CEDAR email: Empirical Canadian High Arctic Ionospheric Model (E-CHAIM) released

Jayachandran Thayyil jaya at unb.ca
Wed Nov 7 07:25:19 MST 2018

We are pleased to announce that the University of New Brunswick Radio Physics Lab has completed the development of the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM) and has released the model for scientific use at https://e-chaim.chain-project.net. E-CHAIM is an empirical model of high-latitude electron density, intended as an alternative to the current International Standards Organization (ISO) recognized ionospheric standard, the International Reference Ionosphere (IRI), for applications at or above 50N geomagnetic latitude. The model features versions in Matlab, IDL, and C, with a Python interface under development. The model also features a daily-updated database of geomagnetic (AE, ap, Kp, Dst, PC, etc.) and solar indices (Rz, F10.7, etc.) that can be used as a stand-alone reference. This database is readily available for users at the E-CHAIM website.

The E-CHAIM parameterization is described in detail in Themens et al. [2017] and [2018]. The model applies a new approach to modeling the bottomside that avoids the need for a piece-wise approach, features an update to the IRI and NeQuick’s topside function, and is capable of resolving large-scale high-latitude features, such as the Main Ionospheric Trough (MIT) and the reduced altitude of the ionosphere in the auroral oval, that are not resolved by current standards. The model profiles and spatial variability are explicitly doubly differentiable, analytically differentiable, and continuous, making the model basis ideal for application in data assimilation frameworks.

Additional features, such as functions for producing the analytically-derived derivatives of the model parameters and functions to generate maps of the E-CHAIM fitting errors, are under development and will be released as we build on user feedback over the coming year.

E-CHAIM was funded under the Defence Research and Development Canada (DRDC)’s All Domain Situational Awareness Program.


Themens, D.R., et al. (2018). Topside Electron Density Representations for Middle and High Latitudes: A Topside Parameterization for E-CHAIM based on the NeQuick, J. Geophys. Res. Space Physics, 123, doi: 10.1002/2017JA024817.

Themens, D.R., P.T. Jayachandran, I. Galkin, and C. Hall (2017). The Empirical Canadian High Arctic Ionospheric Model (E-CHAIM): NmF2 and hmF2, J. Geophys. Res. Space Physics, doi: 10.1002/2017JA024398.

Dr. P. T. Jayachandran
Physics Department
University of New Brunswick
PO Box 4400, 8 Bailey Drive
Fredericton,  NB
Canada   E3B 5A3
Ph: 506-447-3330
Fax: 506-453-4581
Email: jaya at unb.ca<mailto:jaya at unb.ca>

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