Abstract
AbstractIonospheric scintillation occurs mainly at high and low latitude regions of the Earth and may impose serious degradation on GNSS (Global Navigation Satellite System) functionality. The Brazilian territory sits on one of the most affected areas of the globe, where the ionosphere behaves very unpredictably, with strong scintillation frequently occurring in the local postsunset hours. The correlation between scintillation occurrence and sharp variations in the ionospheric total electron content (TEC) in Brazil is demonstrated in Spogli et al. (2013). The compounded effect of these associated ionospheric disturbances on long baseline GNSS kinematic positioning is studied in this paper, in particular when ionospheric maps are used to aid the positioning solution. The experiments have been conducted using data from GNSS reference stations in Brazil. The use of a regional TEC map generated under the CALIBRA (Countering GNSS high‐Accuracy applications Limitations due to Ionospheric disturbances in BRAzil) project, referred to as CALIBRA TEC map (CTM), was compared to the use of the Global Ionosphere Map (GIM), provided by the International GNSS Service (IGS). Results show that the use of the CTM greatly improves the kinematic positioning solution as compared with that using the GIM, especially under disturbed ionospheric conditions. Additionally, different hypotheses were tested regarding the precision of the TEC values obtained from ionospheric maps, and its effect on the long baseline kinematic solution evaluated. Finally, this study compares two interpolation methods for ionospheric maps, namely, the Inverse Distance Weight and the Natural Neighbor.
Highlights
Global Navigation Satellite Systems (GNSS) have been used in support of various applications such as precision agriculture, offshore operations, geodesy, surveying, mapping, land management, construction, and so on
High-accuracy GNSS positioning is challenging in Brazil due to the frequent occurrence of scintillation and the rapid variations of total electron content (TEC) and due to the density of the available permanent GNSS networks, where the distance between stations can reach up to hundreds of kilometers, as, for example, in the São Paulo State based Real-Time Kinematic (RTK) network run by UNESP (São Paulo State University), the so-called URTKN (UNESP RTK Network)
CALIBRA (Countering GNSS high-Accuracy applications Limitations due to Ionospheric disturbances in BRAzil), a project cofunded by the GNSS Supervisory Authority (GSA) under the European Commission Seventh Framework Program (FP7), aimed to develop carrier phase-based high-accuracy algorithms for RTK and Network RTK (NRTK) that are able to counter the adverse effects of ionospheric scintillation and sharp TEC gradients in Brazil
Summary
Global Navigation Satellite Systems (GNSS) have been used in support of various applications such as precision agriculture, offshore operations, geodesy, surveying, mapping, land management, construction, and so on. High-accuracy GNSS positioning is challenging in Brazil due to the frequent occurrence of scintillation (characterized by rapid fluctuations in the amplitude and phase of transionospheric radio signals) and the rapid variations of total electron content (TEC) and due to the density of the available permanent GNSS networks, where the distance between stations can reach up to hundreds of kilometers, as, for example, in the São Paulo State based Real-Time Kinematic (RTK) network run by UNESP (São Paulo State University), the so-called URTKN (UNESP RTK Network) Despite these problems, GNSS is a highly demanding technique in Brazil where high-accuracy positioning is required in support of various applications such as precision agriculture, offshore, surveying, land management, civil aviation, and geodesy [Park et al, 2015]. Experiments presented in this paper have been carried out using data from two GNSS networks in Brazil, namely, the URTKN, made up of 11 stations established in the state of São Paulo, and the Ionospheric Scintillation Monitoring Receiver network made up of 10 stations covering the Brazilian territory, referred to as CIGALA (CIGALA Concept for Ionospheric Scintillation Mitigation for Professional GNSS in Latin America)-CALIBRA network
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