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Conjugate ground-spacecraft observations of VLF chorus elements
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SYSNO ASEP 0497713 Document Type A - Abstract R&D Document Type The record was not marked in the RIV R&D Document Type Není vybrán druh dokumentu Title Conjugate ground-spacecraft observations of VLF chorus elements Author(s) Demekhov, A. G. (RU)
Manninen, J. (FI)
Santolík, Ondřej (UFA-U) RID, ORCID
Titova, E. E. (RU)Number of authors 4 Source Title 2 nd URSI AT-RASC Proceedings. - Gent : URSI, 2018 Number of pages 1 s. Publication form Online - E Action URSI Atlantic Radio Science Meeting (AT-RASC) /2./ Event date 28.05.2018 - 01.06.2018 VEvent location Gran Canaria Country ES - Spain Event type WRD Language eng - English Country BE - Belgium Keywords magnetosphere ; VLF hiss emissions ; chorus emissions ; Van Allen Probes spacecraft ; EMFISIS Subject RIV BL - Plasma and Gas Discharge Physics OECD category Fluids and plasma physics (including surface physics) Institutional support UFA-U - RVO:68378289 Annotation We present the results of simultaneous observations [1] of VLF chorus elements at the ground-based station Kannuslehto in Northern Finland and on board Van Allen Probe A. Visual inspection and correlation analysis of the data reveal one-to-one correspondence of several (at least 12) chorus elements following each other in a seq uence. Poynting flux calculated from electromagnetic fields measured by the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument on board Van Allen Probe A shows that the waves propagated at small angles to the geomagnetic field and oppositely to its direction, that is, from northern to southern geographic hemisphere. The spacecraft was located at L ' 4.1 at a geomagnetic latitude of −12.4 degrees close to the plasmapause and inside a localized density inhomogeneity with about 30% density increase and a transverse size of about 600 km.
The observed waves are part of a long-lasting (about two hours) wave event including both chorus and hiss-like
emissions.
The time delay between the waves detected on the ground and on the spacecraft is about 1.3 s, with ground-based detection leading spacecraft detection. The measured time delay is consistent with the wave travel time of quasiparallel whistler-mode waves for a realistic profile of the plasma density distribution along the field line. Therefore, chorus wave packets were detected first at Kannuslehto on the ground, and then in 1.3 to 1.4 s they reached the Van Allen Probe A on the opposite side of the magnetic equator.
The results suggest that chorus discrete elements can preserve their spectral shape during a hop from the generation region to the ground followed by reflection from the ionosphere and return to the near-equatorial region.
Workplace Institute of Atmospheric Physics Contact Kateřina Adamovičová, adamovicova@ufa.cas.cz, Tel.: 272 016 012 ; Kateřina Potužníková, kaca@ufa.cas.cz, Tel.: 272 016 019 Year of Publishing 2019
Number of the records: 1