Mode trapping in the plasmasphere

Turkakin, H.; Marchand, R.; Kale, Z. C.

doi:10.1029/2008ja013045

Cited by 9 publications

(6 citation statements)

References 28 publications

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“…G. Zong et al, 2009), and in the plasmasphere (e.g., X. Shi et al, 2017;Shinbori et al, 2004;Takahashi et al, 2010Takahashi et al, , 2018Takahashi et al, , 2009Turkakin et al, 2008). Knott et al (1985) reported that the dayside magnetospheric electric field shows transient signatures at the onset of SC, and these signatures are followed by oscillations with a period of ∼200 s Fujita et al (2003) used the 3-D MHD simulation to analyze the magnetospheric response to a magnetic impulse and showed that the initial electric field impulse is dominantly dusk-to-dawn direction in the dayside magnetosphere due to the passage of fast compressional mode wave.…”

Section: Resultsmentioning

confidence: 99%

“…Previous observations have demonstrated that the passage of the compressional mode waves can induce the distinct ULF waves in the magnetosphere (e.g., Hudson et al., 2004; Sarris et al., 2010; Q. Shi et al., 2013; Wilken et al., 1982; Q. G. Zong et al., 2009), and in the plasmasphere (e.g., X. Shi et al., 2017; Shinbori et al., 2004; Takahashi et al., 2010, 2018, 2009; Turkakin et al., 2008). Knott et al.…”

Section: Resultsmentioning

confidence: 99%

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ULF Fluctuation of Low‐Latitude Ionospheric Electric Fields During Sudden Commencements

et al. 2022

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We use the C/NOFS satellite observations to provide the direct evidence for ultra‐low‐frequency (ULF) fluctuations in the low‐latitude ionospheric electric field during the sudden commencement (SC) on 8 March 2012. The meridional plasma drift shows a sudden downward motion with a large amplitude after SC onset. This initial westward electric field signature is followed by ULF fluctuations with periods of 28–100 s. Further, C/NOFS observations show that the ionospheric zonal electric field and compressional component of geomagnetic field present the similar ULF fluctuations with a ∼90° phase difference, indicating the existence of a standing compressional mode wave. The fluctuations in the ionospheric electric field and horizontal component of the geomagnetic field on the ground also exhibit a high correlation and the frequency of the ground‐based geomagnetic field shows no dependence with latitudes. These results suggest that the ULF waves in the ionospheric electric field may be associated with a cavity mode. We also show the ULF waves in ionospheric electric fields in other cases. The ULF wave electric fields provide important information on the ionospheric studies and ionosphere‐magnetosphere coupling in low latitudes.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

ULF Fluctuation of Low‐Latitude Ionospheric Electric Fields During Sudden Commencements

et al. 2022

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“…6, 7), which was much smaller than the transverse wave scale of~0.8 R E for the PSW with m-value at a geocentric distance of 4.5 R E , satisfying the requirement of the interface width in exciting surface waves 47 . The sharp discontinuity in the density led the magnetosonic wave to be undamped 24,46,48 , allowing excitation of a standing surface eigenmode, i.e., the PSW propagating sunward/westward at the plasmapause boundary and along the field lines to both the northern and southern polar ionosphere. Using the plasmapause crossing measurements, it is estimated that the frequency of the fundamental poloidal wave is 1.35-2.11 mHz, close to 1.5 mHz (see the Methods section, estimation of eigenfrequency).…”

Section: Discussionmentioning

confidence: 99%

Plasmapause surface wave oscillates the magnetosphere and diffuse aurora

Guo

Dunn

et al. 2020

Nat Commun

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Energy circulation in geospace lies at the heart of space weather research. In the inner magnetosphere, the steep plasmapause boundary separates the cold dense plasmasphere, which corotates with the planet, from the hot ring current/plasma sheet outside. Theoretical studies suggested that plasmapause surface waves related to the sharp inhomogeneity exist and act as a source of geomagnetic pulsations, but direct evidence of the waves and their role in magnetospheric dynamics have not yet been detected. Here, we show direct observations of a plasmapause surface wave and its impacts during a geomagnetic storm using multisatellite and ground-based measurements. The wave oscillates the plasmapause in the afternoon-dusk sector, triggers sawtooth auroral displays, and drives outward-propagating ultra-low frequency waves. We also show that the surface-wave-driven sawtooth auroras occurred in more than 90% of geomagnetic storms during 2014-2018, indicating that they are a systematic and crucial process in driving space energy dissipation.

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“…It is widely accepted that fast mode waves which are generated by SSC/si would propagate through the magnetosphere [ Hudson et al ., ; Sarris et al ., ; Zhang et al ., ; Zong et al ., ]. Furthermore, multipoint observations provide new evidence that fast mode waves can be trapped in the plasmasphere [ Takahashi et al ., , ; Turkakin et al ., ]. Through comparison of magnetic field observations in the topside ionosphere and on the ground, nighttime Pi2 and Pc3 waves at low latitudes are considered to be generated by the direct transmission of fast mode waves toward the ground [ Cuturrufo et al ., ; Pilipenko et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Observations of ULF waves on the ground and ionospheric Doppler shifts during storm sudden commencement

et al. 2016

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Using data from ground‐based magnetometers and HF Doppler sounder, we study ultralow frequency (ULF) waves excited during the storm sudden commencement (SSC) on 8 March 2012 and find possible evidence on the link between ULF waves and ionospheric Doppler shifts. Pc1–Pc2 ULF waves are observed from 11:04 to 11:27 UT after the SSC by ground stations of L shell ranging from 1.06 to 2.31, mapping to the topside ionosphere. There are weak responses in this frequency range in the power spectra of ionospheric Doppler shift. From 11:19 to 11:23 UT, oscillations of magnetic field in a lower frequency range of Pc3–Pc4 are observed and are well correlated with the trace of Doppler shift. It is thus suggested that ionospheric Doppler shift can response to ULF oscillations in magnetic field in various frequency ranges, especially in the frequency range of Pc3–Pc4 and below. This paper demonstrates a new mechanism of magnetosphere‐ionosphere coupling.

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Mode trapping in the plasmasphere

Cited by 9 publications

References 28 publications

ULF Fluctuation of Low‐Latitude Ionospheric Electric Fields During Sudden Commencements

ULF Fluctuation of Low‐Latitude Ionospheric Electric Fields During Sudden Commencements

Plasmapause surface wave oscillates the magnetosphere and diffuse aurora

Observations of ULF waves on the ground and ionospheric Doppler shifts during storm sudden commencement

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