Survey of magnetospheric line radiation events observed by the DEMETER spacecraft

Němec, F.; Parrot, M.; Santolı́k, O.; Rodger, Craig J.; Rycroft, M.J.; Hayosh, M.; Shklyar, D. R.; Демехов, А. Г.

doi:10.1029/2008ja014016

Cited by 18 publications

(53 citation statements)

References 16 publications

(33 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The database of the MLR events used was based on the data set from our previous study [ Němec et al , 2009] that we have extended till the end of September 2008 (i.e. we have added about 1 year of data).…”

Section: Discussionmentioning

confidence: 99%

“…we have added about 1 year of data). The events were visually identified in frequency‐time spectrograms of individual half‐orbits of DEMETER data and all the drawbacks discussed by Němec et al [2009] related to this procedure apply also to the presented paper. Namely, the identification of events is necessarily somewhat subjective and depends on the individual feeling of the observer.…”

Section: Discussionmentioning

confidence: 99%

“…However, the burst mode data have been used whenever available in order to improve the frequency resolution. We have used the list of MLR events compiled by Němec et al [2009] extended till the end of September 2008. MLR events were visually identified in the frequency‐time spectrograms corresponding to individual satellite half‐orbits.…”

Section: Data Setmentioning

confidence: 99%

“…They demonstrated that the event lasted for as long as 2 hours and spanned over a large area in the Northern Hemisphere (≈7,400,000 km 2 ). Results of a survey of MLR events observed by the DEMETER spacecraft were reported by Němec et al [2009]. They found that MLR events occur more often during the day than during the night and usually during, or after, periods of higher magnetic activity.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

Němec¹,

Parrot²,

Santolı́k³

2012

J. Geophys. Res.

Self Cite

View full text Add to dashboard Cite

[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,

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Data Setmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Němec¹,

Parrot²,

Santolı́k³

2012

J. Geophys. Res.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Banded VLF emissions are commonly observed in the inner magnetosphere and are typically interpreted as harmonics of either an artificial transmission frequency or a fundamental resonance such as the ion (or electron) gyrofrequency or plasma frequency. In addition to the well‐documented ion cyclotron harmonics [ Kintner , 1980; Koskinen et al , 1987; Chaston et al , 2002], these banded emissions include VLF chorus [ Burtis and Helliwell , 1969], VLF Hiss [ Titova et al , 2007], Power Line Harmonic Radiation [ Němec et al , 2006], and Magnetic Line Radiation [ Němec et al , 2009] among others. In the low altitude auroral region, waves at harmonics of the ion cyclotron frequency have been observed with FAST in association with both downgoing [ Cattell et al , 2002] and upgoing [ Chaston et al , 2002] ion beams.…”

Section: Introductionmentioning

confidence: 99%

Satellite observations of banded VLF emissions in conjunction with energy‐banded ions during very large geomagnetic storms

Colpitts¹,

Cattell²,

Kozyra³

et al. 2012

J. Geophys. Res.

View full text Add to dashboard Cite

Frequency‐banded electromagnetic VLF waves up to 2000 Hz are observed concurrently with warm (10 s to 10,000 s of eV) energy‐banded ions in the low latitude auroral and sub‐auroral zones during every large geomagnetic storm encountered by the FAST and DEMETER satellites. The banded ions and waves persist for several FAST or DEMETER orbits, lasting up to 12 h, in both dawn and dusk sectors, in both the northern and southern hemispheres. If the waves are generated at harmonics of the proton gyrofrequency, the inferred source region would be ∼4000 km altitude. Previous investigations have shown that such waves can propagate from this source region to the locations of both spacecraft. An investigation into the growth of waves at harmonics of fci in the inferred source region suggests that these emissions could be generated by ion bands similar to those observed at the same time as the waves. Magnetospheric waves such as these play a role in energy transfer between distinct particle populations and may contribute to ion heating and ion outflow as well as electron energization. All of these phenomena occur during the strongest magnetic storms. The appearance of the banded ions and associated wave activity suggests that there may be distinct changes in the geospace system that characterize large magnetic storms.

show abstract

Statistical investigation of VLF quasiperiodic emissions measured by the DEMETER spacecraft

et al. 2014

Self Cite

View full text Add to dashboard Cite

We present a survey of quasiperiodic (QP) ELF/VLF emissions detected onboard the DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) satellite (altitude of about 700 km, nearly Sun-synchronous orbit at 10:30/22:30 LT). Six years of data have been visually inspected for the presence of QP emissions with modulation periods higher than 10 s and with frequency bandwidths higher than 200 Hz. It is found that these QP events occur in about 5% of daytime half orbits, while they are basically absent during the night. The events occur predominantly during quiet geomagnetic conditions following the periods of enhanced geomagnetic activity. Their occurrence and properties are systematically analyzed. QP emissions occur most often at frequencies from about 750 Hz to 2 kHz, but they may be observed at frequencies as low as 500 Hz and as high as 8 kHz. Modulation periods of QP events may range from about 10 to 100 s, with typical values of 20 s. Frequency drifts of the identified events are generally positive, but they are lower for events with larger modulation periods. The events are usually limited to higher L values (L > 2). The upper L shell boundary of their occurrence could not be identified using the DEMETER data, but they are found to extend up to at least L~6. The occurrence rate of the events is significantly lower at the longitudes of the South Atlantic anomaly (by a factor of more than 2).

show abstract

Survey of magnetospheric line radiation events observed by the DEMETER spacecraft

Cited by 18 publications

References 16 publications

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

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

Satellite observations of banded VLF emissions in conjunction with energy‐banded ions during very large geomagnetic storms

Statistical investigation of VLF quasiperiodic emissions measured by the DEMETER spacecraft

Contact Info

Product

Resources

About