Topside Electron Density Representations for Middle and High Latitudes: A Topside Parameterization for E-CHAIM Based On the NeQuick

David R. Themens*, P. T. Jayachandran, Dieter Bilitza, Philip J. Erickson, Ingemar Häggström, Mykhaylo V. Lyashenko, Benjamin Reid, Roger H. Varney, Ljubov Pustovalova

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


In this study, we present a topside model representation to be used by the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM). In the process of this, we also present a comprehensive evaluation of the NeQuick's, and by extension the International Reference Ionosphere's, topside electron density model for middle and high latitudes in the Northern Hemisphere. Using data gathered from all available incoherent scatter radars, topside sounders, and Global Navigation Satellite System Radio Occultation satellites, we show that the current NeQuick parameterization suboptimally represents the shape of the topside electron density profile at these latitudes and performs poorly in the representation of seasonal and solar cycle variations of the topside scale thickness. Despite this, the simple, one variable, NeQuick model is a powerful tool for modeling the topside ionosphere. By refitting the parameters that define the maximum topside scale thickness and the rate of increase of the scale height within the NeQuick topside model function, r and g, respectively, and refitting the model's parameterization of the scale height at the F region peak, H0, we find considerable improvement in the NeQuick's ability to represent the topside shape and behavior. Building on these results, we present a new topside model extension of the E-CHAIM based on the revised NeQuick function. Overall, root-mean-square errors in topside electron density are improved over the traditional International Reference Ionosphere/NeQuick topside by 31% for a new NeQuick parameterization and by 36% for a newly proposed topside for E-CHAIM.

Original languageEnglish
Pages (from-to)1603-1617
Number of pages15
JournalJournal of Geophysical Research: Space Physics
Issue number2
Early online date14 Feb 2018
Publication statusPublished - 15 Mar 2018


  • empirical modeling
  • high latitude
  • ionosphere
  • NeQuick
  • topside

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology


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