ELF magnetospheric lines observed by DEMETER

Parrot, M.; Němec, F.; Santolı́k, O.; Berthelier, Jean‐Jacques

doi:10.5194/angeo-23-3301-2005

Cited by 18 publications

(14 citation statements)

References 32 publications

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“…Spectrogram results clearly indicate strong emissions before earthquakes. This is in agreement with the work done by Larkina et al (), Bhattacharya and Gwal () and Parrot et al (), who earlier detected electromagnetic emissions over earthquake regions. Zeng ZC et al () and Zhu T and Wang LW () studied average power spectrum density (APSD) of the electric field.…”

Section: Introductionsupporting

confidence: 93%

Examples of unusual ionospheric observations by the CSES prior to earthquakes

Yao¹,

Shen²,

Huang³

et al. 2018

Earth and Planetary Physics

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The CSES (China seismic electromagnetic satellite) was launched on February 2, 2018 in a circular polar orbit at an altitude of ~507 km. One of the main objectives of CSES is to search for and characterize ionospheric perturbations that can be associated with seismic activities, to better understand the generation mechanism of such perturbations. Its scientific payload can measure a broad frequency range of electromagnetic waves and some important plasma parameters. This paper is a first‐hand study of unusual observations recorded by the CSES over seismic regions prior to four earthquakes with M >7.0 since the satellite's launch. CSES detectors measured irregularities near the epicenter of these four earthquakes. It is already clear that data from instruments onboard the CSES will be of significant help in studies of characteristics of ionospheric perturbations related to earthquakes and their generation mechanisms.

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Section: Introductionsupporting

confidence: 93%

Examples of unusual ionospheric observations by the CSES prior to earthquakes

Yao¹,

Shen²,

Huang³

et al. 2018

Earth and Planetary Physics

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“…Their frequency‐time spectrograms are formed by several almost parallel and nearly horizontal intense lines. Although such events have been observed both on the ground (e.g., Helliwell et al, ; Rodger et al, , ) and in space (e.g., Bell et al, ; Němec et al, ; Parrot et al, ; Rodger et al, ), their origin is not yet clarified. Bullough () discussed a possible relation of MLR events to power line harmonic radiation.…”

Section: Introductionmentioning

confidence: 99%

Dependence of Properties of Magnetospheric Line Radiation and Quasiperiodic Emissions on Solar Wind Parameters and Geomagnetic Activity

et al. 2019

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Very low frequency electromagnetic waves in the inner magnetosphere sometimes exhibit either frequency or time modulation. These phenomena are called, respectively, magnetospheric line radiation (MLR) and quasiperiodic (QP) emissions. Data from Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions spacecraft were used to analyze their properties, such as MLR frequency spacing, QP modulation period, and QP intensity as functions of geomagnetic activity and solar wind parameters. Altogether, 1,152 MLR events and 2,172 QP emissions were analyzed. It is shown that the influence of the analyzed parameters on QP emissions is different for QP events with modulation periods shorter/longer than 20 s. While the properties of QP events with long modulation periods are significantly related to the geomagnetic activity and solar wind parameters, no such dependences are observed for events with short modulation periods. This suggests that there might be two types of QP emissions generated by two different mechanisms. It is further shown that there seems to be no relation between the properties of QP and MLR events observed at the same times. Finally, the event properties do not seem to be related to the whistler occurrence rate.

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“…Such emissions are usually called Magnetospheric Line Radiation (MLR). They have been reported both in ground observations [e.g., Rodger et al, 1999Rodger et al, , 2000Manninen, 2005] and low-altitude satellite data [e.g., Bell et al, 1982;Rodger et al, 1995;Parrot et al, 2005;Němec et al, 2007a]. However, their origin is still unknown.…”

Section: Introductionmentioning

confidence: 99%

Survey of magnetospheric line radiation events observed by the DEMETER spacecraft

et al. 2009

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[1] Magnetospheric line radiation (MLR) events are electromagnetic waves in the frequency range between about 1 and 8 kHz that, when presented as a frequency-time spectrogram, take the form of nearly parallel and clearly defined lines, which sometimes drift slightly in frequency. They have been observed both by satellites and ground-based instruments, but their origin is still unclear. We present a survey of these MLR waves observed by the DEMETER spacecraft (at an altitude of about 700 km). Three years of VLF Survey mode data were manually searched for MLR events, creating the largest event satellite database of about 650 events, which was then used to investigate the wave properties and geographical occurrence. Finally, the most favorable geomagnetic conditions (Kp and Dst indices) for the occurrence of MLR events have been found. It is shown that MLR events occur mostly at L > 2 (upper limit is given by a limitation of the spacecraft), they occur primarily inside the plasmasphere, and there is a lower number of events occurring over the Atlantic Ocean than elsewhere on the globe. The MLR events occur more often during the day and usually during, or after, periods of higher magnetic activity. Their frequencies usually lay between about 2 and 6 kHz, with the total frequency bandwidth of an observation being below 2 kHz in the majority of cases. Moreover, it is shown that the longitudinal dimensions of the MLR events can be as large as 100°and they can last for up to a few hours. Finally, we discuss a possibility that MLR events may be triggered by power line harmonic radiation (PLHR) and we report an event supporting this hypothesis.

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ELF magnetospheric lines observed by DEMETER

Cited by 18 publications

References 32 publications

Examples of unusual ionospheric observations by the CSES prior to earthquakes

Examples of unusual ionospheric observations by the CSES prior to earthquakes

Dependence of Properties of Magnetospheric Line Radiation and Quasiperiodic Emissions on Solar Wind Parameters and Geomagnetic Activity

Survey of magnetospheric line radiation events observed by the DEMETER spacecraft

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