VLF electromagnetic emissions in the inner magnetosphere: Longitudinal dependence

0477970 - ÚFA 2018 BE eng A - Abstrakt
Záhlava, J. - Němec, F. - Santolík, Ondřej - Kolmašová, Ivana - Hospodarsky, G. B. - Parrot, M. - Kurth, W. S. - Kletzing, C. - Cornilleau-Wehrlin, N.
VLF electromagnetic emissions in the inner magnetosphere: Longitudinal dependence.
Papers from URSI: XXXIInd General Assembly and Scientific Symposium (URSI GASS). Ghent: URSI, 2017. H41P-1.
[URSI General Assembly and Scientific Symposium (URSI GASS) 2017 /32./. 19.08.2017-26.08.2017, Montreal]
Institucionální podpora: RVO:68378289
Klíčová slova: inner magnetosphere * very low frequency (VLF) electromagnetic waves * DEMETER spacecraft * Van Allen Probes * plasmapause density models * plasma density measurements
Kód oboru RIV: BL - Fyzika plazmatu a výboje v plynech

The intensity of very low frequency (VLF) electromagnetic waves in the Earth's inner magnetosphere is usually statistically described as a function of their frequency, L-shell, magnetic local time (MLT), and geomagnetic activity. In the present study, we investigate a possible dependence of the intensity of these electromagnetic waves on the geomagnetic longitude, i.e., a parameter typically unconsidered in former studies. We compare the results obtained by the low altitude (~700 km) DEMETER spacecraft (2004-2010), by the Van Allen Probes (2012-2016, still operating), and by the Cluster spacecraft (2001-2016, still operating). Empirical plasmapause density models and local plasma density measurements are used to distinguish the measurements performed inside/outside the plasmasphere. Moreover, multicomponent wave measurements performed by the Van Allen Probes and Cluster spacecraft allow us to perform a detailed wave analysis, and to separate the contributing wave phenomena according to their directions of propagation/polarization properties. We demonstrate that while there is principally no longitudinal dependence of the wave intensity during the daytime, the wave intensity measured during the nighttime exhibits a significant longitudinal variation, peaking at geomagnetic longitudes corresponding to individual continents. This effect seems to be most pronounced within the plasmasphere. The obtained results suggest that the waves of a terrestrial origin, especially those from the lightning activity, may significantly affect the overall wave intensity in the magnetosphere. They also suggest that a non-negligible part of the wave activity in the plasmaspheric hiss frequency band likely originates from lightning.
Trvalý link: http://hdl.handle.net/11104/0274209