Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 18 of 18 for “"substorm"”.
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Statistical Study of Solar Wind Conditions Prior to Substorm Onsets
… multi-region, coupled plasma systems, auroral substorm onsets have been historically difficult to predict. The northward turning of the interplanetary magnetic field was considered the primary candidate as an external triggering mechanism for substorm onsets. However, that was later shown to be …
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Calculation of magnetic effects due to a model substorm current system
… ground magnetic perturbations due to a substorm current system in the magnetosphere. The relevant currents are determined using results of a numerical simulation of the substorm itself devised by R. A. Wolf and collaborators. The magnetic fields due to the currents are calculated …
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Solar Wind-Magnetosphere Coupling: A Global Perspective of Reconnection in the Magnetotail
… present a case study of the 25 December 2015 substorm which occurred between 08:15 and 08:45 Universal Time. During this interval, fast particle flows and field geometry consistent with magnetic reconnection were detected in the mid-tail region. An ejected plasmoid was observed by the …
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MODELING OF PLASMA-SHEET CONVECTION: IMPLICATIONS FOR SUBSTORMS (MAGNETOSPHERE)
… to be released in sporadic events, namely substorms. It is shown that the idea of steady convection is inconsistent with the idea of slow, approximately lossless, plasma convection in a long, closed-field-line region that extends into a long magnetotail, such as occurs during Earthward …
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Large-scale observations of the spatial and temporal dynamics of quiet-time Sub-auroral Polarization Streams using SuperDARN HF Radars
… embedded within SAPS channels, especially during substorm recovery phases. Quiet-time SAPS studies, although relatively few, have shown these SAPS to be associated with much weaker velocities and to be influenced by substorm intensifications. However, these studies have been limited in their …
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Global Structure of the Nightside Proton Precipitation during Substorms using Simulations and Observations
… for the nightside proton precipitation. During substorms, the outflow from the near earth reconnection line at approximately 20 RE brings magnetic flux from the highly stretched magnetotail into the near earth magnetosphere. Once there, the flux piles up forming an azimuthally localized region …
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Kinetic Modeling of Ionospheric Outflows Observed by the VISIONS-1 Sounding Rocket
… Ion Outflow via Neutral atom imaging during a Substorm) sounding rocket was launched on Feb. 7, 2013 at 8:21 UTC from Poker Flat, Alaska, into an auroral substorm with the objective of identifying the drivers and dynamics of nightside ion outflow at altitudes where it is initiated, below 1000 …
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The Study of Magnetotail Dynamics and their Ionospheric Signatures using Magnetohydrodynamic Simulation Model: OpenGGCM
… represent the onset of the tail reconnection and substorms in the ionosphere. To investigate signal propagation paths and signal travel times, single impulse or sinusoidal pulsations are launched at different locations of the plasmasheet, and the paths taken by the waves and the time that …
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Space- and ground-based observations of pulsating aurora
… believed to occur mainly in the aftermath of a substorm, resulting in widespread auroral luminosity corresponding to a significant transfer of power from the magnetosphere to the ionosphere. A handful of theories have been proposed to explain the associated precipitation mechanism, which have …
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A statistical study of plasmawaves and energetic particles in the outer magnetosphere
… of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft, Cluster mission, the Geostationary Operational Environment Satellites (GOES), Los Alamos National Laboratory (LANL) satellites, the Polar spacecraft and the Active Magnetospheric Particle Tracer Explorers …
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Ionospheric Convection and Auroral Responses to Solar Wind Driving
… of solar wind driving and the auroral response. Substorms are a sporadic magnetospheric response mode, where the polar cap expands at first, followed by a distinct nightside brightening of the aurora and a decrease in polar cap flux. Steady magnetospheric convection events (SMCs) are times when …
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Data Driven Prediction Without a Model
… which exhibit low dimensional behavior on the substorm time scale. The time series data of the magnetic field variations monitored by the network of ground-based magnetometers in the auroral region are used for forecasting at two stages. In the first stage, the auroral electrojet indices, …
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Sounding rocket measurements of thermal electrons in active nightside aurora
… Poker Flat Research Range, Alaska into active substorm expansion aurora and reached 735 km. For the first time, direct measurements of the cold ionospheric population in darkness were made by the UNH Thermal Electron Detector (TED). At these middle altitudes, understanding this population is …
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Effects of ionospheric oxygen on magnetospheric structure and dynamics
… Finally, I show that during a realistic substorm simulation, the timing and strength of substorms are changed by a global O + outflow.
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Driving Influences of Ionospheric Electrodynamics at Mid- and High-Latitudes
… 5, we examined the external drivers of magnetic substorms using machine learning. We presented the first deep learning based approach to directly predict the onset of a magnetic substorm. The model has been trained and tested on a comprehensive list of onsets compiled between 1997 and 2017 and …
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Ultra-Low Frequency Waves at Middle Latitudes During Substorms: Observations and Modeling
… Frequency (ULF) waves at middle latitudes during substorms. The dissertation consists of two major parts, observations and simulations. The research in this dissertation proposes that the main role in the generation of ULF waves at middle latitudes during substorm belongs to the plasmapause.</p> …
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Investigation of High Latitude Ionospheric Irregularities utilizing Modeling and GPS Observations
… We also implement SIGMA for analyzing a substorm event observed by AAL-PIP stations. One of the unique contributions of this research is to demonstrate that such an inverse modeling technique can form a basis in the investigation of the ionospheric irregularities. Moreover, availability …
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Effects of solar particle events on Geospace
… geomagnetic storms, cutoff latitude depression, substorms and polar cap absorption. The energetic proton populations of three selected SEP events from 2001 are used as 'tracers' to quantify the compression of the geomagnetic cavity during storm conditions. Empirical relations between the cutoff …