Doppler Shifted Alpha Transmitter Signals in the Conjugate Hemisphere: DEMETER Spacecraft Observations and Raytracing Modeling

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378289%3A_____%2F21%3A00542945" target="_blank" >RIV/68378289:_____/21:00542945 - isvavai.cz</a>

Alternative codes found

RIV/00216208:11320/21:10439696

Result on the web

<a href="https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JA029017" target="_blank" >https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JA029017</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1029/2020JA029017" target="_blank" >10.1029/2020JA029017</a>

Result language

angličtina

Original language name

Doppler Shifted Alpha Transmitter Signals in the Conjugate Hemisphere: DEMETER Spacecraft Observations and Raytracing Modeling

Original language description

Alpha navigation transmitters are very low frequency (VLF) transmitters operating at mid-latitudes, which use a specific discrete radiation pattern at three distinct frequencies (11.9, 12.6, and 14.9 kHz). The transmitters are located in the northern hemisphere, but the radiated signals propagate through the magnetosphere to the conjugate hemisphere, where they are detectable by low-altitude spacecraft. We present an analysis of such signals detected by the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions spacecraft at an altitude of about 660 km. It is found that, due to a Doppler shift, the observed signal frequencies can be at times rather different than the radiated frequencies. This indicates wave propagation at large wave normal angles (close to the resonance cone). Simultaneous observations of the same signal with different Doppler shifts reveal three distinct ways of signal propagation: (i) ducted propagation, (ii) unducted propagation, and (iii) propagation interpreted as only partially ducted. A raytracing analysis is employed to obtain typical wave trajectories corresponding to the individual ways of signal propagation and respective Doppler shifts. A reasonable agreement between the observed and calculated Doppler shifts is obtained. Our results demonstrate the peculiarities of VLF signal propagation throughout the magnetosphere and the possibility of using Doppler shifts to estimate wave normal angles.

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/GA21-01813S" target="_blank" >GA21-01813S: Anthropogenic electromagnetic emissions and their effects on the Earth’s inner magnetosphere</a><br>

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2021

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

2169-9402

Volume of the periodical

126

Issue of the periodical within the volume

4

Country of publishing house

US - UNITED STATES

Number of pages

14

Pages from-to

e2020JA029017

UT code for WoS article

000645003000021

EID of the result in the Scopus database

2-s2.0-85104953495