Technical note | A Parametric Model of the Ionospheric Electron Density Profile for JORN

Abstract

To model the ionosphere, the Jindalee Operational Radar Network (JORN) uses a simple parametric description of the electron density profile at a large spatial grid of points. This technical note describes how to interpret those parameters to produce an electron density profile at any place and time by defining the ten parameters in use, and the rules used to construct six quasi-parabolic segments (QPS) that combine to produce a robust, complete, and flexible representation of the overhead electron density profile, eN(z). The basic model represents arbitrary shapes for three ionospheric layers (the E, F1 and F2 layers) and simple rules to characterise and quantify quasi-parabolic joining segments between each of the layers. These rules introduce the idea of the tenth ionospheric parameter F1q that controls the 'strength' of the F1 cusp between the F1 and F2 layers in addition to the three traditional ionospheric parameters (critical frequency, height of maximum electron density and semi-thickness of layer) describing each of the three layers. These extra joining segments are required to produce a continuous and smooth eN profile.

Executive Summary

To model the ionosphere, the Jindalee Operational Radar Network (JORN) uses a simple parametric description of the overhead ionosphere’s electron density profile at a large spatial grid of points. This note describes how to interpret those parameters in order to produce an electron density profile at any place and time. This report defines the ten parameters in use and explains the 6QPS profile rules used to provide a robust, complete and flexible representation of the overhead electron density profile. This is an inherent part of the JORN real-time ionospheric model (RTIM).

The basic model represents arbitrary quasi-parabolic shapes for three ionospheric layers (the E, F1 and F2 layers) and simple rules to characterise and quantify quasi-parabolic joining segments between each of the layers. These simple rules introduce the idea of the tenth ionospheric parameter F1q that controls the "strength" of the F1 cusp between the F1 and F2 traces, in addition to the three traditional ionospheric parameters (critical frequency, height of maximum electron density and semi-thickness of layer) describing each of the three layers. The extra joining segments are required to always produce a continuous and smooth electron density profile eN(z).

The report also shows how the simple model can be readily expanded to include the effects of multiple sporadic E layers in the ionosphere.

Numerous examples are presented to confirm that these 6QPS profile rules have the flexibility and robustness to represent vertical incidence sounder (VIS) traces accurately, both under a range of typical conditions and also during more