Physical Sciences and Mathematics Commons^™

Late Paleozoic Climatic Reconstruction Of Western Argentina: Glacial Extent And Deglaciation Of Southwestern Gondwana, Kathryn N. Pauls

Theses and Dissertations

Throughout its history Earth has experienced both icehouse and greenhouse conditions. Shifts and transitions from one end member to the other are driven by numerous driving mechanisms on global, orbital and more local scales. In particular, the late Paleozoic ice age (LPIA) is thought to have been driven by global drivers such as the drift of the Gondwanan continent across the South Pole, fluctuations in atmospheric CO2 concentrations, and Milankovitch cycles. It was also affected by more local and regional drivers such as active tectonism along accretionary margins and changes in atmospheric and oceanic circulation patterns. South American Gondwana provides …

Biennial And Low-Frequency Components Of El Niño/Southern Oscillation, James Michael Ryan

Theses and Dissertations

El Niño/Southern Oscillation (ENSO) is a coupled oscillation of sea surface temperatures (SSTs), winds, and air pressure in the eastern and central tropical Pacific, that repeats with quasi-regularity, every 2–7 years. Although the ENSO’s spectral peak is found at a 4–7-yr period, composite El Niño events, taken as the 84 months before and after the peak of each El Niño, show that the length of each event, and often the following La Niña if there is one, usually falls within a quasi-biennial (QB) range of around 18–42 months. We argue that the biennial range of ENSO events stems from the …

Predicting Peak Wind Gusts During Specific Weather Types With The Meteorologically Stratified Gust Factor Model, Teresa Jean Turner

Theses and Dissertations

Peak wind gusts were estimated by the meteorologically stratified gust factor model at Milwaukee, WI (KMKE) for eight different weather types during 2010-2017. The gust factor model couples gust factors with wind speed and direction forecast guidance to produce peak gust forecasts. The model evaluated used two model output statistics (MOS) guidance products at lags ranging from 6-24 hr and was compared with peak gust forecasts provided by the Localized Aviation MOS Program (LAMP) as well as observed gusts reported by automated surface observing systems (ASOS).

Compared with climatology, the gust factor model showed skill when coupled with MOS in …

An Investigation Into The Trophic Magnification Of Polychlorinated Biphenyls In The Lake Michigan Food Web, Philip Hurst

Theses and Dissertations

Polychlorinated biphenyls (PCBs) are a group of persistent organic pollutants known to contribute to several adverse health conditions in humans including cancers and a suite of liver diseases. While there exist 209 unique PCB congeners, the World Health Organization has identified 12 that pose the greatest health risk to humans due to these congeners’ functional similarity to dioxins, another notoriously toxic class of contaminants. Along with methylmercury, PCBs are the primary drivers behind fish consumption advisories in the Great Lakes. These guidelines are informed primarily by surveys of contaminants in freshwater biota. However, the proliferation of invasive species, such as …

A Feasibility Study Of Microbialites As Paleomagnetic Recorders, Ji-In Jung

Theses and Dissertations

Microbialites are carbonate organosedimentary deposits formed by benthic microbial communities that trap and bind detrital sediments, and/or inorganic and biologically influenced calcification. Any ferromagnetic particles incorporated into the microbialite structure have the potential to preserve variations in Earth’s magnetic field. A paleomagnetic record in microbialites would be useful for reconstructing the geomagnetic field because it may record at a high temporal resolution based on estimated growth rates, thus preserving relatively short-period variations of the Earth’s magnetic field. In addition, microbialites can be found in the geologic record going back ~3.5 Ga, hence potentially providing information on very ancient variations in …

Multidecadal Climate Variability In Observed And Simulated Surface Air Temperature And Sea-Level Pressure, Andrew Aden Westgate

Theses and Dissertations

Accurate estimates of multidecadal climate variability generated internally within the climate system are required to gauge anthropogenic contribution to warming trends and to develop efficient strategies to mitigate climate change. Previous analyses of historical surface air temperatures (SAT) showed that numerical climate prediction models lack a pronounced global mode of observed internal variability — the stadium wave (SW), — which represents a multidecadal undulation originating in the North Atlantic and propagating to other regions of the globe. The present study extends these analyses by exploring co-variability of SAT and sea-level pressure (SLP) within the SW. Addition of SLP data does …

Modeling Of Cloud Droplet Formation: Software Development And Sampling Strategies, Niklas Selke

Theses and Dissertations

Updraft speeds are an important factor in the formation of cloud droplets which play an important role in an atmospheric simulation. The updraft speeds are varying very strongly in small areas of space. Current models do not account for this kind of variability. Support for a probability density function (PDF) based approach in representing the variability of the updraft speeds has been implemented in the Energy Exascale Earth System Model (E3SM). Specifics of the implementation process have been discussed.

Different sampling strategies were tested to analyze the convergence behavior of the new approach to the cloud droplet formation process. It …