Thermospheric wind response to driving forces in the vicinity of the Harang discontinuity

Stewart, R.D.; Rodger, Alan S.; Dudeney, John R.. 1988 Thermospheric wind response to driving forces in the vicinity of the Harang discontinuity. Planetary and Space Science, 36 (2). 225-229. 10.1016/0032-0633(88)90059-1

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Abstract/Summary

Fabry-Perot interferometer Doppler measurements of the 6300 Å oxygen emission line have been used to determine the neutral thermospheric wind over Halley, Antarctica. Simultaneous measurements of the local magnetic field have been used to generate a time frame with respect to the passage of the Harang discontinuity across the observing station. This identifies the night-time divergence in the dawn and dusk ion convection cells. Neutral wind measurements in this “Harang” time frame have shown a significantly higher degree of ordering than when considered in Universal Time. In particular, a reduction in the meridional component of the neutral wind is observed near the time of the discontinuity. This may be explained by a local reduction in Joule heating or through coupling to divergent convecting ions at the Harang discontinuity. The zonal component wind data show a marked transition from eastward to westward near 23:00 U.T., but there are no effects attributable to the Harang discontinuity. This transition arises because Halley moves from a regime where solar e.u.v. driven winds dominate to one where ion-drag is the most important driving force. This is supported by the dependence of the transition time on the level of local geomagnetic activity.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1016/0032-0633(88)90059-1
ISSN:	00320633
Date made live:	06 Dec 2018 09:23 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/521818

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