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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 26, issue 6
Ann. Geophys., 26, 1641–1652, 2008
© Author(s) 2008. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 26, 1641–1652, 2008
© Author(s) 2008. This work is distributed under
the Creative Commons Attribution 3.0 License.

  11 Jun 2008

11 Jun 2008

Iterative inversion of global magnetospheric ion distributions using energetic neutral atom (ENA) images recorded by the NUADU/TC2 instrument

L. Lu1, S. McKenna-Lawlor2, S. Barabash3, K. Kudela4, J. Balaz2,4, I. Strharsky2,4, Z. X. Liu1, C. Shen1, J. B. Cao1, P. C. Brandt5, C. L. Tang6, and I. Dandouras7 L. Lu et al.
  • 1Centre for Space Science and Applied Research of the Chinese Academy of Sciences, Beijing, China
  • 2Space Technology Ireland, National University of Ireland, Maynooth, Co. Kildare, Ireland
  • 3Swedish Institute of Space Physics, Kiruna, Sweden
  • 4Institute of Experimental Physics, Kosice, Slovakia
  • 5The Johns Hopkins University Applied Physics Laboratory, Laurel MD, USA
  • 6School of Earth and Space Sciences, University of Science and Technology of China, Hefei, China
  • 7Centre d'Etude Spatiale des Rayonnements, Toulouse, France

Abstract. A method has been developed for extracting magnetospheric ion distributions from Energetic Neutral Atom (ENA) measurements made by the NUADU instrument on the TC-2 spacecraft. Based on a constrained linear inversion, this iterative technique is suitable for use in the case of an ENA image measurement, featuring a sharply peaked spatial distribution. The method allows for magnetospheric ion distributions to be extracted from a low-count ENA image recorded over a short integration time (5 min). The technique is demonstrated through its application to a set of representative ENA images recorded in energy Channel~2 (hydrogen: 50–81 keV, oxygen: 138–185 keV) of the NUADU instrument during a geomagnetic storm. It is demonstrated that this inversion method provides a useful tool for extracting ion distribution information from ENA data that are characterized by high temporal and spatial resolution. The recovered ENA images obtained from inverted ion fluxes match most effectively the measurements made at maximum ENA intensity.

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