Morphological response of GPS derived ionospheric scintillation activity to disturbed magnetic conditions in the European auroral sector

摘要

Radio signals propagating from artificial Earth orbiting satellites throughout the ionosphere may experience intensity and phase temporal fluctuations. Those fluctuations are due to irregularities in the spatial distribution of the ionospheric plasma density, traversed by the radio signals. At high latitudes, scintillations are observed in relation to ionospheric plasma density irregularities forming because of disturbed geomagnetic conditions. This is particularly true for GPS based observations at L band. Experimental data for the analysis of the scintillation activity were recorded by using a standard GSV4004 ionospheric monitor, where quiet and disturbed days during the measurement campaign were considered and compared in terms of scintillation indices, such as S_4, σ_Ф, SI, S_Ф, as well as the rate of change of the Total Electron Content (TEC). 50 Hz sampling raw intensity and phase data were used to (re-)calculate all those parameters by using different boundary conditions in the detrending process. As already shown analytically in the past, the systematic analysis of experimental data collected at European auroral latitudes confirm that the phase scintillation index σ_Ф may be confused with TEC fluctuations most of the time. A careful consideration of what is described by the classical phase scintillation index σ_Ф is then needed whn attempting to estimate scintillation activity at high latitudes.