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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Atlantic Multidecadal Oscillation-Forced Regional Summertime Precipitation Variations In The Central United States, Michael C. Veres
Atlantic Multidecadal Oscillation-Forced Regional Summertime Precipitation Variations In The Central United States, Michael C. Veres
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
The purpose of this research is to identify the regional mechanisms by which the Atlantic Multidecadal Oscillation (AMO) influences summer (June-August) precipitation in the central U.S. This was accomplished by running two different sets of simulations using the Weather Research and Forecasting (WRF) regional climate model, one forced by observations and the other forced only by variations in the AMO as obtained via a global climate model (GCM). The results reveal a complex set of mechanisms active in the lower and middle troposphere by which the AMO influences summer circulation and precipitation in the central U.S. During the cold phase …
The Application Of Biostratigraphy And Paleoecology At Southern Ocean Drill Sites To Resolve Early To Middle Miocene Paleoclimatic Events, Ryan Farmer
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
The diatom biostratigraphy and paleoceanography of Ocean Drilling Program (ODP) Site 744 on the Southern Kerguelen Plateau, southern Indian Ocean are documented for the early to middle Miocene to improve chronostratigraphic age control for the Southern Ocean and Antarctic region. Paleoenvironmental fluctuations in the Southern Ocean are inferred from changes in fossil diatom abundance, preservation, and assemblage composition. A robust, new age model for Holes 744A and 744B is constructed using Constrained Optimization (CONOP) model ages for diatom biostratigraphic datum levels and new magnetic polarity data, which enables assessment of a nearly continuous record of paleoenvironmental change from ~20.25 to …
Using Electrical Resistivity Imaging To Map Saline Groundwater And Subaqueous Spring Discharge: An Example From The Saline Wetlands Of Eastern Nebraska, Bridget B. Kelly
Using Electrical Resistivity Imaging To Map Saline Groundwater And Subaqueous Spring Discharge: An Example From The Saline Wetlands Of Eastern Nebraska, Bridget B. Kelly
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
In order to better understand saline groundwater distribution and discharge dynamics within the saline wetlands of eastern Nebraska, electrical resistivity data were collected at three wetland sites within the Little Salt Creek Watershed. Electrical resistivity imaging (ERI) can provide an expanded understanding of saline groundwater distribution through the acquisition of a large number of resistivity measurements collected at the surface; upon inversion, the distribution of resistivity can be displayed in cross-section and subsurface processes serving to control salinity can be inferred. In recent years, several studies have used conventional methods of characterizing groundwater flow within the saline wetlands. These point …
Stratigraphic Analysis And Regional Correlation Of Isolated, Top-Truncated Shallow Marine Sandstone Bodies Within The Upper Cretaceous Frontier Formation, Bighorn And Washakie Counties, Wyoming, Andrew J. Hutsky
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
A detailed sedimentologic and stratigraphic analysis facilitated interpretations of depositional environment, sequence stratigraphy, and sandstone body geometry for isolated, top-truncated, shallow marine sandstone bodies of the Upper Cretaceous (Cenomanian-Turonian) Frontier Formation, northeast Bighorn Basin, Wyoming. The Frontier Formation interval is ~160 meters thick and was deposited as a complex clastic wedge that prograded into Cretaceous Western Interior Seaway (KWIS). The vertical interval comprises several incomplete coarsening-upward cycles, composed of basal offshore marine and prodeltaic shales progressively overlain by proximal shallow marine/fluvial facies that are capped by pebble lags. Sedimentary structures, vertical stacking patterns, and lateral variability within these cycles record …
New Stable Isotope Record Of Paleoecological Change In The Late Neogene Of The Western Great Plains From Enamel In Large Mammals, Zachary Kita
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
An expansion of C4 grasslands occurred between 6 and 8 million years ago in the Great Plains of North America, as evidenced by a marked shift to more 13C-enriched carbon isotope compositions from large fossil mammal tooth enamel and paleosol carbonates. Prior to this expansion, habitats were comprised of exclusively C3 vegetation. To explore this problem I present a compilation of bulk stable carbon (δ13C) and oxygen (δ18O) isotope values from a variety of large mammals from 6 localities that span from the late Clarendonian to the late Blancan in Nebraska. As expected, …
Sedimentology And Stratigraphy Of The Upper Pennsylvanian – Lower Permian Systems Of Western Nebraska, Usa, Chesney L. Gilleland
Sedimentology And Stratigraphy Of The Upper Pennsylvanian – Lower Permian Systems Of Western Nebraska, Usa, Chesney L. Gilleland
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Depositional patterns and regional stratigraphic relationships in the carbonate-dominated Pennsylvanian and Permian deposits in western Nebraska are not well established due to poor surface exposure. Examination of petroleum drillcores and wireline logs, along with thin sections and biostratigraphic analysis allow new insight into facies distributions, depositional environment, and regional stratigraphic relationships. Nine shallowing upward cycles are identified that can be correlated across the southern Nebraska Panhandle within the Pennsylvanian (Virgilian)-Permian (Wolfcampian) stratigraphy (Admire, Council Grove, and Chase Groups). These cycles are composed of facies representing deposition from open marine through nonmarine environments. Results show that depositional settings in western Nebraska …
Verification Of The Cobb Snowfall Forecasting Algorithm, Josh Barnwell
Verification Of The Cobb Snowfall Forecasting Algorithm, Josh Barnwell
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Forecasting storm total snow accumulation is one of the most difficult aspects of meteorological forecasting. The forecaster has to interpret three main variables in order to forecast snowfall accurately. These forecasting variables are the duration of the snowfall, the amount of liquid water the storm will produce, and the snow density or snow ratio. With the advancement of computer models in recent history, the need for a quick and easy interpretation of these variables has grown, and to improve on previous forecasting techniques’ disadvantages with including the three snow forecasting variables. The Cobb Method snowfall forecasting algorithm utilizes model data …
Trends Of Wind And Wind Power Over The Coterminous United States, Eric M. Holt
Trends Of Wind And Wind Power Over The Coterminous United States, Eric M. Holt
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
The trends of wind and wind power at a typical wind turbine hub height (80 m) are analyzed using the North American Regional Reanalysis (NARR) dataset for 1979-2009. Based upon the wind speeds at NARR’s vertical layers right above and below the 80 m level, the wind speeds at 80 m are estimated using two methods assuming the wind profile respectively as linear and power-law distribution with respect to the altitude in the lower boundary layer. Furthermore, we calculate the following variables at 80 m that are needed for the estimation and interpretation of wind power: the air density, zonal …
Improved Verification And Analysis Of National Weather Service Point Forecast Matrices, Paul Fajman
Improved Verification And Analysis Of National Weather Service Point Forecast Matrices, Paul Fajman
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Verification is the process of determining the quality of forecast information. Office and personal forecast verifications are significantly lacking throughout the National Weather Service for many reasons. The primary reasons are that verification is time consuming, tedious, and monotonous. This research attempted to ease that process by creating new computer procedures to automate the verification process. The new procedures were tested using two years of forecasting data from November 2007 to November 2009 from the Omaha/Valley Weather Forecasting Office to serve as a framework for future verifications. Point Forecast Matrices (PFM) produced by the National Weather Service twice daily and …