Statistical Study of ULF Waves in the Upstream Region: THEMIS Observations

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F21%3A10440088" target="_blank" >RIV/00216208:11320/21:10440088 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.mff.cuni.cz/veda/konference/wds/proc/pdf21/WDS21_05_f2_Salohub.pdf" target="_blank" >https://www.mff.cuni.cz/veda/konference/wds/proc/pdf21/WDS21_05_f2_Salohub.pdf</a>

DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Statistical Study of ULF Waves in the Upstream Region: THEMIS Observations

Popis výsledku v původním jazyce

The ion foreshock region is permanently filled by ultra-low frequency (ULF) waves and its spatial extent depends on the interplanetary magnetic field (IMF) orientation. When the IMF is nearly parallel to the Earth-Sun line, the foreshock occupies a large volume in front of the bow shock. The waves are generated through interactions between the back-streaming particles reflected from the bow shock and the incoming solar wind. It is supposed that the waves propagate sunward but they are convected by the solar wind flow back toward the bow shock and their amplitudes grow. However, our study shows that waves could be growing as well as decaying towards the bow shock under the quasi radial IMF. Nevertheless, a large statistics based on nine years of two point foreshock observations reveals their positive growth rate in a statistical sense. We demonstrate that the growth rate is larger for compressive variations of the magnetic field strength and density than for components of the magnetic field. We have found that the growth rate depends on the location of observing spacecraft with respect to the Moon; if the spacecraft is close to the lunar surface, the growth rate is close to zero or even negative. We discuss the role and importance of different spacecraft-Moon geometries and a possible mechanisms that can lead to the observed results.

Název v anglickém jazyce

Statistical Study of ULF Waves in the Upstream Region: THEMIS Observations

Popis výsledku anglicky

The ion foreshock region is permanently filled by ultra-low frequency (ULF) waves and its spatial extent depends on the interplanetary magnetic field (IMF) orientation. When the IMF is nearly parallel to the Earth-Sun line, the foreshock occupies a large volume in front of the bow shock. The waves are generated through interactions between the back-streaming particles reflected from the bow shock and the incoming solar wind. It is supposed that the waves propagate sunward but they are convected by the solar wind flow back toward the bow shock and their amplitudes grow. However, our study shows that waves could be growing as well as decaying towards the bow shock under the quasi radial IMF. Nevertheless, a large statistics based on nine years of two point foreshock observations reveals their positive growth rate in a statistical sense. We demonstrate that the growth rate is larger for compressive variations of the magnetic field strength and density than for components of the magnetic field. We have found that the growth rate depends on the location of observing spacecraft with respect to the Moon; if the spacecraft is close to the lunar surface, the growth rate is close to zero or even negative. We discuss the role and importance of different spacecraft-Moon geometries and a possible mechanisms that can lead to the observed results.

Druh

D - Stať ve sborníku

CEP obor

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OECD FORD obor

10305 - Fluids and plasma physics (including surface physics)

Projekt

<a href="/cs/project/GA21-26463S" target="_blank" >GA21-26463S: Procesy na magnetopauze, jejich příčiny a následky</a><br>

Návaznosti

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

Rok uplatnění

2021

Kód důvěrnosti údajů

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

Název statě ve sborníku

WDS&apos;21 Proceedings of Contributed Papers — Physics

ISBN

978-80-7378-455-3

ISSN

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e-ISSN

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Počet stran výsledku

7

Strana od-do

34-40

Název nakladatele

Matfyzpress

Místo vydání

Praha

Místo konání akce

Praha/ZOOM

Datum konání akce

15. 6. 2021

Typ akce podle státní příslušnosti

EUR - Evropská akce

Kód UT WoS článku

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