The Ionosphere¶

Note that the TEC of the model ionosphere is currently hard coded to zero inside TTCal.

Refraction¶

The index of refraction of a cold, collisionless, and unmagnetized plasma is

$$n = \sqrt{1 - \frac{\omega_p^2}{\omega^2}},$$

where $\omega_p$ is the plasma frequency and $\omega = 2\pi\nu$ is the angular frequency of the incident radiation.

TTCal models the ionosphere as a single uniform spherical shell. That is it does not account for the fact that ionosphere has multiple layers or that the density can vary within a layer. However with this simplification the refraction off the inner and outer edges of the ionosphere can be calculated with a simple ray tracer (see the diagram below).

Figure 1. An illustration of the ray tracing procedure used by TTCal to model ionospheric refraction.

Absorption¶

Ionospheric absorption is not currently accounted for.