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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 28, issue 2 | Copyright
Ann. Geophys., 28, 651-664, 2010
https://doi.org/10.5194/angeo-28-651-2010
© Author(s) 2010. This work is distributed under
the Creative Commons Attribution 3.0 License.

  25 Feb 2010

25 Feb 2010

Dynamic variability in F-region ionospheric composition at auroral arc boundaries

M. Zettergren1,*, J. Semeter2, B. Burnett2, W. Oliver2, C. Heinselman3, P.-L. Blelly4, and M. Diaz5 M. Zettergren et al.
  • 1Physical Sciences Department, Embry-Riddle Aeronautical University, Daytona Beach, FL, USA
  • 2Department of Electrical and Computer Engineering and Center for Space Physics, Boston University, Boston, MA, USA
  • 3SRI International, Menlo Park, CA, USA
  • 4CESR, Toulouse, France
  • 5Electrical Engineering Dept., College of Engineering, University of Chile, Santiago, Chile
  • *formerly at: Department of Electrical and Computer Engineering and Center for Space Physics, Boston University, Boston, MA, USA

Abstract. The work presents a data-model synthesis examining the response of the auroral F-region ion temperature, composition, and density to short time scale (<1 min) electric field disturbances associated with auroral arcs. Ion temperature profiles recorded by the Sondrestrom incoherent scatter radar (ISR) are critically analyzed with the aid of theoretical calculations to infer ion composition variability. The analyses presented include a partial accounting for the effects of neutral winds on frictional heating and show promise as the groundwork for future attempts to address ion temperature-mass ambiguities in short-integration ISR data sets. Results indicate that large NO+ enchancements in the F-region can occur in as little as 20 s in response to impulsive changes in ion frictional heating. Enhancements in molecular ion density result in recombination and a depletion in plasma, which is shown to occur on time scales of several minutes. This depletion process, thus, appears to be of comparable importance to electrodynamic evacuation processes in producing auroral arc-related plasma depletions. Furthermore, the potential of ionospheric composition in regulating the amounts and types of ions supplied to the magnetosphere is outlined.

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