An empirical model of ionospheric scintillation at high latitudes (original) (raw)
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Investigating High Latitude Ionospheric Turbulence Using Global Positioning System Data
Statistical properties of the amplitude and phase of GPS L1 signals sampled at 50 Hz are investigated to understand the turbulent behavior of the polar region ionosphere. Wavelet detrended amplitude and phase data are used to construct the probabilitydistribution function (PDF) of the amplitude and phase fluctuations of the signal. Turbulent behaviour of the ionosphere is quantified using the skewness and kurtosis of the PDF. It is found that these two independent moments are related through a parabolic relationship, which was also reported in the case of turbulent neutral fluids and turbulent laboratory plasmas.
Wavelet analysis of GPS amplitude scintillation: A case study
Radio Science, 2007
1] Amplitude scintillations on GPS links due to diffraction by ionospheric irregularities are traditionally described, in their strength, via the standard deviation of the signal power normalized to its average within 1 min, the S 4 index. One should be very careful in using S 4 and always remember that this quantity contains useful information when the signal is stationary for 60 s. In this work, amplitude scintillations are described in a multiscale approach; a wavelet decomposition of the amplitude time series is performed, and the evolution of the signal is studied through its scalogram. What is found is that sudden turbulent events in the amplitude time series, potentially very harmful for the stability and reliability of the radio link, are singled out very clearly in scalograms and cannot be confused with segments of quiet signals. This technique is found to be very useful in those cases in which the signal cannot be considered as stationary over a minute. This new approach is a powerful technique for identifying events that are particularly disruptive to GPS operations. Applications of the new approach in identifying short-duration fading and rapid phase fluctuations are discussed. Citation: Materassi, M., and C. N. Mitchell (2007), Wavelet analysis of GPS amplitude scintillation: A case study, Radio Sci., 42, RS1004,
2014 IEEE/ION Position, Location and Navigation Symposium - PLANS 2014, 2014
The ionospheric scintillation phenomenon that affect the accuracy and integrity of Global Navigation Satellite System (GNSS) is mostly observed in high-latitude and equatorial regions. Scintillation events in these two regions, however, are usually influenced by different factors and thus have different characteristics. This paper makes use of real scintillation data collected at Gakona, Alaska, and Jicamarca, Peru during the current solar maximum to investigate and compare scintillation features observed at the two locations. Based on scintillation events extracted from the raw data, several statistical distributions have been established to characterize the intensity, duration and occurrence frequency of amplitude and phase scintillation. Results confirm that scintillation at low latitudes is generally more intense and longer lasting, while high-latitude scintillation is usually dominated by phase fluctuations and shorter events. The occurrence frequency of scintillation, on the other hand, are influenced by a variety of factors.
Journal of Space Weather and Space Climate
We analyze the amplitude scintillation on L-band signals over San Miguel de Tucumán (Argentina), focusing on the multi-scale variability and speculating on the possible relationship between forcing factors from the geospace and the ionospheric response. The site is nominally located below the expected position of the southern crest of the Equatorial Ionospheric Anomaly (EIA). For this scope, we concentrate on the period 1–31 March 2011, during which one minor and one moderate storm characterize the first half of the month, while generally quiet conditions of the geospace stand for the second half. By leveraging on the Adaptive Local Iterative Filtering (ALIF) signal decomposition technique, we investigate the multi-scale properties of Global Navigation Satellite Systems (GNSS) amplitude scintillation and helio-geophysical parameters, looking for possible cause-effect mechanisms relating the former to the latter. Namely, we identify resonant modes in the Akasofu (ε) parameter as like...
Modeling of ionospheric scintillation
Journal of Space Weather and Space Climate, 2022
A signal, such as from a GNSS satellite or microwave sounding system, propagating in the randomly inhomogeneous ionosphere, experiences chaotic modulations of its amplitude and phase. This effect is known as scintillation. This article reviews basic theoretical concepts and simulation strategies for modeling the scintillation phenomenon. We focused our attention primarily on the methods connected with the random phase screen model. For a weak scattering regime on random ionospheric irregularities, a single-phase screen model enables us to obtain the analytic expression for phase and intensity scintillation indices, as well as the statistical quantities characterizing the strength of scintillation-related fades and distortions. In the case of multiple scattering, the simulation with multiple phase screens becomes a handy tool for obtaining these indices. For both scattering regimes, the statistical properties of the ionospheric random medium play an important role in scintillation modeling and are discussed with an emphasis on related geometric aspects. As an illustration, the phase screen simulation approaches used in the global climatological scintillation model GISM are briefly discussed.
2013
The rate of TEC index (ROTI) is a measurement that characterizes ionospheric irregularities. It can be obtained from standard GNSS dual-frequency phase data collected using a geodetic type of GNSS receiver. By processing GPS data from ground-based networks of International GNSS Service and Continuously Operating Reference Station (CORS), ROTI maps have been produced to observe global and regional scintillation activities. A major mid-latitude scintillation event in the contiguous United States is reported here that was captured in ROTI maps produced using CORS GPS data collected during a space weather storm. The analyses conducted in this work and previously by another group indicate that ROTI is a good occurrence indicator of both amplitude and phase scintillations of GPS L-band signals, even though the magnitudes of ROTI, S4, and sigma(sub phi) can be different. For example, our analysis indicates that prominent ROTI and the L1 phase scintillation (sigma(sub phi)) are well correla...
The earth’s ionosphere is well recognized as a dynamical system and non-linearly coupled with the magnetosphere above and natural atmosphere below. The shape and time variability of the ionosphere indeed shows chaos, pattern formation, random behaviour and self-organization. The present paper studies the propriety of Multifractal Detrended Fluctuation Analysis (MF-DFA) technique for the ionospheric scintillation index time series. MF-DFA is used to identify the scaling behaviour of the ionospheric scintillation time-series data of two different nature. The obtained results show the robustness and the relevancy of the MF-DFA technique for the ionospheric scintillation index time series. The comparison of the MF-DFA results of original data to those of shuffled and surrogate series shows that the multifractal nature of considered time-series is almost due to long-range correlations. Subsequently, the Hurst exponents derived from two parallel methods namely Rescaled range analysis (R/S) and Auto Correlation Function (ACF) are also suggesting the presence of long range correlation. The presented results in this work may be of assistance for future modeling and simulation studies.
GPS and ionospheric scintillations
Space Weather, 2007
1] Ionospheric scintillations are one of the earliest known effects of space weather. Caused by ionization density irregularities, scintillating signals change phase unexpectedly and vary rapidly in amplitude. GPS signals are vulnerable to ionospheric irregularities and scintillate with amplitude variations exceeding 20 dB. GPS is a weak signal system and scintillations can interrupt or degrade GPS receiver operation. For individual signals, interruption is caused by fading of the in-phase and quadrature signals, making the determination of phase by a tracking loop impossible. Degradation occurs when phase scintillations introduce ranging errors or when loss of tracking and failure to acquire signals increases the dilution of precision. GPS scintillations occur most often near the magnetic equator during solar maximum, but they can occur anywhere on Earth during any phase of the solar cycle. In this article we review the subject of GPS and ionospheric scintillations for scientists interested in space weather and engineers interested in the impact of scintillations on GPS receiver design and use.