Seasonal influence on polar cap patches in the high-latitude nightside ionosphere

Wood, AG ORCID: 0000-0002-7527-4757 and Pryse, SE, 2010. Seasonal influence on polar cap patches in the high-latitude nightside ionosphere. Journal of Geophysical Research: Space Physics, 115 (A7), A07311. ISSN 0148-0227

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Abstract

The influence of the season on the patch-to-background density ratio of polar cap patches in the nightside ionosphere was observed above northern Scandinavia around solar maximum (1999–2001). This is the first study of the seasonal effect in the nightside polar ionosphere. The observations were conducted by the European Incoherent Scatter Svalbard Radar under conditions favorable for patches based on the high-latitude plasma convection pattern, the interplanetary magnetic field, and an absence of in situ precipitation. Patch-to-background ratios of up to 9.4 ± 2.9 were observed between midwinter and equinox, with values of up to 1.9 ± 0.2 in summer. As the patch-to-background ratios in summer were <2, the enhancements could not formally be called patches; however, these were significant density enhancements within the antisunward cross-polar flow. Aberystwyth University's PLASLIFE (PLASma LIFEtime) computer simulation was used to model the observed seasonal trend in the patch-to-background ratio and to establish reasons for the difference between winter and summer values. This difference was primarily attributed to variation in the chemical composition of the atmosphere, which, in summer, both reduced the electron densities of the plasma drawn into the polar cap on the dayside and enhanced plasma loss by recombination. A secondary factor was the maintenance of the background polar ionosphere by photoionization in summer.

Item Type: Journal article
Publication Title: Journal of Geophysical Research: Space Physics
Creators: Wood, A.G. and Pryse, S.E.
Publisher: American Geophysical Union
Date: 2010
Volume: 115
Number: A7
ISSN: 0148-0227
Identifiers:
NumberType
10.1029/2009JA014985DOI
Rights: Copyright 2010 by the American Geophysical Union.
Divisions: Schools > School of Science and Technology
Depositing User: Jill Tomkinson
Date Added: 04 Mar 2016 14:43
Last Modified: 09 Jun 2017 13:59
URI: http://irep.ntu.ac.uk/id/eprint/27093

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