Poynting vector and wave vector directions of equatorial chorus

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378289%3A_____%2F16%3A00472232" target="_blank" >RIV/68378289:_____/16:00472232 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216208:11320/16:10336425

Výsledek na webu

<a href="http://dx.doi.org/10.1002/2016JA023389" target="_blank" >http://dx.doi.org/10.1002/2016JA023389</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1002/2016JA023389" target="_blank" >10.1002/2016JA023389</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Poynting vector and wave vector directions of equatorial chorus

Popis výsledku v původním jazyce

We present new results on wave vectors and Poynting vectors of chorus rising and falling tones on the basis of 6 years of THEMIS (Time History of Events and Macroscale Interactions during Substorms) observations. The majority of wave vectors is closely aligned with the direction of the ambient magnetic field (B-0). Oblique wave vectors are confined to the magnetic meridional plane, pointing away from Earth. Poynting vectors are found to be almost parallel to B-0. We show, for the first time, that slightly oblique Poynting vectors are directed away from Earth for rising tones and toward Earth for falling tones. For the majority of lower band chorus elements, the mutual orientation between Poynting vectors and wave vectors can be explained by whistler mode dispersion in a homogeneous collisionless cold plasma. Upper band chorus seems to require inclusion of collisional processes or taking into account azimuthal anisotropies in the propagation medium. The latitudinal extension of the equatorial source region can be limited to +/- 6 degrees around the B-0 minimum or approximately +/- 5000 km along magnetic field lines. We find increasing Poynting flux and focusing of Poynting vectors on the B-0 direction with increasing latitude. Also, wave vectors become most often more field aligned. A smaller group of chorus generated with very oblique wave normals tends to stay close to the whistler mode resonance cone. This suggests that close to the equatorial source region (within similar to 20 degrees latitude), a wave guidance mechanism is relevant, for example, in ducts of depleted or enhanced plasma density.

Název v anglickém jazyce

Poynting vector and wave vector directions of equatorial chorus

Popis výsledku anglicky

We present new results on wave vectors and Poynting vectors of chorus rising and falling tones on the basis of 6 years of THEMIS (Time History of Events and Macroscale Interactions during Substorms) observations. The majority of wave vectors is closely aligned with the direction of the ambient magnetic field (B-0). Oblique wave vectors are confined to the magnetic meridional plane, pointing away from Earth. Poynting vectors are found to be almost parallel to B-0. We show, for the first time, that slightly oblique Poynting vectors are directed away from Earth for rising tones and toward Earth for falling tones. For the majority of lower band chorus elements, the mutual orientation between Poynting vectors and wave vectors can be explained by whistler mode dispersion in a homogeneous collisionless cold plasma. Upper band chorus seems to require inclusion of collisional processes or taking into account azimuthal anisotropies in the propagation medium. The latitudinal extension of the equatorial source region can be limited to +/- 6 degrees around the B-0 minimum or approximately +/- 5000 km along magnetic field lines. We find increasing Poynting flux and focusing of Poynting vectors on the B-0 direction with increasing latitude. Also, wave vectors become most often more field aligned. A smaller group of chorus generated with very oblique wave normals tends to stay close to the whistler mode resonance cone. This suggests that close to the equatorial source region (within similar to 20 degrees latitude), a wave guidance mechanism is relevant, for example, in ducts of depleted or enhanced plasma density.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

BL - Fyzika plasmatu a výboje v plynech

OECD FORD obor

—

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2016

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

121

Číslo periodika v rámci svazku

12

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

17

Strana od-do

11912-11928

Kód UT WoS článku

000393183300020

EID výsledku v databázi Scopus

2-s2.0-85007085705