Selective Attenuation of Lightning-Generated Whistlers at Extralow Frequencies: DEMETER Spacecraft Observations

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F18%3A10389471" target="_blank" >RIV/00216208:11320/18:10389471 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/68378289:_____/18:00494082

Výsledek na webu

<a href="https://doi.org/10.1029/2018JA025879" target="_blank" >https://doi.org/10.1029/2018JA025879</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1029/2018JA025879" target="_blank" >10.1029/2018JA025879</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Selective Attenuation of Lightning-Generated Whistlers at Extralow Frequencies: DEMETER Spacecraft Observations

Popis výsledku v původním jazyce

Frequency-time spectrograms measured by the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) spacecraft (2004-2010, altitude about 700 km) at frequencies below 20 kHz sometimes contain lightning-generated whistlers whose intensity is significantly reduced at specific frequencies. The frequencies of the reduced intensity vary smoothly over the event duration, forming apparent curves in frequency-time spectrograms. Events at frequencies higher than the Earth-ionosphere waveguide cutoff frequency were explained by the interference of the first few waveguide modes of lightning-generated spherics propagating therein (Zahlava et al., 2015, https://doi.org/10.1002/2015JA021607. Here we present an analysis of events observed at frequencies lower than about 1 kHz. Altogether, we analyze 263 events identified at the times when DEMETER operated in the burst mode. The vast majority of the events (95%) took place during the nighttime, and they occurred more frequently during spring/autumn than during winter/summer. We present an overview of event properties. Moreover, measurements of all six electromagnetic field components performed by DEMETER allow us to perform a detailed wave analysis. It is shown that the emissions propagate with high wave normal angles inclined toward the Earth. We suggest that the events might be due to the wave propagation in the ionospheric waveguide formed around the refractive index maximum at the altitude of about 105 km.

Název v anglickém jazyce

Selective Attenuation of Lightning-Generated Whistlers at Extralow Frequencies: DEMETER Spacecraft Observations

Popis výsledku anglicky

Frequency-time spectrograms measured by the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) spacecraft (2004-2010, altitude about 700 km) at frequencies below 20 kHz sometimes contain lightning-generated whistlers whose intensity is significantly reduced at specific frequencies. The frequencies of the reduced intensity vary smoothly over the event duration, forming apparent curves in frequency-time spectrograms. Events at frequencies higher than the Earth-ionosphere waveguide cutoff frequency were explained by the interference of the first few waveguide modes of lightning-generated spherics propagating therein (Zahlava et al., 2015, https://doi.org/10.1002/2015JA021607. Here we present an analysis of events observed at frequencies lower than about 1 kHz. Altogether, we analyze 263 events identified at the times when DEMETER operated in the burst mode. The vast majority of the events (95%) took place during the nighttime, and they occurred more frequently during spring/autumn than during winter/summer. We present an overview of event properties. Moreover, measurements of all six electromagnetic field components performed by DEMETER allow us to perform a detailed wave analysis. It is shown that the emissions propagate with high wave normal angles inclined toward the Earth. We suggest that the events might be due to the wave propagation in the ionospheric waveguide formed around the refractive index maximum at the altitude of about 105 km.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10305 - Fluids and plasma physics (including surface physics)

Projekt

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

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2018

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

123

Číslo periodika v rámci svazku

10

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

10

Strana od-do

8631-8640

Kód UT WoS článku

000451038700035

EID výsledku v databázi Scopus

2-s2.0-85054602225