave growth; O+ band EMIC waves; ring distributions; Van Allen Probes


EMIC waves covering wide L shells: MMS and Van Allen Probes observations

During 04:45:00\textendash08:15:00 UT on 13 September in 2015, a case of Electromagnetic ion cyclotron (EMIC) waves covering wide L shells (L = 3.6\textendash9.4), observed by the Magnotospheric Multiscale 1 (MMS1) are reported. During the same time interval, EMIC waves observed by Van Allen Probes A (VAP-A) only occurred just outside the plasmapause. As the Van Allen Probes moved outside into a more tenuous plasma region, no intense waves were observed. Combined observations of MMS1 and VAP-A suggest that in the terrestrial ...

Yu, Xiongdong; Yuan, Zhigang; Huang, Shiyong; Wang, Dedong; Li, Haimeng; Qiao, Zheng; Yao, Fei;

YEAR: 2017     DOI: 10.1002/2017JA023982

EMIC waves; MMS; solar wind dynamic pressure; Van Allen Probes