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 23 for “"Polar Vortex"”.
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Understanding Jupiter’s Polar Vortex Crystals
This thesis explores vortex dynamics on background planetary potential vorticity (PV) gradients caused by planetary rotation. Using a quasi-geostrophic (QG) pseudo-spectral model, we investigated the formation of opposing PV annuli that form on the vortex edges as a result of this drift known as a …
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Understanding Jupiter’s Polar Vortex Crystals
This thesis explores vortex dynamics on background planetary potential vorticity (PV) gradients caused by planetary rotation. Using a quasi-geostrophic (QG) pseudo-spectral model, we investigated the formation of opposing PV annuli that form on the vortex edges as a result of this drift known as a …
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Dynamical Influences of Sudden Stratospheric Warmings on Surface Climate
Abstract The stratospheric winter polar vortex consists of strong westerly winds; this winter flow regime can undergo a complete breakdown during sudden stratospheric warming events. In the Northern Hemisphere these events are often accompanied by the descent of anomalous flow regimes which can …
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The role of wavenumber one and two in the development of sudden stratospheric warmings
… effects of planetary waves one and two on the polar stratosphere during boreal winter. We use MERRA reanalysis data and the FMS shallow-water model to compare and contrast their propagation into the stratosphere, their interactions within the stratosphere, and their effects on the polar vortex. …
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The Downward Influence of Ozone Depletion in the Arctic Lower Stratosphere
Severe ozone depletion in the polar lower stratosphere has been linked to significant changes in tropospheric circulation patterns in the both hemispheres. Observed Southern Hemisphere circulation changes are easily reproduced in climate models and may be achieved by either increasing ozone …
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Influence of eddy-eddy interactions and tropical wind variability on sudden stratospheric warming formation
… effects of the oscillations on the stratospheric polar vortex. Model runs with suppressed tropical wind variability are compared to the control run of Chapter 2. A slight increase in SSW frequency can be found in the model runs with suppressed tropical variability. It is found that upper …
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Far-flung influences on midlatitude weather and climate: The stratospheric pathway
… of the Northern Hemisphere stratospheric polar vortex can significantly influence, and enhance the predictability of, midlatitude winter weather on timescales of weeks to months – including the likelihood of weather extremes and associated impacts. This thesis first explores the response …
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Variability of the polar stratospheric vortex and its impact on surface climate patterns
… aspects of the variability of the stratospheric polar vortex and the effect of this variability on tropospheric weather and climate patterns on various timescales. In the first part of this work, an improved idealized model was developed to study the coupled stratosphere-troposphere system. The …
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HF Radar Observations of Inter-Annual variations in Mid-Latitude Mesospheric Winds
… both hemispheres. Coupling between QBO and the polar vortex has been extensively studied over the past few decades, however, less is known about QBO influences in the mid-latitude mesosphere. One reason for this is the relative lack of instrumentation available to study mesospheric dynamics at …
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Post-release establishment and supercooling point assessment of Laricobius osakensis, a predator of the hemlock woolly adelgid
… now been more than 60 releases. In 2014, the polar vortex resulted in significant HWA mortality in the eastern U.S., depleting the food source for L. osakensis, which resulted in low field recoveries of them. In the 2015-2016 field season, there were 14 larvae recovered from the field, and the …
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Studies of wave-mean interaction relevant to the middle atmospheric circulation
… not always negligible. A sharp-edge model on the polar y-plane is introduced in Chapter 5 to study Rossby waves associated with the polar vortex. Results show that the vortex edge can support both free travelling and forced Rossby waves that have a horizontal structure decaying exponentially away …
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Improvements to our Understanding of Toronto-area Atmospheric Composition
… studies were presented in detail.Passage of the polar vortex over the Toronto area was determined by increases in scaled potential vorticity (PV) that coincide with outliers in the HF stratospheric time series. Confirmed with polar PV maps and reductions in N2O stratospheric columns, 53 polar …
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Studies of Stratospheric and Tropospheric Ozone, NO2, and BrO Using UV-Visible Spectroscopy in the Arctic and at Mid-latitudes
… or GBSs) have been taking measurements at the Polar Environment Atmospheric Research Laboratory (PEARL, 80.05°N, 86.42°W) since 1999 and 2006, respectively.The GBS dataset, combined with other measurements at PEARL, was used to validate ozone and NO2 measurements from the Atmospheric Chemistry …
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An Investigation of the Distribution of Ozone-depleting Substances in the Upper Troposphere and Lower Stratosphere
… three mixing barriers investigated, namely the polar vortex, the extratropical tropopause, and the tropical pipe, show that there are inconsistencies between the measurements and the simulations. It was found that the simulation under- predicts mixing efficiency in the tropical lower …
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Ionospheric Disturbances: Midlatitude Pi2 Magnetospheric ULF Pulsations and Medium Scale Traveling Ionospheric Disturbances
… correlated with an index representative of polar vortex activity, possibly controlled by a filtering mechanism that is a function of stratospheric neutral wind direction. Finally, a case study of a radio blackout of transionospheric HF communications caused by an X2.9 class solar flare is …
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Orographic Gravity Wave Drag and the Large Scale Atmospheric Circulation
… the change to the zonal wind profile, where the polar vortex and eddy driven jet are shifted equatorward in the Northern Hemisphere. The sensitivity of the circulation to the strength of the OGWD is then explored. In the Northern Hemisphere, a reduction of the resolved wave drag compensates an …
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Murgantia histrionica (Hahn): new trapping tactics and insights on overwintering survival
… by extreme winters. In 2014 and 2015 the arctic polar vortex extended into mid-latitudes bringing a blanket of sustained sub-freezing temperatures to much of the United States. We used these events to determine effects of extreme winter weather on harlequin bug survival. In both years we observed …
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Bestimmung von Ozonabbauraten über der Arktis und Antarktis mittels Ozonsonden- und Satellitendaten
… arktischen und antarktischen stratosphärischen Polarwirbel. Diese wird durch Abbauprodukte von anthropogen emittierten Fluorchlorkohlenwasserstoffen und Halonen, Chlor- und Bromradikale, verursacht. Studien in denen der gemessene und modellierte Ozonabbau verglichen wird zeigen, dass die Prozeße …
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Trend Analyses of the Abundances of Atmospheric Molecules
… seen in the upper stratosphere of the Antarctic polar vortex.</p> <p>A new version of ACE-FTS routine data product (4.0) provides near global VMR altitude profile of low altitude CO<sub>2 </sub>on a 1 km grid from 5-18 km. An initial evaluation of these data has been carried out for the years …
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Long-term investigation of the lunar tide in the equatorial electrojet during stratospheric sudden warmings
… winters and result in an increase in the polar stratospheric temperature and a reversal of the circumpolar winds. While the phenomenon of SSW is confined to the northern polar stratosphere, its influence on the ionosphere can be observed even at equatorial latitudes. During SSW events, the …
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