The relation between space geodetic measurements and ionosphere models is twofold: (1) the geodetic measurements can be evaluated to derive parameters of physical, empirical or analytical ionosphere models and (2) models are used to correct the electromagnetic signals for the 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.

Space geodetic techniques such as GNSS (ground- and satellite-based), DORIS, VLBI, satellite altimetry or the GPS radio occultation missions (e.g Formosat-3/COSMIC, TerraSAR-X, OCEANSAT2) 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. Accurate ionospheric estimates and retrievals based on these techniques may significantly improve our understanding on the physical and dynamic characteristics of electron density and space weather at various scales. Consequently, contributions on physical modeling of the ionosphere are highly appreciated. Recent sounding results, report on achieved improvements of the accuracy and of the spatio-temporal resolution of derived ionospheric parameters as well as theoretical studies that assess requirements for the accuracy of relevant parameters are also welcome.