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

Abstract

Abstract. Small-scale ionospheric disturbances may cause severe radio scintillations of signals transmitted from global navigation satellite systems (GNSSs). Consequently, smallscale 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 setup 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.

Solar Radio Burst Events on 6 September 2017 and Its Impact on GNSS Signal Frequencies

“…STEC represents the total number of electrons along the path in TECU [10 16 electrons/m 2 ]. Here we use relative STEC from 50‐Hz data (for the derivation of STEC; see, e.g., Kriegel et al, ).…”

A Method for Automatic Detection of Plasma Depletions by Using GNSS Measurements

“…This is due to the relative motion of the depletion and the location of the GNSS signal, which is scanning the plasma depletion depending on azimuth ( ) and elevation ( ) angle of the line of sight between the GNSS receiver and satellite. Thus, if a component of the depletion drifts vector (e.g., Kriegel et al, ) is in line with the velocity vector of the ionosphere piercing point, increases. In case, the depletion moves in the opposite direction as the piercing point moves, decreases.…”

“…The equatorial ionosphere with its complex dispersive features is of special interest in space weather research, which supports the operation of space‐based radio systems such as the Global Navigation Satellite System (GNSS) and remote sensing radars. The equatorial ionosphere is commonly characterized by the occurrence of enhanced GNSS signal scintillations in the evening hours (e.g., Hlubek et al, ; Kriegel et al, ). As has already been described many years ago, for example, by DasGupta et al (), the enhancement of amplitude scintillations is inherently associated with total electron content (TEC) depletions.…”

“…Recently, Blanch et al () improved the characterization and modeling of plasma depletion by modifying a previously developed technique for detecting medium‐scale traveling ionospheric disturbances (Hernández‐Pajares et al, ). Based on former scintillation studies by Hlubek et al () and Kriegel et al () at Bahir Dar, we present a new method of describing plasma depletions, which are often associated with GNSS signal scintillations. Here, we focus on describing a new plasma bubble detection algorithm and demonstrating its practical value for automatized bubble detection (and the corresponding statistical analysis).…”

An ionospheric index suitable for estimating the degree of ionospheric perturbations

“…Furthermore, the huge diversity of different structures within the ionosphere like plasma bubbles, patches, gradients Pradipta & Doherty (2016), traveling ionospheric disturbances (TIDs) (Borries et al, 2009) influence high frequency and trans-ionospheric radio wave propagation. So the associated impact causes amplitude and phase scintillation of GNSS signals Basu & Basu (1981), Béniguel et al (2009), Hlubek et al (2014), Kriegel et al (2017) and other ionospheric effects on space-based radar Xu et al (2004).…”