The relation between space geodetic measurements and ionosphere models is twofold: (1) the geodetic measurements can be evaluated to derive parameters of ionosphere models and (2) models are used to correct the electromagnetic signals for ionospheric effects. In other words ionospheric signals such as electron density or vertical total electron content are either the target functions or interpreted as disturbing signals. Geodetic observation techniques such as terrestrial and space-based GNSS, radio occultation, satellite altimetry, DORIS or VLBI can provide valuable information on the electron density. The potential for ionospheric sensing using these techniques has improved considerably over the last few years as a result of technological advances, larger ground networks and developments of appropriate models and algorithms.

Solar activity, driven by changing photospheric magnetic fields, manifests itself in changes of the Sun’s electromagnetic spectrum, flares, variable solar wind streams and coronal mass ejections and subsequently change the terrestrial ionospheric conditions. Analysing the physical processes of the Sun-Earth connections in detail based on state-of-the-art space and ground-based observations is thus of key importance for developing appropriate models of ionospheric disturbances.

In this session, contributions on physical, empirical or analytical ionosphere modeling including post-processing and (near) real-time approaches as well as studies on the combination of different observation techniques are appreciated. Related space weather investigations and developments on the physical description of the ionosphere/plasmasphere are also welcome. This includes all relevant processes of solar and heliospheric activity, comprising observations, data analysis and modelling.

Besides these topics also contributions to Working Groups od the International Association of Geodesy (IAG) are welcome.
Space weather effects on the ionosphere can also result in ionospheric scintillations which have a significant impact on satellite radio communication and navigation system performance. The main effects of scintillations on transionospheric radio system are signal loss and phase cycle slips, causing difficulties in the signal lock of receivers. The study group WG 4.3.5 “Ionosphere Scintillations” of IAG’s Sub-Commission 4 coordinates research on the climatology of ionospheric scintillations, namely its variation with latitude, season, local time, magnetic activity and solar cycle. The goal is to understand the primary sources of scintillations in order to develop models for forecasting scintillation events.

The IAG WG “Ionosphere Prediction” is involved in the development of ionosphere prediction algorithm/models based on the dependence of ionospheric characteristics on solar and magnetic conditions as well as on the region of the Earth. The main focus of the WG is to develop algorithms for estimating and forecasting ionospheric parameters worldwide based on data from geodetic observation systems, introduce physics-motivated functions into the ionospheric parameters estimation process, combine data from different sensors to improve the spatial and temporal resolution and sensitivity taking advantage of different sounding geometries and latency.