Large amplitude undulations of evening site diffuse aurorae. Optical characteristics and conditions of generation

Autor: V. C. Roldugin, V. G. Vorobjev, O. I. Yagodkina
Rok vydání: 2015
Předmět:
Zdroj: Geomagnetism and Aeronomy. 55:41-50
ISSN: 1555-645X
0016-7932
DOI: 10.1134/s0016793215010132
Popis: Optical characteristics of large amplitude undulations (LAU) of diffuse aurorae observed by all-sky cameras at Kola Peninsula on December 28, 2010 were examined. Both interplanetary medium conditions and characteristics of magnetic activity before and during LAU were analyzed. It was shown that the development of undulations could be activated by sharp short-living of ∼20 minutes solar wind dynamic pressure impulse and existence of the undulations during about two hours was supported by electric field of stationary magnetospheric convection originated from large smoothly changed southward IMF Bz component of about −12nT. The altitude of undulation luminosity determined by triangulation method was 120 ± 10 km. The undulations amplitude changed from about 100 to 300 km and the average wavelength was ∼250 km. The undulations were observed moving westward with the average phase velocity of ∼0.7 km/s. The pass of DMSP F16 spacecraft just along “the tongue” of undulations showed that the wave of luminosity was located in the region of the predominantly ion (proton) precipitation with the average energy of particles of ∼18 keV. Rayed auroral structures were observed continuously in the region of diffuse aurorae during time interval of LAU existence. These structures were observed moving westward with the velocity of about 2 km/s that corresponds to the northward electric field of ∼100 mV/m.
Databáze: OpenAIRE
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