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Swedish Institute of Space Physics (59°50.272′N, 17°38.786′E)
Student project at IRF Uppsala

Student Project (15 c)/Studentprojekt (15 hp)

Ionospheric irregularities: comparison of in-situ to Swepos data

Student: Oscar Suneson, Uppsala University
Supervisor: Stephan Buchert
Period: 2020


It has been shown that ionospheric irregularities can disturb our GNSS (Global Navigation Satellite System) communication. This disturbance is caused by scintillation of the radio signals when they pass through the ionosphere, leading to lock-on difficulties or in worst case, a loss of position for the GNSS-receiver. In this study, a large number of ground based GNSS reference stations spread across Sweden (known as the Swepos-network) was used to measure the variability of the GNSS-signal. These measurements were then combined with observations of ionospheric irregularities made by the Langmuir probes on ESA's SWARM satellites. The study is a collaboration between Uppsala University and the Swedish Institute of Space Physics and covers five events between December 2013 to Mars 2021, when both datasets were available. The purpose is to determine the shape and extension of these ionospheric irregularities and how localized in time and space they are. The study also tries to answer whether it is possible to draw any conclusions regarding physical models such as diffraction or refraction from this comparison. It was found that during the event days, there was in general a clear increase (of often several hundred percent) of the spatial variability on different scales according to the standard deviation. This increase was seen for both the lower orbiting SWARM A and C satellites and the higher orbiting SWARM B. It was also possible to see that the increase of spatial variability was spread across all the studied latitudes, (magnetic latitude 49deg to 70deg). This corresponds well with the fact that all the analysed event days had an GNSS-signal variability above average for the same latitudes. There seems to be a clear connection between increased GNSS-signal variability and ionospheric irregularities, although more studies need to be done to be able to draw more accurate conclusions.


Final report

[A CME as seen by STEREO A (NASA).]
The Swarm satellites, each carrying two IRF Uppsala Langmuir probes providing the in situ plasma density measurements used in this work.
last modified on Monday, 08-Nov-2021 12:02:30 CET