Power line harmonic radiation observed by satellite: Properties and propagation through the ionosphere

Němec, F.; Santolı́k, O.; Parrot, M.; Bortnik, J.

doi:10.1029/2008ja013184

Cited by 41 publications

(61 citation statements)

References 31 publications

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“…The influenced locations follow the industrialized areas well (Němec et al, , ), and thus they exhibit a clear longitudinal dependence. However, the radiated signals are typically rather weak and narrowband (Němec et al, ), and their overall effect on the wave intensity in the inner magnetosphere is thus likely rather negligible (Němec, Parrot, & Santolík, ). Third, the observed longitudinal dependence might be due to the asymmetric geomagnetic field.…”

Section: Discussionmentioning

confidence: 99%

Longitudinal Dependence of Whistler Mode Electromagnetic Waves in the Earth's Inner Magnetosphere

et al. 2018

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We use the measurements performed by the DEMETER (2004–010) and the Van Allen Probes (2012–016, still operating) spacecraft to investigate the longitudinal dependence of the intensity of whistler mode waves in the Earth's inner magnetosphere. We show that a significant longitudinal dependence is observed inside the plasmasphere on the nightside, primarily in the frequency range 400 Hz to 2 kHz. On the other hand, almost no longitudinal dependence is observed on the dayside. The obtained results are compared to the lightning occurrence rate provided by the Optical Transient Detector/Lightning Imaging Sensor mission normalized by a factor accounting for the ionospheric attenuation. The agreement between the two dependencies indicates that lightning‐generated electromagnetic waves may be responsible for of the observed effect, thus substantially affecting the overall wave intensity in the given frequency range. Finally, we show that the longitudinal dependence is most pronounced for waves with oblique wave of normal angles.

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Section: Discussionmentioning

confidence: 99%

Longitudinal Dependence of Whistler Mode Electromagnetic Waves in the Earth's Inner Magnetosphere

et al. 2018

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“… Němec et al [2007a] performed a detailed comparison of the two classes of events using the data from the DEMETER satellite. The second class of events was shown to be directly related to electromagnetic radiation from electric power systems on the ground [ Němec et al , 2006, 2007b, 2008].…”

Section: Introductionmentioning

confidence: 99%

Detailed properties of magnetospheric line radiation events observed by the DEMETER spacecraft

Němec¹,

Parrot²,

Santolı́k³

2012

J. Geophys. Res.

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[1] Magnetospheric line radiation (MLR) events are electromagnetic waves in the frequency range of about 1-8 kHz observed in the inner magnetosphere that, when presented in a form of frequency-time spectrograms, consist of several nearly parallel and almost equidistant intense lines. Although many observations of these events have been reported using ground-based instruments and a survey of a large data set based on low-altitude satellite data has been published recently, their origin remains unclear. We use low-altitude satellite observations of MLR events to study their detailed properties, namely, the frequency spacing of individual lines and their frequency drift. Since the satellite, unlike ground observatories, is moving, it allows us to analyze the properties of the events as a function of the position, especially L-shell. We show that neither the frequency spacing of the events nor their frequency drift varies significantly with the L-shell where the event is observed. Moreover, the frequency drift is generally positive. The individual lines forming the events cannot be explained as harmonics of the base frequency equal to the frequency spacing. We suggest that a possible generation mechanism might be an interaction between a wave of a carrier frequency and an additional wave with the frequency equal to the observed frequency spacing. We cannot exclude that it comes from human activity (power lines), but a magnetospheric origin is more likely. We suggest that the emissions might be guided by the plasmasphere inner boundary before they deviate to lower L-shells at altitudes of a few thousands of kilometers.Citation: Němec, F., M. Parrot, and O. Santolík (2012), Detailed properties of magnetospheric line radiation events observed by the DEMETER spacecraft,

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“…A careful analysis of satellite observations of such events with a line structure [ Němec et al , 2007a] showed it was possible to distinguish clearly a class of events called Power Line Harmonic Radiation (PLHR). These events are believed to be generated by electric power systems on the ground and are quite well understood [ Němec et al , 2006, 2007b, 2008]. They can be distinguished from MLR events by their frequency spacings corresponding exactly to 50 or 60 Hz and by very small line bandwidth (less than 3 Hz in the majority of cases, as reported by Němec et al [2008]).…”

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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Power line harmonic radiation observed by satellite: Properties and propagation through the ionosphere

Cited by 41 publications

References 31 publications

Longitudinal Dependence of Whistler Mode Electromagnetic Waves in the Earth's Inner Magnetosphere

Longitudinal Dependence of Whistler Mode Electromagnetic Waves in the Earth's Inner Magnetosphere

Detailed properties of magnetospheric line radiation events observed by the DEMETER spacecraft

Survey of magnetospheric line radiation events observed by the DEMETER spacecraft

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