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Auroral heating of plasma patches due to high-latitude reconnection
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  • Joaquin Diaz Pena,
  • Joshua L. Semeter,
  • Yukitoshi (Toshi) Nishimura,
  • Roger Varney,
  • Ashton S Reimer,
  • Marc R. Hairston,
  • Matthew David Zettergren,
  • Michael Hirsch,
  • Olga P. Verkhoglyadova,
  • Keisuke Hosokawa,
  • Kazuo Shiokawa
Joaquin Diaz Pena
Boston University

Corresponding Author:[email protected]

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Joshua L. Semeter
Boston University
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Yukitoshi (Toshi) Nishimura
Boston University
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Roger Varney
SRI International
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Ashton S Reimer
SRI International
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Marc R. Hairston
University of Texas at Dallas
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Matthew David Zettergren
Embry-Riddle Aeronautical University
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Michael Hirsch
Boston University
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Olga P. Verkhoglyadova
Jet Propulsion Laboratory, California Institute of Technology
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Keisuke Hosokawa
University of Electro-Communications
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Kazuo Shiokawa
Institute for Space-Earth Environmental Research, Nagoya University
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Abstract

This study exploits the volumetric sampling capabilities of the Resolute Bay Incoherent Scatter Radar (RISR-N) in collaboration with all-sky imagery and in-situ measurements (DMSP) to examine the interplay between cold plasma transport and auroral precipitation during a high-latitude lobe reconnection event on the dawn side. The IMF had an impulsive negative excursion in B$_z$ embedded within a prolonged period of B$_z>0$ and B$_y<0$. The combined effects of transport and magnetic stress release associated with a reconnection pulse resulted in a co-mingling of plasma patches and soft electron precipitation, creating regions of elevated electron density and temperature. Altitude profiles of ionospheric parameters extracted in the rest frame of the drifting patch showed an increase in $T_e$ above 200 km and $N_e$ below 250 km (both hallmarks of soft precipitation), while also showing small and predictable changes in $N_e$ near the F-region peak over the 34-minute duration of the event. For the first time, we identified that the simultaneous appearance of elevated $T_e$ and elevated F-region $N_e$ (i.e., a ‘hot patch’), thus providing a new formation process for hot patches. The physics-based GEMINI model was used to explore the response to the observed precipitation as a function of altitude and time. Enhancements in $N_e$ in the topside ionosphere (e.g., DMSP altitudes) are caused by upward ambipolar diffusion induced by ionospheric heating and not impact ionization. The study highlights the importance of densely distributed measurements in space and time for understanding both mesoscale and small-scale ionospheric dynamics in regions subject to complex forcing.