Oceanography and Atmospheric Sciences and Meteorology Commons^™

Crustal Structure Of The Vøring Plateau And Vøring Spur From Joint Refraction And Reflection Travel-Time Tomography, Anika Nawar Mayeesha

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

Crustal architecture of the Vøring Plateau and Vøring Spur in the mid-Norwegian continental margin remains debated because the geophysical data in the area do not uniquely constrain whether the crust is continental, oceanic, or transitional. This study reanalyzes wide-angle ocean-bottom seismometer data from Profile 11-03 across the Vøring passive continental margin using joint travel-time tomography of crustal refractions and Moho reflections. A total of 6,760 first-arrival picks and 542 PmP picks from sixteen instruments were inverted for P-wave velocity and reflector depth. Three starting models were inverted independently to test sensitivity to the initial crustal configuration. The first two used …

Observing System Simulation Experiments To Investigate Impacts Of Deep-Tropospheric Uas Flights On Forecasts, Kenneth Alexander Swan

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

Uncrewed aircraft systems have emerged as a promising option to address meteorological gaps in observations in the lower troposphere. With recent advancements, UAS may be able to address gaps aloft in areas that lack coverage from radiosondes and commercial aircraft. UAS have shown the potential to significantly benefit NWP forecasts from profiles in the lowest 2 km AGL, but the impact of UAS profiles to the tropopause has yet to be quantified. Additionally, the impacts of hazardous flying conditions that UAS would encounter need to be addressed to guide future UAS capabilities. To address these questions, we designed an observing …

Examining Extremes: A Comparison Between Machine Learning Based Southwestern Conus Seasonal Drought And High Fire Risk Event Synoptic Climatologies, Ethan M. Greenberg

School of Natural Resources: Dissertations, Theses, and Student Research

The Southwestern United States (SW CONUS), comprised of California, Arizona, Nevada, and Utah, is a vast region that tens of millions of people call home. Hosting ecosystems ranging from grasslands and shrublands to temperate forests and climate zones ranging from Mediterranean climates to arid deserts, the region is nearly unanimously prone to intense droughts and devastating wildfires. While fire weather conditions and drought are often studied separately or mentioned as background conditions for the other, there are relatively few studies that compare the typical meteorological conditions between the two. This study aims to more closely understand the meteorological relationship between …

Spatiotemporal Variability Of Differential Reflectivity (Zdr) Columns Due To Environment In Tornadic And Nontornadic Supercells, Adrianne J. Engel

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

Polarimetric signatures have been of interest to researchers and operational forecasters since the completion of the WSR-88D network upgrade in 2013. Differential reflectivity (Z_DR) columns, which are collocated with supercell updrafts, are the focus of this study. Microphysical distributions within these signatures can be used to infer updraft strength and elucidate the processes responsible for updraft intensity and evolution. Z_DR column depth, areal extent, and variability of these metrics through space and time are assessed in a dataset of 114 nontornadic and tornadic supercells. Means of column metrics in nontornadic, non-tornado-producing, and tornado-producing analysis times are evaluated …

Comparing Awssi And Traditional Winter Metrics For Predicting Overwinter Survival Of Juvenile Walleye (Sander Vitreus), Camille N. Shifrin

Honors Program: Senior Projects (Public)

Winter conditions are an important driver of recruitment variability in freshwater fishes, yet winter severity is often characterized using single climate metrics. These simplified approaches may not capture the cumulative stress experienced by fishes during winter. The Accumulated Winter Season Severity Index (AWSSI) integrates multiple components of winter climate and may therefore provide a more biologically relevant indicator of overwinter survival. In this study, we compared AWSSI with traditional winter severity metrics to explain interannual variation in overwinter survival of juvenile Walleye (Sander vitreus) in Harlan County Reservoir, Nebraska. Model comparisons using Akaike’s Information Criterion (AIC) indicated that …

Impact Of In Situ Observations From Three Torus Cases On Model Analyses And Forecasts Of Severe Convection, Robert M. Szot

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

The quality of forecasts of severe deep convection in high-resolution numerical weather prediction is dependent on the representativeness of the model initial conditions. This representativeness may be negatively impacted by limited observation availability and by the presence of mesoscale heterogeneities that were not detected by conventional observations assimilated into convection-allowing models. By assimilating storm-scale observations from the Targeted Observation by Radars and Uncrewed Aircraft Systems (UAS) of Supercells (TORUS) campaign into an ensemble styled after the Warn-on-Forecast System, this study aims to investigate if data from field work platforms can improve the quality of initial conditions in the ensemble, potentially …

Assessment Of Soybean Response To Irrigation Variability In Eastern Nebraska Using The Aquacrop Model, Anmol Singh, Saleh Taghvaeian, Yufeng Ge, Derek M. Heeren, Frank Bai

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Soybean [Glycine max (L.) Merr.] is a major irrigated crop in eastern Nebraska, where recent expansions in irrigated agriculture and projected trends in irrigation demand necessitate thorough investigations of approaches that can optimize its irrigation management. In this study, the AquaCrop model was calibrated and validated using 19 variable irrigation treatments from a five-year field experiment. The model accurately simulated canopy cover, soil water content, and grain yield, with validation normalized root mean square error (nRMSE) of 12%, 7%, and 7%, respectively. The model was subsequently applied to estimate soybean yield and water requirement during a 15-year period (2010–2024) …

Pymelt-Px: A Python Script For Modeling Melting Of A Pyroxenite-Peridotite Bilithological Mantle, Ana L. Jimenez Bustos

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

The study of oceanic crust formation is a fundamental building block in our understanding of the processes of planetary formation, necessitating an understanding of the melt generation processes that help form oceanic crust. To aid in this purpose, we present pyMeltPX: a bilithological pyroxenite-peridotite mantle modeling script. Although the mantle is primarily comprised of peridotite, pyroxenite is a minor but ubiquitous feature of the mantle and can contribute a disproportionate amount of melt to crustal generation in mid-ocean ridge and ocean island basalt settings. Our model, pyMeltPX, is a python coded, extensible tool based on the Excel calculator by Lambart …

Flood Resilience Through Working-Land Conservation: Assessment Of Wetland Inundation Dynamics Across Wrp, Wma, Wpa, Padus And Crp Lands In Nebraska (2018–2024), Pranjay Joshi

Community and Regional Planning Program: Theses

This study first confirms whether Nebraska’s wetlands are still functioning hydrologically in ways that reduce flood impacts. Wetlands are known to lessen flood damage by storing water, slowing runoff, and moderating peak flows, but these benefits depend on the wetlands’ ability to maintain inundation and saturation through time. Many wetlands across the state have undergone drainage, hydrologic alteration, or isolation from surrounding watersheds, raising uncertainty about their present-day functioning. Using seven years of Sentinel-2 imagery processed in Google Earth Engine, this research establishes a clear, long-term record of inundation patterns across thousands of wetland parcels. This analysis verifies which wetlands …

An Integrated Modeling Framework To Evaluate Circularity Of The Corn–Water–Ethanol–Beef Nexus, Heydi Han

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This dissertation examines the transition from conventional linear agricultural and food bioenergy systems toward more circular, resilient, and resource-efficient configurations. Prior research indicates that spatial and temporal variability in soil, weather, animal biological responses, and management decisions strongly influences productivity, nutrient-use efficiency, and profitability. Studies have also shown that a diversified circular system can buffer these sources of variability, improving stability and adaptive capacity. Building on these insights, the central focus of this work is to develop an integrated modeling framework to evaluate circularity within the Corn-Water-Ethanol-Beef (CWEB) nexus and explore how climate variability and management choices shape system-wide performance. …

Rainfall-Runoff Modelling In An Indonesian Humid Tropical Area Using Satellite-Based Precipitation Products, Noordiah Helda

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This dissertation explores three rainfall-runoff models in the humid tropical regions of Indonesia using satellite-based precipitation products (SBPPs) and develops integrated machine-learning modeling frameworks. Several ground-based observations from BMKG (Badan Meteorologi, Klimatologi, dan Geofisika (also known as the Indonesian Agency for Meteorology, Climatology, and Geophysics)) stations across Indonesia (133−165 stations) are compared and evaluated against satellite products, indicating that GPM performs well, with R-squared values ranging from 0.54 to 0.76 and correlation coefficients ranging from 0.45 to 0.69, respectively.

In the Martapura Watershed, South Kalimantan, due to a lack of observational discharge data, streamflow was generated using the FJ Mock …

Modeling The Greenland-Iceland-Faroe Ridge Using Integrated Geophysical Analysis, Zachary Clowdus

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

The Greenland-Iceland-Faroe Ridge (GIFR) is an area of significant geologic interest with anomalously thick crust related to enhanced melt generation from the interaction between the Mid-Atlantic Ridge and the Iceland hotspot. To the northeast of Iceland lies the Jan Mayen Microcontinent (JMMC), which is a continental fragment separated from Greenland during the opening of the Northern Atlantic. The overall extent of the JMMC, especially its southern boundary, remains poorly constrained. The crust beneath the GIFR is believed to be primarily of oceanic affinity. However, a recent discovery of felsic lavas in Iceland led to an alternative hypothesis that implies the …

The Urban Heat Island And Its Role In Shaping Convective Environments: An Observational Study, Benjamin W. Moll

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

The continued spread of urbanization and its well-documented effects on regional weather and climate necessitate further research. Urban environments are often warmer and drier than their rural surroundings. This trade-off between a warmer but drier environment could have a complex impact on deep convection and its initiation. Previous studies have noted significant changes in precipitation patterns around cities as well as changes to ongoing deep convection. Given the well-documented theory and past research, it is hypothesized here that urban areas have a significant impact on the PBL thermodynamics of convective environments. The urban heat island (UHI) component of the Micro …

Occurrence Of Per And Polyfluoroalkyl Substances In Rural Wastewater Treatment Plants And Comparison To Large Treatments Plants, Madeleine Rauhauser

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Per and polyfluoroalkyl substances (PFAS) are a class of compounds defined by their carbon – fluorine bonds, which are incredibly strong. The strength of this bond makes these compounds very useful industrially, they are used as waterproof and grease proof coatings, and as fire retardants. The same thing that makes them useful industrially makes them incredibly recalcitrant in the environment, it is difficult to destroy these compounds. PFAS are also suspected to cause health impacts in people, such as kidney cancer and low birth weights. Wastewater has been commonly identified as a contributor to the amount of PFAS in the …

Stable Isotope Paleoecology In The Bridgerian (Early Eocene): Investigation Of The Bridgerian Crash And The Canopy Effect, Aaron M. English

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

The Early Eocene Climatic Optimum (EECO) was the warmest sustained interval of the Cenozoic. Its waning stages coincided with a marked decline in mammalian biodiversity known as the Bridgerian Crash, which was likely driven by increasingly cooler and drier conditions. Paleobotanical evidence suggests the early Eocene supported wet, subtropical to tropical forests at mid-latitudes, however the structure of these forests at the close of the EECO remains poorly understood. In this study, I measure carbon isotope values (d¹³C_E) from the enamel of early Bridgerian (~52.2 – 48.3 Ma) herbivorous mammals from the Greater Green River …

Understanding And Assessing Climate Change: Preparing For Nebraska’S Future, 2024 Climate Change Impact Assessment Report, Deborah J. Bathke, Eric Hunt, Heather Akin, Andrea D. Basche, Jesse E. Bell, Daniel R. Dileo, Ross Dixon, Martha Durr, Tonya Haigh, Francis John Hay, Kristina W. Kintziger, Nicholas A. Mcmillan, Hank Miller, Jerome Okojokwu-Idu, Crystal Powers, Tirthankar Roy, Zhenghong Tang, W. Ryan Wishart, Aaron R. Young, Sarah A. Sonsthagen, Jonathan J. Spurgeon

School of Natural Resources: Faculty Publications

Contents

Report Team

Acknowledgments

Executive Summary

Introduction

Climate Change Contexts: Global, National, and State

Observed Changes in Nebraska's Climate

Projections of Nebraska's Future Climate

Water Systems

Energy

Ecosystems

Agriculture

Human Health

Communities and the Built Environment

Indigenous Peoples

Climate Justice and Equity

The Response of Faith Communities

Nebraskans' Perceptions of Climate Change

Next Steps and Future Work

Supplemental Report: Adaptation, Risks, and Impacts

About the Authors

Faith-based Communities Survey

Evaluated Plans and Assessments

References

Low-Level Polarimetric Signatures Of Supercells During Ef3+ Tornado Production, Anthony Noah Began

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

Most EF3+ tornadoes are produced by supercells. Understanding of microscale features surrounding intense tornado production remains limited. This research aims to determine commonalities in low-level microphysical processes during intense tornado production via polarimetric radar signature assessment with a Python-based algorithm. Polarimetric variables hypothesized to reflect low-level wind profiles such as the differential reflectivity (Z_DR) arc and the Z_DR–K_DP (specific differential phase) separation vector will be investigated. Supercells which produced EF3+ tornadoes will be examined since these tornadoes pose the highest threat. From 2010 to 2024, the United States recorded approximately 19,100 tornadoes which resulted in …

Evaluation Of Performance Characteristics And Groundwater Contamination Risks Associated With On-Farm Swine Carcass Disposal Via Composting And Shallow Burial With Carbon, Gustavo Castro Garcia

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This dissertation evaluates the performance of three on-farm swine carcass disposal methods: whole carcass composting (WCC), ground carcass composting (GCC), and shallow burial with carbon (SBC), focusing on biosecurity factors and groundwater contamination risks. Foreign animal diseases (FADs), such as African swine fever and classical swine fever, pose severe economic and animal well-being risks if introduced to the United States. With confirmation of an FAD, swine movement will be halted, creating an urgent need for practical, biosecure, and environmentally responsible on-farm disposal strategies for swine carcasses. Nebraska, as a leading swine-producing state, exemplifies the vulnerability of high-density livestock regions to …

Environmental Controls Of Hail In Quasi-Linear Convective Systems, Cameron A. Barker

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

A study of hail occurrence in quasi-linear convective systems (QLCS), as well as severe weather parameters contributing to the likelihood and intensity of hail, is presented. Rapid Refresh (RAP) proximity soundings for 218 QLCS events from 2012 to 2022 are selected to sample QLCS environments near peak intensity. Study objectives are to assess common environmental parameter spaces that favor hail in QLCSs while connecting these findings to results for supercells. Hail occurrence is also examined in terms of synoptic regime.

Six synoptic regimes were identified to support QLCSs with hail, from high shear, low cape (HSLC) to low shear, high …

Surveys And Modeling: Using An Existing Survey To Describe And Compare Populations To Better Inform On Groundwater Model Inputs, M. Austin Wise

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

The Mississippi River Valley “Alluvial Aquifer” is among the most agriculturally significant aquifers in the United States. However, parts of the aquifer are exceeding sustainable yield as development of the water source continues. Survey research in other aquifers, such as the High Plains (Ogallala) Aquifer, has helped to understand the perceptions and attitudes of irrigators withdrawing from their aquifers. This led to numerous questions: What are the attitudes of irrigators in the Alluvial Aquifer region? How do they compare to irrigators in other regions of the country? Can their intentions be used to generate more accurate inputs when modeling adoption …

Exploring The Application Of Repeated Microgravity Surveys To Monitor Groundwater Level Variations In Nebraska, Kaitlin M. Steinauer

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

Groundwater is an important resource in the state of Nebraska for supporting industries and ecosystems. Monitoring this vast resource ensures its continued availability for generations to come. However, monitoring utilizes well data, and if a well is not present in a desired location, geophysical methods can be explored. This project tests the capability of repeated gravity surveys over Nebraska’s aquifers to monitor groundwater levels throughout 2024.

Two study areas were selected in Eastern Nebraska. The first is in Oakland, Nebraska, over a confined aquifer system. The second is in Plymouth, Nebraska, and exhibits unconfined conditions. Four sites were chosen to …

Drift Dynamics Of Early Life-Stage Invasive Carps, Saurav Karki

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Asian carp species pose significant ecological threats to North American freshwater systems due to their invasive nature and prolific reproduction. Their semi buoyant eggs develop while drifting downstream with the river current. Understanding early life-stage transport is therefore critical for predicting recruitment potential and guiding management efforts. Existing fluvial egg drift models, including those relying on 1-D hydraulics and fully 3-D CFD-based models, are either inadequate for complex braided rivers or too computationally demanding for large-scale application. The Platte River in Nebraska, characterized by wide, shallow, multi-threaded channels, is dominated by two-dimensional flow conditions, making a depth-averaged 2-D modeling approach …

Development And Evaluation Of Supported Ionic Liquid Membrane And Porphyrin Frameworks For Carbon Capture Separation, Sarang Ismail

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

The global urgency to mitigate anthropogenic CO₂ emissions has intensified the pursuit of energy-efficient separation technologies. Supported Ionic Liquid Membranes (SILMs) have emerged as promising candidates for CO₂ capture due to their tunable solubility-selectivity and low energy requirements. However, challenges such as mechanical instability, limited scalability, and trade-offs in transport performance have impeded their widespread adoption.

This thesis explores a systematic approach to designing and optimizing SILMs for enhanced CO₂ separation by tailoring polymer–ionic liquid interactions, processing conditions, and material architectures. A comprehensive set of studies were conducted using poly(vinylidene fluoride) (PVDF) with varying molecular weights, different grades of PEBAX®, …

Response Of Soybean To Variable Irrigation Levels In Eastern Nebraska Using The Aquacrop Model, Anmol Singh

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

AquaCrop was calibrated and validated for soybean [Glycine max (L.) Merr.] using 19 irrigation treatments from five years using data from field experiments. The model accurately simulated canopy cover (CC), soil water content (SWC), and grain yield, with overall validation nRMSE values of 12%, 7%, and 7%, respectively. The overall validation nRMSE for SWC in individual 30-cm soil layers was comparatively higher, at 19%. The model was subsequently applied for long-term simulations (2010–2024) to estimate soybean yield and water requirements for two dominant soil types, Yutan silty clay loam and Tomek silt loam under three irrigation levels - rainfed, …

A Uas-Centered Investigation Of Vorticity Characteristics And Cold Pool Structure Across Forward And Left-Flank Boundaries In Supercells, Mark R. De Bruin

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

Supercell internal boundaries are the locus of tornadogenesis; thus, understanding the characteristics of these boundaries, particularly in terms of vorticity, is important for identifying the role they play in tornado formation. Insight into the overall characteristics of internal boundaries and their possible role in tornadogenesis have been driven by studies reliant on numerical modeling-based experiments. Observational studies often neglect above-surface conditions or, when these observations are made, lack the spatial resolution to resolve boundary characteristics. During TORUS (Targeted Observation by Radars and UAS of Supercells) 2019 and TORUS-LItE (TORUS Left-flank Intensive Experiment) 2023, uncrewed aircraft systems (UAS) and mobile mesonets …

A Study Of Ice And Fire: Environmental Change Impacts On Lakes Of The Nebraska Sandhills, Daniel Gschwentner

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

The Nebraska Sandhills contain thousands of shallow, groundwater-fed lakes. These lakes are extremely sensitive to environmental and climatic changes due to their isolated hydrological setting and small volume. Building on previous work on the hydrology, geochemistry and long-term climate response of Sandhill lakes, my research considers how ecosystem processes such as primary production, nutrient limitation and water quality respond to short-term environmental and climatic change. In my first data chapter, I highlight that Sandhill lakes are nitrogen (N) but not phosphorus (P) limited and that N:P ratios are poor predictors of nutrient limitation status in Sandhill lakes. In my second …

Simulations Of Differential Reflectivity Columns In Quasi-Linear Convective Systems, Devon Jacob Healey

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Much research over the past decade has revealed that dual-polarization radar is a powerful tool in furthering our understanding of severe storm dynamics and subsequently improving warning strategies for these hazardous events. However, there are currently very few studies examining a particularly prolific severe convective storm mode with dual-polarization radar: quasi-linear convective systems (QLCSs). These storms can occur in any season of the year throughout most of the contiguous United States and can have immense societal impacts. Warning for the hazards produced by QLCSs is currently a significant operational challenge, therefore, research is needed to see if applying dual-polarization radar …

Optimizing Nitrogen Management: Assessing Nitrate Transport In The Deep Vadose Zone And Its Impact On Groundwater Quality In East-Central Nebraska, Muili O. Lawal

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Groundwater contamination by nitrate (NO₃-N) is a growing environmental and public health concern driven largely by intensive agricultural fertilizer applications. The vadose zone plays an important role in NO₃-N transport, influencing groundwater quality and agricultural sustainability. This study investigated NO₃-N leaching dynamics in the deep vadose zone of Water Quality Sub-Area 30 (WQA30) within the Lower Loup Natural Resources District (LLNRD), northeast of Columbus, Nebraska (mean groundwater NO₃-N: 20.3 mg/L), using soil cores from 16 shallow (to 6.1 m) and four deep (down to 25.9 m) across four zones, two with inorganic fertilizer (Zones 1 and 4) and two with …

Assessment Of Sampling Gears For Bigheaded Carp In Mid-Order Prairie Rivers In Nebraska, Brett M. Anderson

School of Natural Resources: Dissertations, Theses, and Student Research

Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis (collectively bigheaded carp) have invaded tributaries to the Missouri River and Platte River in Nebraska, USA. Information pertaining to efficient sampling protocols for assessing bigheaded carp populations as well as benefiting removal efforts is needed. Herding is a method used to increase the capture efficiency and detection probability of adult bigheaded carp by simultaneously using active and passive sampling gears. During June-July 2023, four herding techniques were assessed regarding their ability to elicit directional movement past an enclosure gate. The combination of sound and electrofishing resulted in the highest mean …

Radar Precursors To Severe Weather Reports In Left-Moving Supercells, Eric A. Carothers

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

While much research has examined dual-polarimetric signatures of right-moving supercells, very little has been done with left-moving supercells. Given that left-moving supercells are thought to be disproportionate producers of large hail, understanding their internal dynamics is vitally important. This study examines differences and trends in the dual-polarimetric signatures of left-moving supercells to identify precursors to severe weather reports. A dataset of left-moving supercells associated with severe weather reports was created. These storms are processed with an automated analysis algorithm that identifies and quantifies the polarimetric signatures in each storm. A method for analysis of differences and trends in their dual-polarization …