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On determining the noon polar cap boundary from SuperDARN HF radar backscatter characteristics

Pinnock, M.; Rodger, A.S.. 2001 On determining the noon polar cap boundary from SuperDARN HF radar backscatter characteristics. Annales Geophysicae, 18 (12). 1523-1530. 10.1007/s00585-001-1523-2

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Abstract/Summary

Previous work has shown that ionospheric HF radar backscatter in the noon sector can be used to locate the footprint of the magnetospheric cusp particle precipitation. This has enabled the radar data to be used as a proxy for the location of the polar cap boundary, and hence measure the flow of plasma across it to derive the reconnection electric field in the ionosphere. This work used only single radar data sets with a field of view limited to ∼2 h of local time. In this case study using four of the SuperDARN radars, we examine the boundary determined over 6 h of magnetic local time around the noon sector and its relationship to the convection pattern. The variation with longitude of the latitude of the radar scatter with cusp characteristics shows a bay-like feature. It is shown that this feature is shaped by the variation with longitude of the poleward flow component of the ionospheric plasma and may be understood in terms of cusp ion time-of-flight effects. Using this interpretation, we derive the time-of-flight of the cusp ions and find that it is consistent with approximately 1 keV ions injected from a subsolar reconnection site. A method for deriving a more accurate estimate of the location of the open-closed field line boundary from HF radar data is described.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1007/s00585-001-1523-2
Programmes: BAS Programmes > Antarctic Science in the Global Context (2000-2005) > Magnetic Reconnection, Substorms and their Consequences
ISSN: 0992-7689
Additional Keywords: Ionosphere (ionosphere-magnetosphere interactions, plasma convection) Magnetospheric physics (magnetopause, cusp, and boundary layers)
Date made live: 01 Nov 2012 14:12
URI: http://nora.nerc.ac.uk/id/eprint/20191

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