Fig 15 - uploaded by Sandro Radicella
Content may be subject to copyright.
Source publication
Radio wave scintillations are rapid fluctuations in both amplitude and phase of signals propagating through the atmosphere. GPS signals can be affected by these disturbances which can lead to a complete loss of lock when the electron density strongly fluctuates around the background ionization level at small spatial scales. This paper will present...
Similar publications
The ionospheric scintillation responses to tropical cyclones passing through the ocean near Australia, named as MARCUS in 2018, DEBBIE in 2017, MARCIA in 2015, and YASI in 2011, are investigated using GPS amplitude scintillation S4 index data collected from GPS stations of Ionospheric Scintillation Monitors installed in Darwin, Weipa, and Willis Is...
This study characterizes low-latitude scintillations at L-band frequency
in South America on daily, monthly, and seasonal time scales at three
levels of solar activity: high, moderate and low levels. Three years
(November 2001-October 2002, 2004 and 2008) of amplitude
scintillation data from GPS receivers at three locations: Cuzco
(14.0°S, 73.0°W,...
The FORMOSAT-3/COSMIC (F3/C) satellite probes the S4 scintillation index profile of GPS signals by using the radio occultation (RO) technique. In this study, for practical use on the Earth’s surface, a method is developed to convert and integrate the probed RO S4 index, so obtaining the scintillation on the ground. To estimate the worst case, the m...
Irregularities in electron density usually correlate with ionospheric plasma perturbations. These variations causing radio signal fluctuations, in response, generate ionospheric scintillations that frequently occur in low-latitude regions. In this research, the combination of an artificial neural network (ANN) with the genetic algorithm (GA) was im...
This paper presents a review of the ionosphere scintillation characteristics recorded at low and high latitudes. The European Space Agency (ESA) MONITOR database has been used to support the analysis. We review in particular the different indices and the values recorded by the different kinds of receivers deployed during the measurement campaign. T...
Citations
... Due to the lack of real measurements of the scintillation intensity in the downlink frequency of the Cuiabá station (2 208 MHz), the GISM model (Global Ionospheric Scintillation Model) [27] was used to make estimates of parameter 4 , which is normally used to define the scintillation intensity in terms of amplitude. Different orbits for the satellite of interest and several different conditions of solar flux were considered in this estimate. ...
... Using single receivers is useful when one have rarefied network, and it minimizes the obtaining and data processing efforts. Classical index for studying ionospheric irregularities is scintillation index S4, that is regularly measured by GNSS receivers (Béniguel et al., 2004). The S4 index is usually associated with small-scale irregularities, comparable with the Fresnel radius, and leading to phase and amplitude distortions of the received signal. ...
Various ionospheric indices based on Global Navigation Satellite Systems data are widely used to study ionospheric disturbances. Two of them, produced from the Slant Total Electron Content measurements are studied in the paper: well known AATR index and relatively new WTEC index. A comparative statistical analysis of AATR and WTEC indices was made using ISTP SB RAS receivers network. We compared AATR and WTEC indices for studying small- and mid-scale ionospheric disturbances in different geophysical conditions and different geographical regions. The analysis was carried out at high, equatorial and middle latitudes during 2014–2017. It is shown that the contribution of diurnal variations of the background ionosphere to AATR is higher than to WTEC. It is shown that at high latitudes the WTEC and AATR dynamics correlates with the level of geomagnetic disturbance (Kp index). At mid-latitudes, the contribution of Vertical Total Electron Content prevails other effects. Preliminary statistical analysis of 25 earthquakes with magnitude ¿6.8 shown that effect of internal atmospheric waves prevails the effect of shock acoustic waves from ground vibrations. The analysis demonstrated that at low disturbance levels (WTEC < 0.1TECU) WTEC index looks more sensitive than AATR; at high disturbance levels, the WTEC is nearly proportional to AATR with a factor of 1.5min−1.
... Classical index for studying ionospheric irregularities is scintillation index S4, that is regularly measured by GNSS receivers (Béniguel et al., 2004). The S4 ...
A comparative statistical analysis of AATR and WTEC indices was conducted based on data from the ISTP SB RAS GNSS receivers network. It is shown that at high levels of ionospheric disturbance (for WTEC > 0.1 TECU), the AATR index is proportional to the WTEC index with a factor of $1.5min^{-1}$. At small levels of ionospheric disturbance (for WTEC < 0.1 TECU), this proportionality is violated. It is shown that the contribution of daily dynamics of the background ionosphere to the AATR index is higher than to the WTEC index. This leads to a higher sensitivity of the WTEC index to disturbances. This also leads to violating the proportionality between WTEC and AATR indices at low levels of ionospheric disturbance. It is shown that at high latitudes the dynamics of the WTEC and AATR indices correlate significantly with the level of geomagnetic disturbance Kp. At mid-latitudes, the contribution of solar radiation variations (F10.7 index) and vertical seismic variations exceeds the influence of Kp variations. The program for calculating WTEC indices, used in the paper is put into open access.
... There are a few well established global scintillation models. For example, global ionospheric scintillation model (GISM) by Béniguel [10], which uses the multiple phase screen method [10][11][12][13]. Another established model was WideBand MODel (WBMOD) ionospheric scintillation model by Secan et al. [14]. ...
... If we choose the same cut-off frequency that we use for the low latitude this will artificially enhance the scintillation indices, and this enhancement is more visible in phase scintillation index due to phase fluctuation's direct dependence on the spectral index at the low temporal frequencies; than amplitude scintillation index (Forte and Radicella 2002). When the detrending cutoff frequency is 0.1 Hz this signal gets contaminated due to the refractive phase shits at the high latitudes and as a consequence, TEC gradients directly influence the phase scintillation index (Forte 2005;Forte and Radicella 2002;Béniguel et al. 2004;Beach 2006). Considering the problems related to the lower cutoff frequency of 0.1 Hz, in the presented paper scintillation indices are calculated from the raw L1 signal carrier phase and intensity data. ...
A geomagnetic storm occurred on 27 February 2014 and the shock related to it arrived at Earth’s magnetosphere at ∼17:00 UT. Dayside cusp region scintillation over Antarctica have been studied along with the Global Positioning System (GPS) observed total electron content (TEC), and Defense Meteorological Satellite Program (DMSP) Precipitating Particles (SSJ), Bulk Plasma Parameters (SSIES) and Magnetic Fields (SSM) data. For the first time, similar variation trend in amplitude and phase scintillation has been found near the polar latitude. Amplitude scintillation index (S4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\mbox{S}_{4}$\end{document}) and phase scintillation index (σφ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\sigma _{\varphi }$\end{document}) show the similar enhancement trend at different numerical scale. During the southward interplanetary magnetic field (IMF) Bz condition there is a significant enhancement in the particle precipitation occurred through the dayside cusp region. During southward IMF Bz and dawnward By (By<0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\mbox{By} < 0$\end{document}), high convection velocity guide solar wind plasma into the polar cap which enhances the phase scintillation, but, no amplitude scintillation enhancement at the similar numerical scale. The Halley and Dome C East radar data show that at the small to medium ionospheric irregularity speed, S4, and σφ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\sigma _{\varphi }$\end{document} variations are alike. If proper variation scale is chosen, S4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\mbox{S}_{4}$\end{document} also appears an appropriate scintillation index for the polar ionosphere. The possible mechanism for S4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\mbox{S}_{4}$\end{document} occurrence similar to the σφ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\sigma _{\varphi }$\end{document} at a dissimilar level has been discussed.
Key points: Dayside cusp region amplitude and phase scintillation indices give similar information but at different numerical scale during the geomagnetic storm onset.
Amplitude scintillation index is also an appropriate scintillation index for high latitude if proper numerical scales are chosen.
SED or TOI does not necessarily produce ionospheric scintillation.
Southward IMF Bz and westward IMF By allows the scintillation producing ionospheric irregularities to pass in deep inside the South Pole.
... A plausible scenario where individual satellite disturbances can pose a challenge to carrier phase vector tracking algorithms is when ionospheric scintillation occurs. Scintillation has been studied for decades in the propagation theory, and its impact on GNSS signals is described in a vast number of articles (for example [11], [12], [13]) . The importance of this study is especially critical when the solar activity reaches peak values, which happens with a periodicity of eleven years. ...
... There are a few well established global scintillation models. For example, global ionospheric scintillation model (GISM) by Béniguel [10], which uses the multiple phase screen method [10][11][12][13]. Another established model was WideBand MODel (WBMOD) ionospheric scintillation model by Secan et al. [14]. ...
Mid-latitude ionospheric scintillation has been studied in very poor proportion as compared to the equatorial and high latitude ionospheric scintillation. Mid-latitude ionospheric scintillations are often associated with either day time photo-ionization or due to the storm enhanced density. Using the phase screen model and the wave propagation theory in random media, we have identified the orientation of the ionospheric irregularities over Weihai with the local geomagnetic field. Amplitude and phase scintillation data observed using GPS scintillation receiver deployed at the mid-latitude observation station Weihai, have been used along with K-index derived from the horizontal magnetic field component of the local magnetometer. The proposed model uses the scintillation indices relationship with the local K-index. We identified the scintillation dependence over local K-index during geomagnetic quiet and disturbed condition. This dependence coefficient is used on the real scintillation data for modeling. The presented scintillation model has been validated by comparing it to the real observations. The co-relation coefficient is more than 90% during the disturbed as well as quiet geomagnetic conditions.
... Ionospheric irregularities are responsible for generating scintillation in electromagnetic signals passing through them. When the electromagnetic signal propagates through the irregular ionosphere, it gets distorted in terms of phase and amplitude, a phenomenon which is known as phase and amplitude scintillation respectively [Aarons et al. 1980, Béniguel et al. 2004]. Severe scintillations can cause problems such as signal power fading, phase cycle slips, and receiver loss of lock and can thus degrade the quality of satellite-based communication and navigation systems. ...
Ionospheric irregularities degrade the performance of radio technological system by producing fluctuations in amplitude and phase of signal passing through them, a phenomenon which is known as scintillation. This study presents diurnal and seasonal variations of ionospheric irregularities during ascending phase of solar activity from 2009 to 2014 by using the amplitude scintillation index S4 computed from a dual frequency GPS receiver installed at the low-latitude station of Varanasi (Lat. 25.31° N, Long. 82.97° E). Scintillation occurrences are found to be higher during nighttime hours (1930-0130 LT), and characterized by an equinoctial maximum throughout the years 2009-2014, except for the peculiar solar minimum year 2009. Gravity wave seed perturbation from lower atmosphere and pre-reversal enhancement (PRE) in zonal electric field have been considered to explain the observed seasonal occurrences, which have been also compared with previous results obtained from observations and model. Influence of solar activity on scintillation occurrence has also been studied, and it was found that there is linear dependence between the solar activity and scintillation occurrence, which is seasonally variable.
... This ionospheric activity concentrates predominantly in the polar and equatorial regions (±20 • of geomagnetic Equator). The nuisance is particularly harmful in global navigation satellite system (GNSS) transmissions as deep signal fading degrades or disrupts the processor operation [1], [2]. ...
... where ξ is the normalized frequency. The relation between the correlation coefficients and the AR(q) coefficients is expressed by the Yule-Walker equa- tion [26], r y = R , with r y = [r y (1) r y (2) . . . r y (q)] T , = [θ 1 θ 2 . . . ...
The generalized gamma distribution includes as particular cases different well-known distributions, such as the Nakagami-m. We propose a computationally efficient technique to generate correlated time-series with generalized gamma distribution. This method is useful in the simulation of GNSS signals disturbed by ionospheric scintillation. The technique requires only knowledge of two parameters, besides the definition of a model for the amplitude power spectrum.
... All this invokes to seriously study the ionosphere impact on the GNSS signal propagation in the highlatitude region 2,5,13 . For example, noted is a high level of phase scintillations at high geomagnetic latitudes during magnetic storms 6 and during the maximal solar activity 12 . Astafyeva et al. (2014) 4 showed the region of most slips in determining the total electron content (TEC) is located near the auroral oval. ...
