The occurrence and wave properties of EMIC waves observed by the Magnetospheric Multiscale (MMS) mission

Wang, X. Y.; Huang, Suming; Allen, R. C.; Fu, H. S.; Deng, Xiaohua; Zhou, Mi; Burch, J. L.; Torbert, R. B.

doi:10.1002/2017ja024237

Cited by 50 publications

(71 citation statements)

References 70 publications

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“…EMIC waves are expected to be preferentially left-hand polarized and propagating roughly along the background magnetic field based on the basic plasma theory and in situ observations. However, the linearly dominated polarization and oblique propagating waves have also been presented by several recent statistical studies (Kim et al, 2010;Park et al, 2013;Wang et al, 2017). Our findings in this study are well consistent with those recent results.…”

Section: Wave Propertiessupporting

confidence: 94%

Global Characteristics of Electromagnetic Ion Cyclotron Waves Deduced From Swarm Satellites

et al. 2018

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It is well known that electromagnetic ion cyclotron (EMIC) waves play an important role in controlling particle dynamics inside the Earth's magnetosphere, especially in the outer radiation belt. In order to understand the results of wave‐particle interactions due to EMIC waves, it is important to know how the waves are distributed and what features they have. In this paper, we present some statistical analyses on the spatial distribution of EMIC waves in the low Earth orbit by using Swarm satellites from December 2013 to June 2017 (~3.5 years) as a function of magnetic local time, magnetic latitude, and magnetic longitude. We also study the wave characteristics such as ellipticity, wave normal angle, peak frequency, and wave power using our automatic wave detection algorithm based on the method of Bortnik et al. (2007, https://doi.org/10.1029/2006JA011900). We also investigate the geomagnetic control of the EMIC waves by comparing with geomagnetic activity represented by Kp and Dst indices. We find that EMIC waves are detected with a peak occurrence rate at midlatitude including subauroral region, dawn sector (3–7 magnetic local time), and linear polarization dominated with an oblique propagating direction to the background magnetic field. In addition, our result shows that the waves have some relation with geomagnetic activity; that is, they occur preferably during the geomagnetic storm's late recovery phase at low Earth orbit.

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Section: Wave Propertiessupporting

confidence: 94%

Global Characteristics of Electromagnetic Ion Cyclotron Waves Deduced From Swarm Satellites

et al. 2018

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“…For example, the median AE index is higher for wave occurring at the dusk sector (Figures 3c and 3g) where the waves are more intense. This finding is consistent with previous studies (e.g., Jun et al, 2019;Min et al, 2012;Saikin et al, 2015Saikin et al, , 2016Usanova et al, 2012;Wang et al, 2015;Wang et al, 2017), suggesting that the substorm injection of fresh hot ions at the duskside is the energy source for this intense EMIC wave generation. On the other hand, the median EMIC wave intensity observed in the noon sector is relatively small and is associated with smaller β ∥,p , larger anisotropies and smaller AE values as well as larger electron densities.…”

Section: Geophysical Research Letterssupporting

confidence: 93%

The Relationship Between EMIC Wave Properties and Proton Distributions Based on Van Allen Probes Observations

Yue

Jun

Bortnik

et al. 2019

Geophysical Research Letters

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Plasma kinetic theory predicts that sufficiently anisotropic proton distribution will excite electromagnetic ion cyclotron (EMIC) waves, which in turn relax the proton distribution to a marginally stable state creating an upper bound on the relaxed proton anisotropy. Here, using EMIC wave observations and coincident plasma measurements made by Van Allen Probes in the inner magnetosphere, we show that the proton distributions are well constrained by this instability to a marginally stable state. Near the threshold, the probability of EMIC wave occurrence is highest, having left‐handed polarization and observed near the magnetic equator with relatively small wave normal angles, indicating that these waves are locally generated. In addition, EMIC waves are distributed in two magnetic local time regions with different intensity. Compared with helium band waves, hydrogen band waves behave similarly except that they are often observed in low‐density regions. These results reveal several important features regarding EMIC waves excitation and propagation.

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“…Linear polarization would thus only be an effect of wave propagation. Linear-mode EMIC waves have also been reported by missions other than the VAPs Anderson et al, 1992;Min et al, 2012;X. Y. Wang et al, 2017).…”

Section: Combined Observationsmentioning

confidence: 92%

Storm Time EMIC Waves Observed by Swarm and Van Allen Probe Satellites

Wang

Lühr

et al. 2019

JGR Space Physics

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The temporal and spatial evolution of electromagnetic ion cyclotron (EMIC) waves during the magnetic storm of 21–29 June 2015 was investigated using high‐resolution magnetic field observations from Swarm constellation in the ionosphere and Van Allen Probes in the magnetosphere. Magnetospheric EMIC waves had a maximum occurrence frequency in the afternoon sector and shifted equatorward during the expansion phase and poleward during the recovery phase. However, ionospheric waves in subauroral regions occurred more frequently in the nighttime than during the day and exhibited less obvious latitudinal movements. During the main phase, dayside EMIC waves occurred in both the ionosphere and magnetosphere in response to the dramatic increase in the solar wind dynamic pressure. Waves were absent in the magnetosphere and ionosphere around the minimum SYM‐H. During the early recovery phase, He+ band EMIC waves were observed in the ionosphere and magnetosphere. During the late recovery phase, H+ band EMIC waves emerged in response to enhanced earthward convection during substorms in the premidnight sector. The occurrence of EMIC waves in the noon sector was affected by the intensity of substorm activity. Both ionospheric wave frequency and power were higher in the summer hemisphere than in the winter hemisphere. Waves were confined to an MLT interval of less than 5 hr with a duration of less than 186 min from coordinated observations. The results could provide additional insights into the spatial characteristics and propagation features of EMIC waves during storm periods.

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The occurrence and wave properties of EMIC waves observed by the Magnetospheric Multiscale (MMS) mission

Cited by 50 publications

References 70 publications

Global Characteristics of Electromagnetic Ion Cyclotron Waves Deduced From Swarm Satellites

Global Characteristics of Electromagnetic Ion Cyclotron Waves Deduced From Swarm Satellites

The Relationship Between EMIC Wave Properties and Proton Distributions Based on Van Allen Probes Observations

Storm Time EMIC Waves Observed by Swarm and Van Allen Probe Satellites

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