Physical Sciences and Mathematics Commons^™

The Impact Of Reduced Arctic Sea Ice Extent On Cryospheric Snowfall, Alexander Carne

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Satellite observations show that sea ice extent in the Arctic has been declining from 1979 through present day, reaching record minimum extents in 2007 and 2012. Reduced sea ice extent allows for greater expanses of open water to interact with the Arctic atmosphere, potentially leading to changes in the Arctic climate. The greatest declines in Arctic sea ice extent have occurred in summer and autumn. During these seasons, it is likely that the decrease in Arctic sea ice extent led to an increase in atmospheric sensible and latent heat fluxes, possibly leading to increases in Arctic temperature and moisture. Increases …

Early Miocene Quantitative Calcareous Nannofossil Biostratigraphy From The Tropical Atlantic, Waheed A. Albasrawi

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Quantitative analysis for the Lower Miocene of Ocean Drilling Program Hole 959A from the West African margin was performed to document all the calcareous nannofossil biostratigraphic events present. Combined with data from previous investigations of the Lower Miocene from the tropical Atlantic, this research identifies and tests the viability of markers used in current zonation scheme, identifies alternative markers for age boundaries, and examine statistically the most probable order of event in the Lower Miocene using the Ranking and Scaling method (RASC).

The examination of Hole 959A was performed on a 112 samples. Seven additional sites that collectively span the …

Applicability And Estimation Of Error For Determination Of Hydraulic Conductivity Values Based Upon Traditional Aquifer Test Methods For 2-D Groundwater Modeling, Timothy W. Freed Sr.

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The Theis method and its derivative Cooper-Jacob method are commonly used for determining hydraulic conductivity (K) for aquifer studies using two-dimensional (2-D) groundwater modeling. Theis and derivative equations assume isotropic, homogeneous aquifers and horizontal flow. In nature, saturated permeable layers of an aquifer are often separated by less permeable layers or lenses, which commonly have K's that are lower by several orders of magnitude. The presence of such geologic features induces vertical flow during aquifer tests violating assumptions for Theis based methods. This study assesses the appropriateness and error of using Theis based equations to determine K for use in …

Accuracy Assessment Of Aqua-Modis Aerosol Optical Depth Over Coastal Regions: Importance Of Quality Flag And Sea Surface Wind Speed, Jacob Anderson

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Using data collected from 62 coastal stations worldwide from the Aerosol Robotic Network (AERONET) from 2002-2011, accuracy assessments are made for coastal aerosol optical depth (AOD) retrieved from MODIS aboard the Aqua satellite. It is found that coastal AODs (at 550 nm) characterized respectively by the MODIS Dark Land (Land) surface algorithm, the Open Ocean (Ocean) algorithm, and AERONET all exhibit a log-normal distribution. After filtering by quality flags, the coastal MODIS AODs retrieved from the Land and Ocean algorithms are highly correlated with AERONET (with R²≈0.8), but only the Land algorithm AODs fall within the expected error …

Water And Energy Balance Response Of A Riparian Wetland To The Removal Of Phragmites Australis, Phillip Mykleby

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Vegetation and climate both play integral roles in water availability, particularly for arid to semi-arid regions. Changes in these variables can lead to extreme shortages in water for regions that rely on water for crop irrigation (i.e., the Great Plains). The objective of this study is to evaluate the impacts of vegetation on water availability in the Republican River basin in central Nebraska. Decreases in streamflow have been observed in the river basin for many years and, as a result, an invasive riparian plant species (Phragmites australis) is being removed in an effort to reduce evapotranspiration and reclaim …

Variations In Winter Surface High Pressure In The Northern Hemisphere And Climatological Impacts Of Diminishing Arctic Sea Ice, Kristen D. Fox

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

This study explores the role Arctic sea ice plays in determining mean sea level pressure and 1000 hPa temperatures during Northern Hemisphere winters while focusing on an extended period of October to March. This is accomplished by investigating two regions of the same size and comparable climatic zones and elevations in the Northern Hemisphere. A breakdown of 29 years of reanalysis data into average monthly values, anomalies, trends, and comparisons between regions serves as current data to compare with a computer model control run. Ensuring the control run accurately models current atmospheric patterns, altering the model inputs to have no …