Ground and space signatures of VLF noise suppression by whistlers

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378289%3A_____%2F20%3A00522721" target="_blank" >RIV/68378289:_____/20:00522721 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216208:11320/20:10423174

Výsledek na webu

<a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JA027430" target="_blank" >https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JA027430</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1029/2019JA027430" target="_blank" >10.1029/2019JA027430</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Ground and space signatures of VLF noise suppression by whistlers

Popis výsledku v původním jazyce

VLF (VeryLow Frequency) spectrograms registered at Kannuslehto ground station, after cleaning them from strong sferics, reveal VLF noise suppression by whistlers and whistler echo trains, which consists in significant reduction in the noise spectral power after a strong whistler event. We have found similar effect in the VLF data from Van Allen Probe B taken in the equatorial region on L-shell similar to 3. Detailed analysis of the data shows that the whistler echo train and the VLF noise have small wave normal angles. Based on this observation, we limit our analysis to parallel (ducted) whistler wave propagation. The persistence of whistler echo train, as well as the VLF noise, suggests that in the events under discussion, plasma is unstable in the frequency range corresponding to the observed VLF noise band. In an attempt to explain the effect of VLF noise suppression, we follow up the long-standing idea that relates this effect to the reduction of free energy in the unstable plasma distribution by whistler echo train. To develop this idea into qualitative model, we have studied the motion of energetic electrons, responsible for the noise generation, in the field of ducted whistler echo train. We show that energetic electrons that make the main contribution to the growth rate of VLF noise, during their bounce oscillations in the magnetosphere, are subject to multiple resonant impacts from the whistler echo train. These lead to energetic electron diffusion in the phase space and the corresponding reduction in free energy of the unstable distribution.

Název v anglickém jazyce

Ground and space signatures of VLF noise suppression by whistlers

Popis výsledku anglicky

VLF (VeryLow Frequency) spectrograms registered at Kannuslehto ground station, after cleaning them from strong sferics, reveal VLF noise suppression by whistlers and whistler echo trains, which consists in significant reduction in the noise spectral power after a strong whistler event. We have found similar effect in the VLF data from Van Allen Probe B taken in the equatorial region on L-shell similar to 3. Detailed analysis of the data shows that the whistler echo train and the VLF noise have small wave normal angles. Based on this observation, we limit our analysis to parallel (ducted) whistler wave propagation. The persistence of whistler echo train, as well as the VLF noise, suggests that in the events under discussion, plasma is unstable in the frequency range corresponding to the observed VLF noise band. In an attempt to explain the effect of VLF noise suppression, we follow up the long-standing idea that relates this effect to the reduction of free energy in the unstable plasma distribution by whistler echo train. To develop this idea into qualitative model, we have studied the motion of energetic electrons, responsible for the noise generation, in the field of ducted whistler echo train. We show that energetic electrons that make the main contribution to the growth rate of VLF noise, during their bounce oscillations in the magnetosphere, are subject to multiple resonant impacts from the whistler echo train. These lead to energetic electron diffusion in the phase space and the corresponding reduction in free energy of the unstable distribution.

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

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2020

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

125

Číslo periodika v rámci svazku

2

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

14

Strana od-do

e2019JA027430

Kód UT WoS článku

000535395800051

EID výsledku v databázi Scopus

2-s2.0-85092678905