Climatology of high-latitude ionospheric scintillation based on 38.2 MHz IRIS riometer measurements in Northern Finland

Abstract:

Dynamic electron density irregularities, ranging in scale sizes from hundreds of kilometres to a few centimetres, cause scintillation of radio-waves propagating through the ionosphere. They can significantly reduce performance of GNSS (Global Navigation Satellite System) receivers and other positioning systems of varying frequencies. The high latitude ionosphere becomes very disturbed during geomagnetic storms due to auroral precipitation and motion of polar patches. While the scintillation topic is researched heavily at GPS frequencies, relatively little work has been done at MHz frequencies.
A rather unconventional approach has been taken, by using data from the IRIS riometer (Imaging Riometer for Ionospheric Studies), based in Kilspisjärvi, Finland (69.05° N 20.79° E). By observing the strong and homogeneous radio source Cassiopeia A, passing through multiple narrow beams, amplitude scintillations can be observed. The continuous dataset of approximately 14 years (1995 – 2009) was used to create climatological scintillation trends, presenting diurnal, seasonal and yearly variations of amplitude scintillation index, S­­­­₄. The correlation between S₄ index and geomagnetic indices (K_p, AE) was investigated and linear relationships were found.