Localization of the Source of Quasiperiodic VLF Emissions in the Magnetosphere by Using Simultaneous Ground and Space Observations: A Case Study

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378289%3A_____%2F20%3A00538380" target="_blank" >RIV/68378289:_____/20:00538380 - isvavai.cz</a>

Alternative codes found

RIV/00216208:11320/20:10423192

Result on the web

<a href="http://jultika.oulu.fi/files/nbnfi-fe2020052939702.pdf" target="_blank" >http://jultika.oulu.fi/files/nbnfi-fe2020052939702.pdf</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1029/2020JA027776" target="_blank" >10.1029/2020JA027776</a>

Result language

angličtina

Original language name

Localization of the Source of Quasiperiodic VLF Emissions in the Magnetosphere by Using Simultaneous Ground and Space Observations: A Case Study

Original language description

We study quasiperiodic very low frequency (VLF) emissions observed simultaneously by Van Allen Probes spacecraft and Kannuslehto and Lovozero ground-based stations on 25 December 2015. Both Van Allen Probes A and B detected quasiperiodic emissions, probably originated from a common source, and observed on the ground. In order to locate possible regions of wave generation, we analyze wave-normal angles with respect to the geomagnetic field, Poynting flux direction, and cyclotron instability growth rate calculated by using the measured phase space density of energetic electrons. We demonstrate that even parallel wave propagation and proper (downward) Poynting flux direction are not sufficient for claiming observations to be in the source region. Agreement between the growth rate and emission bands was obtained for a restricted part of Van Allen Probe A trajectory corresponding to localized enhancement of plasma density with scale of 700 km. We employ spacecraft density data to build a model plasma profile and to calculate ray trajectories from the point of wave detection in space to the ionosphere and examine the possibility of their propagation toward the ground. For the considered event, the wave could propagate toward the ground in the geomagnetic flux tube with enhanced plasma density, which ensured ducted propagation. The region of wave exit was confirmed by the analysis of wave propagation direction at the ground detection point.nKey PointsnComplex analysis of generation region of quasiperiodic VLF emissions were observed simultaneously by two Van Allen Probes and on the ground Wave growth rate frequency band matched the observed emission band only in a localized (similar to 0.3 Earth radii) region along Van Allen Probe A trajectory Ray tracing demonstrated the importance of a density duct for wave propagation toward the ground

Czech name

—

Czech description

—

Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10305 - Fluids and plasma physics (including surface physics)

Project

<a href="/en/project/LTAUSA17070" target="_blank" >LTAUSA17070: Electromagnetic waves in planetary ionospheres and magnetospheres</a><br>

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2020

Confidentiality

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

Name of the periodical

Journal of Geophysical Research: Space Physics

ISSN

2169-9380

e-ISSN

—

Volume of the periodical

125

Issue of the periodical within the volume

5

Country of publishing house

US - UNITED STATES

Number of pages

14

Pages from-to

e2020JA027776

UT code for WoS article

000540229100041

EID of the result in the Scopus database

2-s2.0-85085369827