Use of Global and Regional Ionosphere Maps for Single-Frequency Precise Point Positioning A.Q. Le, C.C.J.M. Tiberius, H. van der Marel and N. Jakowski Abstract This paper compares global and regional ionosphere maps in different aspects, from vertical TEC and slant TEC in the range domain to their appli- cation in single-frequency Precise Point Positioning. Under quiet ionospheric conditions, the mean of the difference in vertical TEC between the global (GIM) and regional (SWACI) map, in Europe, was found to be less than 1 TECU, and the RMS generally in the order of 1–2 TECU. Both static data and kinematic (flight) data are analysed. Although being limited in its coverage for the moment, the real-time regional map SWACI (from DLR) provides promising results also with highly kinematic data. It is shown that for the dataset under investigation the SWACI map can bring the vertical positioning accuracy to the same level as the horizontal one, at 2–3 km (95% level). Keywords GPS · Precise Point Positioning (PPP) · Single-frequency · Ionosphere A.Q. Le Delft Institute of Earth Observation and Space Systems (DEOS), Delft University of Technology, The Netherlands C.C.J.M. Tiberius Delft Institute of Earth Observation and Space Systems (DEOS), Delft University of Technology, The Netherlands H. van der Marel Delft Institute of Earth Observation and Space Systems (DEOS), Delft University of Technology, The Netherlands N. Jakowski Institute of Communications and Navigation, German Aerospace Center (DLR), Germany 1 Introduction Precise Point Positioning (PPP) is a positioning tech- nique in which only a standalone receiver is used to achieve decimeter to centimeter level accuracy any- where on the world. Major error sources in standalone positioning, including satellite orbit and clock errors, ionosphere and troposphere delays, and site displace- ment effects, are accounted for by using corrections from an augmentation system on the basis of a global tracking network or a priori models. Correction prod- ucts can be obtained from publicly available sources, in particular the International GNSS Service (IGS). In our PPP implementation, position parameters are estimated recursively together with the ambiguities of the pre- cise carrier phase measurements in a filter known as the phase-adjusted pseudorange algorithm. This is a purely kinematic approach and well suited for cheap single-frequency receivers, with relatively fast conver- gence and easy to implement. For single-frequency PPP, the ionospheric delay is the most critical source of error. Global Ionosphere Maps (GIM) from the IGS are a popular product to compensate for the ionospheric delay. With the GIMs, Vertical Total Electron Content (VTEC) values are pro- vided with an accuracy of about 2–8 TECU every two hours on a 5 ◦ × 2.5 ◦ longitude and latitude grid with a latency of 1 day (Beutler et al., 1999). The remaining ionospheric error mainly affects the vertical position- ing component. Since mid 2004, regional ionosphere maps have been made available for Europe under the Space Weather Application Center – Ionosphere (SWACI) project. It is a joint project of the DLR Institute of Communications and Navigation (IKN) and the M.G. Sideris (ed.), Observing our Changing Earth, International Association of Geodesy Symposia 133, 759 c  Springer-Verlag Berlin Heidelberg 2009