Very low frequency radio events with a reduced intensity observed by the low-altitude DEMETER spacecraft

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378289%3A_____%2F15%3A00449132" target="_blank" >RIV/68378289:_____/15:00449132 - isvavai.cz</a>
Alternative codes found
RIV/00216208:11320/15:10319780
Result on the web
<a href="http://dx.doi.org/10.1002/2015JA021607" target="_blank" >http://dx.doi.org/10.1002/2015JA021607</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1002/2015JA021607" target="_blank" >10.1002/2015JA021607</a>

Result language
angličtina
Original language name
Very low frequency radio events with a reduced intensity observed by the low-altitude DEMETER spacecraft
Original language description
We present results of a systematic study of unusual very low frequency (VLF) radio events with a reduced intensity observed in the frequency-time spectrograms measured by the low-orbiting DEMETER spacecraft. They occur exclusively on the nightside. During these events, the intensity of fractional hop whistlers at specific frequencies is significantly reduced. These frequencies are usually above about 3.4 kHz (second Earth-ionosphere waveguide cut-off frequency), but about 20% of events extend down to about 1.7 kHz (first Earth-ionosphere waveguide cut-off frequency). The frequencies of a reduced intensity vary smoothly with time. We have inspected 6.5 years of DEMETER data and we identified in total 1601 such events. We present a simple model of the event formation based on the wave propagation in the Earth-ionosphere waveguide. We apply the model to two selected events, and we demonstrate that the model is able to reproduce both the minimum frequencies of the events and their approximate frequency-time shapes. The overall geographic distribution of the events is shifted by about 3000 km westward and slightly southward with respect to the areas with high long-term average lightning activity.
Czech name
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Czech description
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Type
J<sub>x</sub> - Unclassified - Peer-reviewed scientific article (Jimp, Jsc and Jost)
CEP classification
BL - Plasma physics and discharge through gases
OECD FORD branch
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Project
Result was created during the realization of more than one project. More information in the Projects tab.
Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year
2015
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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