Ionospheric scintillation: investigation and evaluation in GNSS positioning

• Grant number: 12/16110-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2012
• End date: September 30, 2014
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geodesy
• Principal Investigator: Daniele Barroca Marra Alves
• Grantee: Jessica Saldanha Souza
• Host Institution: Faculdade de Ciências e Tecnologia (FCT). Universidade Estadual Paulista (UNESP). Campus de Presidente Prudente. Presidente Prudente , SP, Brazil
• Associated research grant: 06/04008-2 - GNSS: investigations and applications in geodetic positioning, in studies related to the atmosphere and precision agriculture, AP.TEM

Abstract

In order to study the effects caused on GNSS (Global Navigation Satellite System) signals the terrestrial atmosphere can be divided into the ionosphere and troposphere. The ionosphere has a great influence on GNSS propagation signals, it can cause degenerative effects in transmitted signals. The constitution of this region is related to incident solar rays on the terrestrial atmosphere and its behavior depends on local time, latitude, seasons, and solar activity. There are ionosphere irregularities that also affect the GNSS signal propagation, as ionospheric scintillation. The ionospheric scintillation can be described as a fast change in phase and amplitude of GNSS signal, caused by electron density irregularities. Scintillation can degrade or cause the GNSS signal lost. An initiative to study and analyze the ionospheric scintillation effects is the CIGALA (Concept for Ionospheric Scintillation Mitigation for Professional GNSS in Latin America) project (http://cigala.galileoic.org/). CIGALA project had the goal of analyzing the ionospheric scintillation, in order to understand the causes and study these effects to the scintillation modeling and to improve techniques to be implemented in GNSS receivers. Due to these described factors, one can say that the ionosphere can cause important effects on GNSS positioning. It can affect in an expressive way the coordinate accuracy obtained by different positioning methods. This research is intended to evaluate the ionosphere effect, in special the ionospheric scintillation, point positioning, and network-based positioning. In order to evaluate the days where the scintillation was more significant, it will be used a database from CIGALA project (http://200.145.185.118/cigala/index.php). Using these data it will be possible to obtain information about ionospheric scintillation in different GNSS stations in Brazil. It will be possible to correlate the data according to time, season, and other factors that can contribute to scintillation analysis. In 2013 must occur an intense solar activity, which can intensify the ionosphere effects, and consequently scintillation, mainly in Brazil region, where the scintillation index is already intense. Concluding, the period of this project realization is ideal to realize these kinds of research.(AU)