The field-aligned-current system of a sun-aligned arc over Resolute Bay

Tuesday, 16 December 2014: 10:50 AM
Gareth W Perry1, Hanna Dahlgren2,3, Michael J Nicolls4, Matthew D Zettergren5, Jean-Pierre St-Maurice1, Joshua L Semeter6, Keisuke Hosokawa7 and Kazuo Shiokawa8, (1)University of Saskatchewan, Saskatoon, SK, Canada, (2)KTH Royal Institute of Technology, Stockholm, Sweden, (3)University of Southampton, Southampton, United Kingdom, (4)SRI International Menlo Park, Menlo Park, CA, United States, (5)Embry-Riddle Aeronautical Univ, Daytona Beach, FL, United States, (6)Boston Univ, Boston, MA, United States, (7)University of Electro-Communications, Tokyo, Japan, (8)Nagoya University, Solar terrestrial Environment Laboratory, Nagoya, Japan
We report on the first imaging measurements of a field-aligned-current system associated with a sun-aligned arc over Resolute Bay, Canada. The plasma parameters of the dusk-to-dawn drifting arc and surrounding ionosphere are extracted using the volumetric imaging capabilities of the Resolute Bay Incoherent Scatter Radar – North (RISR–N). Multipoint, line-of-sight plasma drift measurements are used to construct an image of the field-aligned-current system of the arc. Overlaid with red-line and green-line optical data, the current system is shown to be consistent with what is expected of an arc; namely, an upward field-aligned-current lies within the optical body of the arc, and the corresponding downward current lies adjacent to the arc. In this event, the signature of the latter is identifiable by a zonally narrow and meridionally extended F-region plasma density trough of significant magnitude situated along the leading edge of the arc. The trough is sustained by a convolution of chemical recombination and current closure in the field-aligned-current system, and maintains its orientation and position on the leading edge of the arc for the duration of its transit through the RISR-N field-of-view.