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

Kód výsledku v 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>

Nalezeny alternativní kódy

RIV/00216208:11320/15:10319780

Výsledek na webu

<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>

Jazyk výsledku

angličtina

Název v původním jazyce

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

Popis výsledku v původním jazyce

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.

Název v anglickém jazyce

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

Popis výsledku anglicky

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.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

BL - Fyzika plasmatu a výboje v plynech

OECD FORD obor

—

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2015

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Geophysical Research: Space Physics

ISSN

2169-9380

e-ISSN

—

Svazek periodika

120

Číslo periodika v rámci svazku

11

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

14

Strana od-do

9781-9794

Kód UT WoS článku

000368252100035

EID výsledku v databázi Scopus

2-s2.0-84955196843