Journal ArticleDOI
A study of quasi-periodic ELF-VLF emissions at three Antarctic stations: evidence for off-equatorial generation?
K. Morrison,Mark J. Engebretson,J. R. Beck,J. E. Johnson,Roger L. Arnoldy,Laurence J. Cahill,D. L. Carpenter,M. Gallani +7 more
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TLDR
In this article, the spatial extent and temporal behaviour of quasi-periodic (QP) intensity modulations of 0.5-2 kHz ELF-VLF signals were investigated in a comparative study of data collected at the Antarctic stations of South Pole (L=14), Halley (L =4), and Siple(L=4).Abstract:
The spatial extent and temporal behaviour of quasi-periodic (QP) intensity modulations of 0.5-2 kHz ELF-VLF signals were investigated in a comparative study of data collected at the Antarctic stations of South Pole (L=14), Halley (L=4), and Siple (L=4). Frequently, the waveforms of ELF-VLF signals simultaneously received at each site were identical. Although of similar frequency structure, the waveforms of the accompanying Pc3 magnetic pulsations did not show a one-to-one association. Whereas both are dayside phenomena, QP emissions occur over a smaller range of local times, and have a maximum of occurrence later in the day closer to local noon. QP emissions are identified with the periodic modulation of the electron pitch-angle distribution by the propagation of ULF compressional fast-mode waves through a region. However, contrary to previous ideas, rising-tone emissions do not represent the frequency-time signatures of such waves. In addition to generation close to the equatorial plane, we propose an additional high-latitude source of QP emissions. These emissions are associated with regions of minimum B produced by the dayside compression of the magnetosphere close to the magnetopause. Model magnetic field calculations of these minimum-B regions as a function of magnetic local time and invariant latitude are presented.read more
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Journal ArticleDOI
The numerical simulation of VLF chorus and discrete emissions observed on the Geotail satellite using a Vlasov code
TL;DR: In this article, the authors used a VHS Vlasov simulation code to model VLF chorus elements observed omn the Geotail satellite, which passes the equator at 10 earth radii.
Journal ArticleDOI
Periodic and quasiperiodic ELF/VLF emissions observed by an array of Antarctic stations
TL;DR: In this article, amplitude modulations in the frequency range 0-500 mHz of ELF/VLF (0.5-4.0 kHz) were recorded at Halley and South Pole stations, Antarctica.
Journal ArticleDOI
Latitudinal and seasonal variations of quasiperiodic and periodic VLF emissions in the outer magnetosphere
Mark J. Engebretson,J. L. Posch,Alexa Halford,Alexa Halford,G. A. Shelburne,Andrew Smith,Maria Spasojevic,Umran S. Inan,Roger L. Arnoldy +8 more
TL;DR: In this article, the authors analyzed ELF-VLF receiver and search coil magnetometer data from five Antarctic stations from 1998 and 1999 to study quasiperiodic emissions (QPs) and periodic emissions (PEs), which occur as ULF-range modulations of ELFVLF signals between 0.5 kHz and similar to 4 kHz.
Journal ArticleDOI
Quasiperiodic emissions observed by the Cluster spacecraft and their association with ULF magnetic pulsations
František Němec,Ondrej Santolik,Ondrej Santolik,Jolene S. Pickett,Michel Parrot,N. Cornilleau-Wehrlin +5 more
TL;DR: Němec et al. as discussed by the authors presented results of a survey of QP emissions observed by the Wide Band Data (WBD) instruments on board the Cluster spacecraft.
Journal ArticleDOI
Conjugate observations of quasi-periodic emissions by Cluster and DEMETER spacecraft
František Němec,Ondrej Santolik,Ondrej Santolik,Michel Parrot,Jolene S. Pickett,M. Hayosh,N. Cornilleau-Wehrlin +6 more
TL;DR: In this paper, a case study of a large-scale long-lasting quasi-periodic (QP) event observed simultaneously on board the DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) and the Cluster spacecraft is presented.