Abstract
Auroral particle precipitation potentially plays a main role in
ionospheric plasma structuring. The impact of auroral particle
precipitation on plasma structuring is investigated using multi-point
measurements from scintillation receivers and all sky cameras from
Longyearbyen, Ny-Ålesund and Hornsund on Svalbard. This provides us with
the unique possibility of studying the spatial and temporal dynamics of
the aurora. Here we consider three case studies to investigate how
plasma structuring is related to different auroral forms. We demonstrate
that plasma structuring impacting the GNSS signals is largest at the
edges of auroral forms. Here we studied two stable arcs, two dynamic
auroral bands and a spiral. Specifically for arcs we find elevated phase
scintillation indices at the pole-ward edge of the aurora. This is
observed for auroral oxygen emissions (557.7 nm) at
150~km in the ionospheric E-region. This altitude is
also used as the ionospheric piercing point for the GNSS signals as the
observations remain the same regardless of different satellite
elevations and azimuths. Further, there may be a time delay between the
temporal evolution of aurora (f.e. commencement and fading of auroral
activity) and observations of elevated phase scintillation indices. The
time delay could be explained by the intense influx of particles, which
increases the plasma density and causes recombination to carry on
longer, which may lead to a persistence of structures - a ‘memory
effect’. High values of phase scintillation indices can be observed even
shortly after strong visible aurora and can then remain significant at
low intensities of the aurora.