Ionosonde measurements of dynamic characteristics and inhomogeneities of the ionosphere

Advanced models of the ionosphere, including the well-known International Reference Ionosphere (IRI) model, make use of various ionospheric characteristics, such as the critical frequency (f
o
F
2
), peak density height (h
m
F
2
), and total electron content (TEC), on which to base the construction of the vertical distribution profile of the ion and electron density. These variables are often used to either build (climatological) models or their measurements are ingested in real-time for nowcasting applications. However, only static, local characteristics are currently being used. In order to improve the ionospheric plasma specification and to provide more accurate nowcasts and forecasts, an improved knowledge of dynamic parameters like plasma drift velocities, asymmetries and gradients in the ionosphere is needed. This is particularly important when modelling the disturbed ionosphere, as strong gradients and large plasma movements can be expected to occur during geomagnetic storms.