A study of quasi-periodic ELF-VLF emissions at three Antarctic stations: evidence for off-equatorial generation?

Morrison, K.; Engebretson, M. J.; Beck, J. R.; Johnson, J. E.; Arnoldy, R. L.; Cahill, L. J.; Carpenter, D. L.; Gallani, M.. 1994 A study of quasi-periodic ELF-VLF emissions at three Antarctic stations: evidence for off-equatorial generation? Annales Geophysicae, 12 (2). 139-146. 10.1007/s00585-994-0139-8

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Official URL: http://dx.doi.org/10.1007/s00585-994-0139-8

Abstract/Summary

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.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1007/s00585-994-0139-8
Programmes:	BAS Programmes > Pre 2000 programme
ISSN:	1432-0576
Date made live:	29 Mar 2017 08:42 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/516689

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1007/s00585-994-0139-8

Programmes:

BAS Programmes > Pre 2000 programme

ISSN:

1432-0576

Date made live:

29 Mar 2017 08:42 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/516689