The Empirical Canadian High Arctic Ionospheric Model (E-CHAIM) – NmF2 and hmF2


  1. Themens, D.R.
  2. McCaffrey, A.M.
  3. Jayachandran, P.T.
  4. Reid, B.
Corporate Authors
Defence Research and Development Canada, Ottawa Research Centre, Ottawa ON (CAN);New Brunswick Univ, Fredericton NB (CAN)
We present here the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM) quiet NmF2, perturbation NmF2, and quiet hmF2 models. These models provide peak ionospheric characteristics for a domain above 50°N geomagnetic latitude. Model fitting is undertaken using all available ionosonde and radio occultation electron density data, constituting a dataset of over 28 million observations. A comprehensive validation of the model is undertaken and performance is compared to that of the International Reference Ionosphere (IRI). In the case of the quiet NmF2 model, the E-CHAIM model provides a systematic improvement over the IRI URSI maps. At all stations within the polar cap, we see drastic RMS error improvements over the IRI by up to 1.3MHz in critical frequency (up to 60% in NmF2). These improvements occur primarily during equinox periods and at low solar activities, decreasing somewhat as one tends to lower latitudes. Qualitatively, the E-CHAIM is capable of representing auroral enhancements in NmF2, as well as the location and extent of the Main Ionospheric Trough (MIT), not reproduced by the IRI. The included NmF2 storm model demonstrates improvements over the IRI by up to 35% and over the quiet-time E-CHAIM model by up to 30%. In terms of hmF2, over the validation periods used in this study, we found overall RMS errors of ~13km for E-CHAIM, with IRI2007 overall hmF2 errors ranging between 16km and 22km. The E-CHAIM performs comparably to or slightly better than the IRI wi

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Canadian High Arctic Ionospheric Model;International Reference Ionosphere;High-Frequency
Report Number
DRDC-RDDC-2018-C195 — Contract Report
Date of publication
01 Jan 2019
Number of Pages
Electronic Document(PDF)

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