Ionospheric scintillation originates from the scattering of electromagnetic waves through spatial gradients in the plasma density distribution, drifting across a given propagation direction. Ionospheric scintillation represents a disruptive manifestation of adverse space weather conditions through degradation of the reliability and continuity of satellite telecommunication and navigation systems and services (e.g. EGNOS). The purpose of the experiment presented here was to determine the contribution of auroral ionisation structures to GPS scintillation. EISCAT measurements were obtained along the same line of sight of a given GPS satellite observed from Tromso and followed by means of the ESCAT UHF radar to causally identify plasma structures that give rise to scintillation on the co-aligned GPS radio link. Large-scale structures associated with the northern edge of the ionospheric trough, with auroral arcs in the nightside auroral oval and with particle precipitation at the onset of a substorm were indeed identified as responsible for enhanced phase scintillation at L band. For the first time it was observed that the observed large-scale structures did not cascade into smaller-scale structures, leading to enhanced phase scintillation without amplitude scintillation. More measurements and theory are necessary to understand the mechanism responsible for the inhibition of large-to-small scale energy cascade and to reproduce the observations. This aspect is fundamental to model the scattering of radio waves propagating through these ionisation structures. New insights from this experiment allow a better characterisation of the impact that space weather can have on satellite telecommunications and navigation services.
©2016. The Authors.
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