GPS navigators are now in common use, also because they are integrated into smartphones and cars. However, the position provided by navigators is not always reliable because the signal transmitted by GPS satellites can undergo malfunctions due to the turbulent conditions of the upper atmosphere.
Published in Scientific Reports, a journal of the Nature group, a study by the National Institute of Geophysics and Volcanology (INGV) entitled "The ionospheric irregularities climatology over Svalbard from solar cycle 23", dedicated to the disturbances induced on GPS signals by the ionosphere in the region arctic and caused by solar storms.
INGV holds the world record for the longest historical series of data acquired by a GPS signal receiver configured to study the formation of ionospheric irregularities which cause the effect known as "scintillation".
The receiver, located in the Svalbard Islands off the coast of Norway – 79°N latitude – is most sensitive to the effects of solar storms, where they are most effective in generating disturbances in the upper part of the atmosphere, jeopardizing satellite positioning and use of satellite-based navigation systems (GPS).
Given the growing need for increasingly accurate satellite positioning and the need to minimize the environmental impact of human activities, the study of scintillations at polar latitudes has become crucial in the field of space weather (so-called "space weather"). , which assists the reliability of the technology, with particular reference to the support to civil aviation.
The data have been available since the end of 2003 and have made it possible to study the probability of these disturbances throughout a solar cycle, i.e. along that span of time, approximately 11 years, during which the Sun manifests its great variety: from extreme quiet in periods of minimal solar activity to explosive phenomena that can affect the Earth in periods of maximum activity.
The possibility of being able to consider all types of phenomena originating from the Sun has made it possible to study where and when the GPS signal is deteriorated, in order to mitigate the risk of incorrect positioning for users.
picture 1 - Probability of GPS signal jamming as a function of latitude and time of day (in a magnetic reference) for different levels of solar disturbance (quiet conditions on the left, minor to moderate disturbance conditions in the centre, strong extreme right).
Furthermore, since the end of 2015, INGV has also been studying the signals emitted by the European constellation for satellite positioning called "Galileo", received in parallel by the receiver on the Svalbard Islands. Born from the agreement between the European Union and the European Space Agency (ESA), "Galileo" represents the possible alternative to GPS, owned by the US government
The study highlighted that, although GPS and Galileo are exposed to the same dangers, the European constellation appears to have a greater resistance to disturbances from the sun.
picture 2 - Comparison between the probability of jamming the GPS signal (left) and the Galileo signal (right) as a function of latitude and time of day (in a magnetic reference). The areas of high probability of disturbance are smaller for Galileo than for GPS.
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