Global ETD Search
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Showing 1 to 18 of 18 for “"Ionospheric Irregularities"”.
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High-Latitude Ionospheric Irregularities Characterized Through Machine Learning Methods
… and data-driven techniques to understand plasma irregularities in high-latitude regions better. By combining observations and recent findings from modeling, the goal is to identify and classify scintillation signatures caused by different types of irregularities in the ionosphere. The focus is on …
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Investigation of High Latitude Ionospheric Irregularities utilizing Modeling and GPS Observations
… coupling mechanisms result in high latitude irregularities that are difficult to characterize. Until recently, the polar and auroral irregularities remained largely unexplored. Inadequate infrastructures to deploy and maintain advanced dual frequency Global Navigation Satellite System (GNSS) …
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The Mid-Latitude Ionosphere: Modeling and Analysis of Plasma Wave Irregularities and the Potential Impact on GPS Signals
… Recent studies reveal that the mid-latitude ionospheric irregularities are less understood due to lack of models and observations that can explain the characteristics of the observed wave structures. Since temperature and density gradients are a persistent feature in the mid-latitude …
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Numerical analysis and visualization of the ionospheric Kelvin-Helmholtz instability
… the numerical modeling of processes that produce ionospheric irregularities; namely the evolution of the Kelvin-Helmholtz instability (KHI) is studied. The simulation model consists of two-dimensional, electrostatic, nonlinear, and time dependent fluid equations that describe the KHI evolution. …
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Three-Dimensional Fluid Simulations of Mid-Latitude Ionospheric Processes with Hybrid Chebyshev/Fourier Pseudo-Spectral Methods
Ionospheric irregularities are small-scale plasma density structures driven by instabilities arising from combinations of plasma drifts, density gradients, and electric fields. These irregularities can cause mid-latitude GPS scintillations, characterized by amplitude and phase fluctuations that …
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A Multidimensional Characterization of MUIR Backscatter Spectra Resulting from Ionospheric Heating Experiments Performed at HAARP
… characterization of the various artificial ionospheric heating features by varying HF aspect angle, HF pump frequency, UHF pointing angle, and heating pulse time. Through the use of the HAARP HF array and the MUIR UHF radar, we observed cascade (LDI), collapse (cavitons), parametric decay …
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An examination of ionospheric plasma irregularities detected by the mid-latitude SuperDARN radars
… developed a method for identifying periods of ionospheric backscatter that increase the number of data and reduce the average velocity in agreement with previous incoherent scatter radar (ISR) studies. Analysis of the data identified by this method clearly shows that different types of …
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Remote Sensing of Irregularities in the Equatorial Ionosphere Using the Radio Scintillation Technique
… to remotely sense the characteristics of the ionospheric irregularities. This is done by considering both statistical and deterministic models for the scintillation producing irregularities. The models are combined with existing propagation theory using analytical and numerical simulation …
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Dynamics of the geomagnetically disturbed ionosphere as measured by GPS receivers and SuperDARN HF radars
… GPS receivers is compared to HF backscatter from ionospheric irregularities obtained by Super Dual Auroral Radar Network (SuperDARN) radars. We present the first observations of a recurrent region of anomalous enhanced TEC at mid-latitudes over North America and attempt to characterize its …
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GNSS-based Spacecraft Formation Flying Simulation and Ionospheric Remote Sensing Applications
… navigation for spacecraft formation flying. Ionospheric remote sensing, such as Total Electron Content (TEC) measurements or ionospheric irregularity studies are important potential Low Earth Orbit (LEO) applications. A GNSS-based Hardware-in-the-loop (HIL) simulation testbed for LEO …
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2-D radio imaging of equatorial ionospheric plasma depletions with the C/NOFS satellite: algorithms and results
Local depletions in the equatorial ionospheric electron density, known as spread-F events, have been an active area of scientific research in the last decades. These are of special interest to the research community because of their potentially deleterious impact on trans-ionospheric communication …
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Contemporary Ionospheric Scintillation Studies: Statistics, 2D Analytical and 3D Numerical Inversion
The propagation of radiowaves through ionospheric irregularities can lead to random amplitude and phase fluctuations of the signal, otherwise known as scintillation, which can severely impact the performance of Global Navigation Satellite System (GNSS) and communication systems. Research into high …
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Radio Propagation Through Density Irregularities in the Auroral Ionosphere
… fluctuations. These fluctuations are called<em> ionospheric</em><em> scintillation</em>. Scintillation effects can be detrimental to Global Navigation Satellite Systems (GNSS) such as Global Positioning System (GPS), but the observed effects can be used as a tool to study the underlying plasma …
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Ionospheric imaging with compressed sensing
… how ideas from compressed sensing can benefit ionospheric imaging in two ways. Compressed sensing suggests signal reconstruction techniques that take advantage of sparsity, offering us new ways of interpreting data, especially for undersampled problems. One example is radar imaging. We explain …
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Modeling of Plasma Irregularities Associated with Artificially Created Dusty Plasmas in the Near-Earth Space Environment
… for enhanced radar scatter from plasma irregularities embedded in dusty plasmas in space. Plasma irregularities embedded in a artificial dusty plasma in space may shed light on understanding the mechanism for enhanced radar scatter in Noctilucent Clouds (NLCs) and Polar Mesospheric …
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Ultra-Low Frequency Waves at Middle Latitudes During Substorms: Observations and Modeling
… background of the Field-Line Resonance and Ionospheric Feedback Instability as well as the methodology for the 2D RMHD two-fluid simulations at mid latitudes. The results from the numerical study presented in the dissertation demonstrate that the plasmapause plays a very important role in …
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Study of waves observed in the equatorial ionospheric valley region using Jicamarca ISR and VIPIR ionosonde
… and ionosonde (VIPIR, vertical incidence pulsed ionospheric radar) data were taken concurrently at Jicamarca during campaigns of January, April, June, and July 2015, January 2016, and most recently April 2017 to bring more insight into the state and dynamics of the ionospheric E-F valley region …