Precise information of the 3-D ionospheric profiles is essential for accurate ray tracing and for estimating ionospheric effects on navigational and communication systems. Applications include radio communication, OTH radar, emitter location, missile, satellite trajectories and orbits, radio astronomical effects, and altimeters.

Statistical and/or physical models of the ionosphere do not provide accurate ionospheric profiles.

Data-driven models provide some improvements, but they have to assume ionospheric shape and height profiles.

Conventional ground-based tomography does not reproduce the ionospheric height well. There are fundamental problems related to limited view angles. GPS-based tomography is insensitive towards plasmaspheric contribution.