Fine Harmonic Structure of Equatorial Noise with a Quasiperiodic Modulation

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378289%3A_____%2F20%3A00538497" target="_blank" >RIV/68378289:_____/20:00538497 - isvavai.cz</a>

Alternative codes found

RIV/00216208:11320/20:10423168

Result on the web

<a href="https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JA027509" target="_blank" >https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JA027509</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1029/2019JA027509" target="_blank" >10.1029/2019JA027509</a>

Result language

angličtina

Original language name

Fine Harmonic Structure of Equatorial Noise with a Quasiperiodic Modulation

Original language description

Equatorial noise emissions (fast magnetosonic waves) are electromagnetic waves observed routinely in the equatorial region of the inner magnetosphere. They propagate with wave vectors nearly perpendicular to the ambient magnetic field: that is, they are limited to frequencies below the lower hybrid frequency. The waves are generated by instabilities of ring-like proton distribution functions, which result in their fine harmonic structure with intensity maxima close to harmonics of the proton cyclotron frequency in the source region. Although most equatorial noise emissions are continuous in time, some events exhibit a clear quasiperiodic time modulation of the wave intensity, with typical modulation periods on the order of minutes. We analyze 72 such events (17 observed by the Cluster spacecraft, 55 observed by the Van Allen Probes spacecraft) for which high-resolution data were available. The analysis of the observed harmonic structure allows us to determine source radial distances of the events. It is found that the calculated source radial distances are generally close to the radial distances where the events were observed. The harmonic numbers where the events are generated range between about 12 and 30. Two events for which the spacecraft passed through the generation region were identified and analyzed. No simultaneous ultra-low-frequency magnetic field pulsations and no periodic plasma number density variations were observed. Although the in situ measured proton distribution functions were shown to be responsible for the wave growth, an insufficient resolution of the particle instruments prevented us from detecting a quasiperiodic modulation possibly present in the particle data.

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

Result was created during the realization of more than one project. More information in the Projects tab.

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

3

Country of publishing house

US - UNITED STATES

Number of pages

12

Pages from-to

e2019JA027509

UT code for WoS article

000535389600063

EID of the result in the Scopus database

2-s2.0-85082337410