Journal ArticleDOI
Observations of an enhanced convection channel in the cusp ionosphere
Michael Pinnock,Alan S. Rodger,J. R. Dudeney,K. B. Baker,Patrick T. Newell,R. A. Greenwald,M. E. Greenspan +6 more
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In this paper, the authors describe combined observations by the PACE HF backscatter radar and the DMSP F9 polar-orbiting satellite of a transient velocity signature in the southern hemisphere ionospheric cusp.Abstract:
Transient or patchy magnetic field line merging on the dayside magnetopause, giving rise to flux transfer events (FTEs), is thought to play a significant role in energizing high-latitude ionospheric convection during periods of southward interplanetary magnetic field. Several transient velocity patterns in the cusp ionosphere have been presented as candidate FTE signatures. Instrument limitations, combined with uncertainties about the magnetopause processes causing individual velocity transients, mean that definitive observations of the ionospheric signature of FTEs have yet to be presented. This paper describes combined observations by the PACE HF backscatter radar and the DMSP F9 polar-orbiting satellite of a transient velocity signature in the southern hemisphere ionospheric cusp. The prevailing solar wind conditions suggest that it is the result of enhanced magnetic merging at the magnetopause. The satellite particle precipitation data associated with the transient are typically cusplike in nature. The presence of spatially discrete patches of accelerated ions at the equatorward edge of the cusp is consistent with the ion acceleration that could occur with merging. The combined radar line-of-sight velocity data and the satellite transverse plasma drift data are consistent with a channel of enhanced convection superposed on the ambient cusp plasma flow. This channel is at least 900 km in longitudinal extent but only 100 km wide. It is zonally aligned for most of its extent, except at the western limit where it rotates sharply poleward. Weak return flow is observed outside the channel. These observations are compared with and contrasted to similar events seen by the EISCAT radar and by optical instruments.read more
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Journal ArticleDOI
Magnetospheric sources of Pc1-2 ULF waves observed in the polar ionospheric waveguide
TL;DR: In this article, a magnetometer array operated during the Antarctic winter observed Ultra-Low-Frequency (LJLF) plasmawaves in the Pc 1-2 (0.1-10.0 Hz) frequency range, propagating parallel to the surface of the Earth in a waveguide or duct centred at -300 km altitude in the ionosphere.
Journal ArticleDOI
Observations of an enhanced convection flow channel for northward turning IMF
TL;DR: In this article, a detailed case study of the excitation of a more than 200 km wide flow channel with ionospheric drift speeds exceeding 2 kms−1 is presented.
Book ChapterDOI
Ionospheric Signatures of Magnetopause Processes
TL;DR: In this paper, the authors describe some of the problems involved in the interpretation of dayside transient features, all of which result from time-and spatially-varying field-aligned currents.
Journal ArticleDOI
Do the dayside cusps blink
TL;DR: The polar cusp is a region of the ionosphere for which magnetosheath plasma can be observed as mentioned in this paper, and the low-altitude particle cusp region is the region of ionosphere that can be seen from the Earth's magnetic field.
Journal Article
Inverse Energy Dispersion of Energetic Ions Observed in the Magnetosheath
S. H. Lee,David G. Sibeck,Kyoung-Joo Hwang,Y. Wang,M. V. D. Silveira,Mei-Ching Fok,Barry Mauk,Cohen J. Ian,Mike Ruohoniemi,Naritoshi Kitamura,James L. Burch,Barbara L. Giles,Roy B. Torbert,Christopher T. Russell,M. Lester +14 more
References
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Journal ArticleDOI
Empirical high-latitude electric field models
J. P. Heppner,N. C. Maynard +1 more
TL;DR: In this paper, large-scale revisions of the OGO 6 dawn-dusk measurement models are made, showing that the deformations of the two-cell patterns lead to sunward convection in dayside polar regions, while maintaining the integrity of the night-side convection pattern.
Journal ArticleDOI
The cusp and the cleft/boundary layer: Low-altitude identification and statistical local time variation
Patrick T. Newell,Ching-I. Meng +1 more
TL;DR: In this paper, the authors investigated the distinction between the low-altitude cusp and the cleft (with the latter identified as the ionospheric signature of low-latitude boundary layer (LLBL)) on both a statistical and a case study basis.
Journal ArticleDOI
Ionospheric traveling convection vortices observed near the polar cleft: A triggered response to sudden changes in the solar wind
TL;DR: In this paper, the signatures of localized ionospheric traveling convection vortices were analyzed using 20-second resolution magnetometer data from an array of temporary stations operated around Sondre Stromfjord, Greenland during the summer of 1986.
Journal ArticleDOI
What are flux transfer events
TL;DR: In this paper, the authors argue that surges in the reconnection rate on the magnetopause give rise to bubble-like regions of plasma containing a twisted field with energetic streaming particles in the outer layers.
Journal ArticleDOI
Magnetic flux transfer at the magnetopause based on single X line bursty reconnection
TL;DR: In this paper, a model of flux transfer events at the dayside magnetopause is proposed, which is based on non-stationary reconnection along a single X line over a large longitudinal segment.