Abstract
Abstract. Small-scale ionospheric disturbances may cause severe radio scintillations of signals transmitted from global navigation satellite systems (GNSSs). Consequently, small-scale plasma irregularities may heavily degrade the performance of current GNSSs such as GPS, GLONASS or Galileo. This paper presents analysis results obtained primarily from two high-rate GNSS receiver stations designed and operated by the German Aerospace Center (DLR) in cooperation with Bahir Dar University (BDU) at 11.6° N, 37.4° E. Both receivers collect raw data sampled at up to 50 Hz, from which characteristic scintillation parameters such as the S4 index are deduced. This paper gives a first overview of the measurement set-up and the observed scintillation events over Bahir Dar in 2015. Both stations are located close to one another and aligned in an east–west, direction which allows us to estimate the zonal drift velocity and spatial dimension of equatorial ionospheric plasma irregularities. Therefore, the lag times of moving electron density irregularities and scintillation patterns are derived by applying cross-correlation analysis to high-rate measurements of the slant total electron content (sTEC) along radio links between a GPS satellite and both receivers and to the associated signal power, respectively. Finally, the drift velocity is derived from the estimated lag time, taking into account the geometric constellation of both receiving antennas and the observed GPS satellites.
Highlights
It is generally agreed that localized depletions of the lowlatitude F region electron density may be generated due to the Rayleigh–Taylor plasma instability after sunset (Kelley, 2009)
This paper presents analysis results obtained primarily from two high-rate global navigation satellite systems (GNSSs) receiver stations designed and operated by the German Aerospace Center (DLR) in cooperation with Bahir Dar University (BDU) at 11.6◦ N, 37.4◦ E
Afterwards, we give a short review of simultaneously observed scintillation events in 2015. This includes the analysis of our scintillation processor output compared to external data from a nearby GNSS station operated by the Technical University of Berlin (TUB)
Summary
It is generally agreed that localized depletions of the lowlatitude F region electron density may be generated due to the Rayleigh–Taylor plasma instability after sunset (Kelley, 2009). Overall GLONASS L2 shows the largest sensitivity with respect to scintillation events These studies confirm the daily and seasonal variability of scintillation events in low-latitude regions reported by Wiens et al (2006) and Alfonsi et al (2013). Afterwards, we give a short review of simultaneously observed scintillation events in 2015 This includes the analysis of our scintillation processor output compared to external data from a nearby GNSS station operated by the Technical University of Berlin (TUB). We estimate the zonal drift velocity and spatial dimension of plasma irregularities over Bahir Dar using a cross-correlation analysis method, which is applied to high-rate data from DLR’s GNSS network
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