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 20 of 29 for “"polar cap"”.
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F-region winds over the central polar cap
F-region neutral winds across the polar cap have been studied by utilizing a Fabry-Perot interferometer located at Eureka (89° CGM), Nunavut Territory, over a 2-winter period 1997/98 and 1998/99. The dependence of neutral winds on the interplanetary magnetic field (IMF) was studied with …
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Modeling of Polar Cap Ionospheric Patches and Attendant Plasma Instabilities: Initialization from Data and Parametric Analysis
… fluid irregularities, particularly within the polar cap region. Within this region though, plasma theory does not always yield tractable problems with succinct analytic solutions that are conceptually illuminating. Observational research methods and techniques, using a multitude of ground-based …
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Investigation of Small Scale (<50m) Surface Features on Mars' North Polar Cap Using Data from HiRISE
The North Polar Layered Deposits (NPLD) of Mars host a wide array of small scale (<50m) features likely to be formed by aeolian processes. Taking data from the High Resolution Imaging Scientific Experiment (HiRISE), features less than 50 m over the entirety of the NPLD are characterized and mapped. …
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The Non-Linear Electrodynamic Coupling Between the Solar Wind, Magnetosphere and Ionosphere
The polar electric potential imposed on the ionosphere by coupling between the earth's magnetosphere and the solar wind has been shown to have a non-linear response to the interplanetary electric field (IEF). This dissertation presents an empirical study of this polar cap potential saturation …
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Ionospheric Convection and Auroral Responses to Solar Wind Driving
… When dayside reconnection is dominant, the polar cap, the area where open magnetic flux meets the Earth's surface, increases. Similarly, when nightside reconnection is dominant, the polar cap decreases in size. This framework is known as the expanding and contracting polar cap paradigm …
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Dynamics of the geomagnetically disturbed ionosphere as measured by GPS receivers and SuperDARN HF radars
… convection electric fields to the formation of a polar cap tongue of ionization (TOI) from mid-latitude plumes of storm enhanced density (SED) during a geomagnetic storm on 26 September 2011. A channel of high density F region plasma was transported from the dayside ionosphere and into the polar …
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Morphology and dynamics of storm-time ionospheric density structures
… we compare observational techniques for tracking polar cap patches during a moderate geomagnetic storm interval. For the first time, we monitor the transportation of patches with high spatial and temporal resolution across the polar cap for 1--2~h using a combination of GPS TEC, all-sky airglow …
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High-Latitude Ionospheric Irregularities Characterized Through Machine Learning Methods
… in the auroral oval and ExB drifts in the polar cap. Using Machine Learning tools, the study aims to distinguish between different scintillation signatures and link them to their sources, improving our ability to detect and characterize these events. Using multiple instruments and advanced …
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Quantitative modeling of time-dependent phenomena in the magnetospheric magnetic field
… which both increase the accuracy and extend the capabilities of the model. A new ring current parameterization improves the determination of storm-time fields in the inner magnetosphere. Replacement of the tail current module with a more flexible representation also contributes to improved …
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Energy deposition in the lower auroral ionosphere through energetic particle precipitation
… absorption in the northern hemisphere polar cap (polar cap absorption –PCA). The occurrence of the absorption events is investigated and a simple empirical relationship between the integral proton flux and the absorption observed during geomagnetically undisturbed PCA conditions is …
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High-latitude electron density observations from the IMAGE radio plasma imager
… Radio Plasma Imager instrument onboard IMAGE is capable of remotely observing electron densities between 0.01 and 100,000 e-/cm-3 from distances of several Earth radii or more. This allows a global view of the high latitude region that has a far greater accuracy than was previously possible. …
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Implications of Martian polar insolation levels on the climatic cycling of volatiles
… presents insolation calculations for Mar's north polar cap for obliquities of 150, 250 and 450. This study found that the elevation of the northern ice cap above the surroundings results in the ice cap having more days of sunlight than previously thought.
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Reverse Convection Potential Saturation in the Polar Ionosphere
… are reported. While it has been shown that the polar cap potential in the ionosphere exhibits non-linear saturation behavior when the IMF becomes increasingly southward, it has yet to be shown whether the high latitude reverse convection cells in response to increasingly northward IMF exhibit …
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Effects of solar particle events on Geospace
… 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 latitude and …
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Comprehensive Model of Jupiter's Polar Aurora
… source of auroral X-ray emission from the Jovian polar caps, whether from electron bremsstrahlung or heavy ion precipitation, has been a topic of debate for the past 40 years, beginning with the Einstein Observatory's first measurement of X-ray emission in 1979. Since then the Roentgen satellite, …
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Kinetic Modeling of Ionospheric Outflows Observed by the VISIONS-1 Sounding Rocket
<p>Plasma escape from the high-latitude ionosphere (ion outflow) serves as a significant source of heavy plasma to magnetospheric plasma sheet and ring current regions. Outflows alter mass density and reconnection rates, hence global responses of the magnetosphere. The VISIONS-1 (VISualizing Ion …
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Statistical study of oxygen+ transport from the cusp to the plasmasheet
… is much larger in the tail lobes than in the polar cap, due to a change in the transport path.</p>
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A Dynamic Coupled Magnetosphere-Ionosphere-Ring Current Model
… but with no significant change in the cross polar cap potential drop, while the region-2 currents shielded the low-latitude convection potential. In addition, oscillations in the magnetic field are produced at geosynchronous orbit with the coupled code. The diagnostics of entropy and mass …
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Surface-atmosphere coupling on Triton and Pluto.
… of the surprising results is that Triton's South Polar Cap is considerably larger than predicted by my model. Another basic result is that the volatile N₂ ice on Triton's surface has a low thermal emissivity (≃ 0.7) relative to canonical emissivity values, which are near unity. Some ambiguity in …
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