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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 36, issue 1 | Copyright
Ann. Geophys., 36, 125-138, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Regular paper 25 Jan 2018

Regular paper | 25 Jan 2018

Modelling the main ionospheric trough using the Electron Density Assimilative Model (EDAM) with assimilated GPS TEC

James A. D. Parker1, S. Eleri Pryse1, Natasha Jackson-Booth2, and Rachel A. Buckland2 James A. D. Parker et al.
  • 1Department of Physics, Aberystwyth University, Aberystwyth, SY23 3BZ, UK
  • 2QinetiQ, Malvern, WR14 3PS, UK

Abstract. The main ionospheric trough is a large-scale spatial depletion in the electron density distribution at the interface between the high- and mid-latitude ionosphere. In western Europe it appears in early evening, progresses equatorward during the night, and retreats rapidly poleward at dawn. It exhibits substantial day-to-day variability and under conditions of increased geomagnetic activity it moves progressively to lower latitudes. Steep gradients on the trough-walls on either side of the trough minimum, and their variability, can cause problems for radio applications. Numerous studies have sought to characterize and quantify the trough behaviour.

The Electron Density Assimilative Model (EDAM) models the ionosphere on a global scale. It assimilates observations into a background ionosphere, the International Reference Ionosphere 2007 (IRI2007), to provide a full 3-D representation of the ionospheric plasma distribution at specified times and days. This current investigation studied the capability of EDAM to model the ionosphere in the region of the main trough. Total electron content (TEC) measurements from 46 GPS stations in western Europe from September to December 2002 were assimilated into EDAM to provide a model of the ionosphere in the trough region. Vertical electron content profiles through the model revealed the trough and the detail of its structure. Statistical results are presented of the latitude of the trough minimum, TEC at the minimum and of other defined parameters that characterize the trough structure. The results are compared with previous observations made with the Navy Ionospheric Monitoring System (NIMS), and reveal the potential of EDAM to model the large-scale structure of the ionosphere.

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Short summary
A study was conducted on the main ionospheric trough using the Electron Density Assimilative Model (EDAM). The idea was to compare results of the feature by using GPS data to results from a different method conducted in the past. The results showed that using GPS assimilated data, the feature could be modeled effectively when compared to the previous method, which shows the capability and potential of the model to study ionospheric features. This was the main purpose behind the research.
A study was conducted on the main ionospheric trough using the Electron Density Assimilative...