Postmidnight ionospheric troughs in summer at high latitudes

M. Voiculescu, T. Nygrén, A. T. Aikio, H. Vanhamäki, V. Pierrard

    研究成果: ジャーナルへの寄稿学術誌査読

    15 被引用数 (Scopus)

    抄録

    In this article we identify possible mechanisms for the formation of postmidnight ionospheric troughs during summer, in sunlit plasma. Four events were identified in measurements of European Incoherent Scatter and ESR radars during CP3 experiments, when the ionosphere was scanned in a meridional plan. The spatial and temporal variation of plasma density, ion, and electron temperatures were analyzed for each of the four events. Super Dual Auroral Radar Network plasma velocity measurements were added, when these were available. For all high-latitude troughs the ion temperatures are high at density minima (within the trough), at places where the convection plasma velocity is eastward and high. There is no significant change in electron temperature inside the trough, regardless of its temporal evolution. We find that troughs in sunlit plasma form in two steps: the trough starts to form when energetic electron precipitation leads to faster recombination in the F region, and it deepens when entering a region with high eastward flow, producing frictional heating and further depleting the plasma. The high-latitude plasma convection plays an important role in formation and evolution of troughs in the postmidnight sector in sunlit plasma. During one event a second trough is identified at midlatitudes, with different characteristics, which is most likely produced by a rapid subauroral ion drift in the premidnight sector.

    本文言語英語
    ページ(範囲)12,171-12,185
    ジャーナルJournal of Geophysical Research: Space Physics
    121
    12
    DOI
    出版ステータス出版済み - 12月 1 2016

    !!!All Science Journal Classification (ASJC) codes

    • 宇宙惑星科学
    • 地球物理学

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