Scintillation measurements at Bahir Dar during the high solar activity phase of solar cycle 24

Abstract

Small scale ionospheric disturbances may cause severe radio scintillations of signals transmitted from global navigation satellite systems (GNSS). Consequently, small scale plasma irregularities may heavily degrade the performance of current GNSS such as GPS, Glonass or Galileo. The talk presents analysis results obtained primarily from two high-rate GNSS receiver stations (MSBD 01 /02) operated by the German Aerospace Center (DLR) in cooperation with the Bahir Dar University (BDU) at 11.6°N; 37.4°E. The station collects up to 50 Hz sampled raw data from which characteristic scintillation parameters such as the S4 index are deduced. The MSBD 01 receiver enables considering GPS L1, L2, and L5, GLONASS L1 and L2, and Galileo E1 and E5a frequencies since 2013. The analysis results indicate a seasonal dependence of the scintillation index with maxima around equinoxes. The scintillation index S4 may reach values up to S4=1 during sunset hours. Although the frequency range of the signals mentioned above is rather small, a frequency dependence of the scintillation strength can be deduced from the measurements. Further data analyses consider the detection of ionospheric bubbles in relation to enhanced scintillation activity and correlation studies with the MSBD 02 receiver located in the vicinity of the station mentioned above. Due to the simultaneous availability of GPS, Glonass and Galileo Systems a first attempt is made to generate scintillation maps based on ROTI and S4 measurements over the East African area.