Climatology of High and Low Latitude Scintillation in the Last Solar Cycle by Means of the Geodetic Detrending Technique

Abstract

Signals from a Global Navigation Satellite System (GNSS) can be disturbed along the propagation ray path from the satellites to the receivers. The presence of irregularities in the electron density in the near-Earth space environment can cause refraction and/or diffraction in the electromagnetic signals used by GNSS. This causes fast fluctuations of the GNSS signals known as scintillation. Currently, specialized Ionospheric Scintillation Monitoring Receivers (ISMRs) are used to characterize the intensity (or amplitude) and the phase scintillation. ISMRS are capable of sampling GNSS carrier-phase measurements at high-rate (e.g. 50 to 100 Hz) and must be equipped with a highly stable clock. In contrast, the present contribution studies the climatology of scintillation at high- and low- latitudes for both hemispheres and for a long temporal series, with measurements gathered by conventional geodetic receivers with a sampling frequency of 1 Hz that belong to the International GNSS Service (IGS) network. The derivation of S4 (amplitude scintillation) and ?? (phase scintillation) parameters uses a novel technique based in a precise Geodetic Detrending (GD) of the carrier-phase measurements, as in Precise Point Positioning (PPP). Amplitude and phase scintillation have been statistically characterized by means of the cumulative distribution functions (CDF) of S4 and ?? parameters. The thresholds for moderate and intense scintillation periods are established from the 99% and 99.9% percentiles of the CDFs as 0.25 and 0.45 for ?? values and 0.3 and 0.5 for S4 values, respectively. The large temporal series analyzed allows relating high-activity periods to severe space weather events such as geomagnetic storms at high-latitudes, to local times from 19h to midnight at low-latitudes and studying the seasonal dependencies. We conclude that the GD method is a powerful tool to perform scintillation studies and that it can be applied to individual (i.e. uncombined) signal frequencies.