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University of Nebraska - Lincoln
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
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- Meteorology (6)
- Climate (4)
- MODIS (3)
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- Thunderstorms (3)
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- Boreal forest (1)
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- Dual-polarimetric radar (1)
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Articles 1 - 23 of 23
Full-Text Articles in Meteorology
A Climatology Of Mesoscale Airmasses With High Theta-E, Charles J. Kropiewnicki
A Climatology Of Mesoscale Airmasses With High Theta-E, Charles J. Kropiewnicki
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
A Mesoscale Airmass with High Theta-E (MAHTE) is a narrow region of larger theta-e located on the cool side of an airmass boundary. MAHTEs typically possesses higher CAPE than the warm side of the boundary, creating a more favorable environment for severe convection. MAHTEs can also be characterized by larger low-level shear and lower LCLs and may also have a propensity for supporting tornadogenesis. The majority of MAHTE research to date has been comprised of case studies, and the prevalence of MAHTEs is not well understood. This project fills that knowledge gap by creating a climatology of MAHTE occurrence. This …
An Empirical Examination Of The Environmental Variability That Impacted Supercell Evolution, Longevity, And Severe Weather Production On 22 May 2019 In Oklahoma, Kyle D. Pittman
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Mesoscale environmental heterogeneity can have significant impacts on thunderstorm organization, evolution, longevity, and severe weather production. This study examines the 22 May 2019 thunderstorm event in Oklahoma, where a relatively broad area of strong instability and vertical wind shear existed along a synoptic boundary and in the open warm sector that would seem to support long-lived supercells and tornadoes. There were two particularly dangerous situation (PDS) tornado watches issued during the event, but few severe reports and no tornadoes formed in the watch that covered the southwestern portion of the state. Several tornadic supercells and many more severe reports occurred …
Radar Signatures In Tropical Cyclone Tornadic And Nontornadic Supercells, Michaela Wood
Radar Signatures In Tropical Cyclone Tornadic And Nontornadic Supercells, Michaela Wood
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Tropical cyclones (TCs) contain highly-sheared environments that are conducive for supercell thunderstorms. These TC supercells sometimes produce tornadoes, often with little warning. Given the often-close proximity of tornadic and nontornadic TC supercells, environments may not be well-distinguished, pointing to the potential value of radar observations. In this study, dual-polarimetric radar signatures of a sample of TC supercells are examined in the context of known supercell structure and microphysics. Tornadic and nontornadic TC supercells are compared with their midlatitude counterparts, and the environments and characteristic structure of these storms are shown to be notably different. An attempt is made to distinguish …
Impacts Of Physical Parameterization Schemes And Soil Moisture Initialization On Boundary Layer Evolution In The Weather Research And Forecasting (Wrf) Model, Grace Cutting
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Numerical weather prediction (NWP) models have become a necessary addition to the atmospheric research community over the last several decades, and atmospheric modeling has been used internationally for numerous operational and research purposes. NWP models contain a vast number of combinations of physical and dynamical parameterization schemes; however, they are not always accurate in forecasting weather phenomena at a particular location, as different combinations of parameterization schemes represent differing conditions. Weather Research and Forecasting (WRF) model simulations were run to explore which of the commonly used planetary boundary layer (PBL) schemes best represented upper-air data (as well as PBL evolution) …
Using Remote And In Situ Observations From Torus To Investigate A Preexisting Airmass Boundary And Its Influence On A Tornadic Supercell On 28 May 2019, Kristen Axon
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
During the 2019 field phase of Targeted Observation by Radars and UAS of Supercells (TORUS), a preexisting airmass boundary was sampled on 28 May 2019 in north-central Kansas in close proximity to a tornadic supercell. This work hypothesized that the preexisting airmass boundary was associated with a mesoscale air mass with high theta-E (MAHTE) that favorably interacted with the tornadic supercell to increase the likelihood of tornadogenesis. Observations from TORUS including mobile mesonets, unoccupied aerial vehicles, soundings, and ground-based mobile radar were used along with GOES-16 visible satellite imagery, Kansas mesonet surface stations, and KUEX WSR-88D data to investigate this …
An Investigation Of Water Obstructions And Related Weather Conditions For Nebraska Roadways, Logan Bundy
An Investigation Of Water Obstructions And Related Weather Conditions For Nebraska Roadways, Logan Bundy
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Roadway resilience across the 10,000 miles of road and 3,500 bridges in Nebraska is critical to the economic success of production and logistics. In a state where historical flooding scenarios, such as the one in March 2019 that caused $150 million in damage, could potentially be increasing, it has become essential to understand the spatial and temporal distribution of high-frequency water obstruction areas on roadways. Using Nebraska Department of Transportation (NDOT) historical water obstruction data from June 2016 through August 2021, statistical and spatial analyses were conducted to quantify the relationship between water obstructions and their associated meteorological conditions, and …
An Observational Study Of Winter Weather-Related Traffic Crashes In Nebraska, Jacob Petr
An Observational Study Of Winter Weather-Related Traffic Crashes In Nebraska, Jacob Petr
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
The responsibilities of meteorologists have evolved over time from simply providing a forecast to needing to also understand how those predictions will impact society and then communicating those risks in a clear, concise, and consistent manner. Increased motor vehicle crash numbers due to adverse weather conditions represent one such impact worthy of further study. Snowfall, in particular, significantly increases the overall risk of a crash, which can result in extensive property damage, severe injuries, and even loss of life.This project seeks to supplement traffic crash information in Nebraska by assessing how snowfall impacts crashes across the state. Crash data were …
Quantification Of Cloud Condensation Nuclei Effects On The Microphysical Structure Of Continental Thunderstorms Using Polarimetric Radar Observations, Kun-Yuan Lee
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Aerosols serving as cloud condensation nuclei (CCN) are crucial to the microphysical structure of thunderstorms. They can also alter the rate of cloud microphysical processes, the moisture profile and the local temperature as a result of latent heating/cooling in the early stage of thunderstorm development. Continental thunderstorms are characterized by high complexity and are highly influenced by environmental conditions. The purpose of this study is to determine the influences of CCN concentration on the microphysics of continental thunderstorms, using a sample of storms from northwestern Oklahoma. The Weather Surveillance Radar-1988 Doppler (WSR-88D) at Vance Air Force Base (KVNX) was upgraded …
Evaluation Of Nocturnal Convective Precipitation Over The Great Plains Using Reanalysis Data And A Wrf-Based Regional Climate Model, Xu Deng
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
This study aims to analyze what processes are mainly responsible for nocturnal convective precipitation during the 1991-2000 period for May-June-July over the Great Plains. Firstly, based on the Weather Research and Forecasting model (WRF) coupled with the NCAR Community Land Model (CLM) and the North American Regional Reanalysis (NARR) reanalysis data, the simulations of the diurnal cycles of LLJ and the convective precipitation are examined. Then, the LLJ-related moisture transport is evaluated since the moisture supply is critical for the development of the heavy rainfall. Results show that the WRF model fails to simulate the nocturnal peak rainfall shown in …
Modeling And Satellite Remote Sensing Of The Meteorological Impacts Of Irrigation During The 2012 Central Plains Drought, Clint Aegerter
Modeling And Satellite Remote Sensing Of The Meteorological Impacts Of Irrigation During The 2012 Central Plains Drought, Clint Aegerter
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
As irrigation is increasingly needed for agricultural production, it is becoming progressively more important to understand not only how irrigation impacts water availability, but how the introduction of this water into the soil impacts weather and climate through land-atmosphere interactions. In the summer of 2012, the Central Plains of the United States experienced one of its most severe droughts on record. This study examines the meteorological impacts of irrigation during this drought through observations and model simulations using the Community Land Model (CLM) coupled to the Weather Research and Forecasting (WRF) model. A simple parameterization of irrigation processes is added …
Springtime Melt Onset On Arctic Sea Ice From Satellite Observations And Related Atmospheric Conditions, Angela C. Bliss
Springtime Melt Onset On Arctic Sea Ice From Satellite Observations And Related Atmospheric Conditions, Angela C. Bliss
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
The timing of snowmelt onset (MO) on Arctic sea ice derived from passive microwave satellite data is examined by determining the melting area (in km2) on a daily basis for the spring and summer melt season months over the 1979 – 2012 data record. The date of MO on Arctic sea ice has important implications for the amount of total solar energy absorbed by the ice-ocean system in a given year. Increasingly early mean MO dates have been recorded over the 34-year data record as evidenced by statistically significant trends of 6.6 days decade-1 over the extent …
Verification And Analysis Of Impact-Based Tornado Warnings In The Central Region Of The National Weather Service, Holly B. Obermeier
Verification And Analysis Of Impact-Based Tornado Warnings In The Central Region Of The National Weather Service, Holly B. Obermeier
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Tornado warnings are one of the most critical products issued by the National Weather Service (NWS), and favorable verification statistics are desirable. The 2011 NWS statistics for traditional tornado warnings indicate that the probability of detection (POD) is 70%, while the false alarm rate (FAR) is 76%. The recent Joplin, Missouri EF5 tornado event on 22 May 2011, which resulted in massive devastation and loss of life, prompted the NWS to re-evaluate the current tornado warning format. After the Joplin, MO event, the Central Region of the NWS implemented the impact-based tornado warning (IBTW) experiment in 2013. IBTWs consist of …
Eastern Us Dryline Climatology And Synoptic-Scale Environment, Rebecca S. Duell
Eastern Us Dryline Climatology And Synoptic-Scale Environment, Rebecca S. Duell
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
The dryline is an important focal point for convection initiation, and the subject of many studies. While the most common location for drylines is the southern Great Plains, dryline passages and subsequent severe weather outbreaks have been documented in the Mississippi River Valley and into portions of the southeastern United States. Little is known about these “eastern” drylines or how often they occur, as no climatologies or detailed studies have been published on them. This thesis presents a fifteen-year climatology (1999-2013) of eastern drylines in an effort to identify how often and where they typically occur, and to identify synoptic …
Springtime Atmospheric Responses To North Atlantic Sst Anomalies In Idealized Gcm Experiments: Northern Hemisphere Circulation And North American Precipitation, Michael C. Veres
Springtime Atmospheric Responses To North Atlantic Sst Anomalies In Idealized Gcm Experiments: Northern Hemisphere Circulation And North American Precipitation, Michael C. Veres
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
In this study, a series of experiments using idealized sea surface temperatures (SST), land and orography are performed to examine the interactions between the Atlantic Multidecadal Oscillation (AMO), continents and major orography. Three sets of experiments are done using an increasingly realistic surface boundary (aqua-planet, land without orography and land with orography) and run using perpetual equinox conditions. For each land surface boundary, the model is forced with a zonally symmetric SST, with additional experiments with an imposed positive or negative SST anomalies in the North Atlantic. The experiments are then compared to determine how these forcings interact and what …
Mesoscale Modeling And Satellite Observation Of Transport And Mixing Of Smoke And Dust Particles Over Northern Sub-Saharan African Region, Zhifeng Yang
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
The transport and vertical distribution of smoke and mineral dust aerosols over the Northern Sub-Saharan African (NSSA) region have important implications for regional and global air quality and climate. This study employs ground-based and satellite observations, and numerical simulations conducted with a fully-coupled meteorology-chemistry-aerosol model, Weather Research and Forecasting model with Chemistry (WRF-Chem). The WRF-Chem simulation is for February 2008 and uses hourly dynamic smoke emissions from the Fire Locating and Modeling of Burning Emissions (FLAMBE) database derived from Moderate Resolution Imaging Spectroradiometer (MODIS) fire products. Model performance of smoke and dust simulation is evaluated using numerous satellite and ground-based …
An Examination Of The Mechanisms And Environments Supportive Of Bow Echo Mesovortex Genesis, George Limpert
An Examination Of The Mechanisms And Environments Supportive Of Bow Echo Mesovortex Genesis, George Limpert
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Low-level mesovortices are associated with enhanced surface wind gusts and high-end wind damage in quasi-linear thunderstorms. Although damage associated with mesovortices can approach that of moderately strong tornadoes, skill in forecasting mesovortices is low. The overarching goal of this work is to understand mesovortices and how they develop, to improve the skill in forecasting them. This was done by developing a climatology of mesovortices, which required a tracking algorithm, and numerical simulations were conducted to answer questions that could not be answered through the observational data. A climatology of mesovortices was constructed from 44 events during 2009 and 2010 to …
Remote Sensing Of Surface Visibility From Space: A Look At The United States East Coast, Amy L. Kessner
Remote Sensing Of Surface Visibility From Space: A Look At The United States East Coast, Amy L. Kessner
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
While important for the management of air quality, human health and transportation, surface visibility data currently are only available through ground-based measurements, such as the Automated Surface Observing System (ASOS), and therefore lack spatial coverage. In analogy to the recent work of using satellite-based aerosol optical depth (AOD) to derive surface dry aerosol mass concentration at continental-to-global scale for cloud-free conditions, this study evaluates the potential of AOD retrieved from the MODerate Resolution Imaging Spectroradiometer (MODIS) for deriving surface visibility. For this purpose of evaluation, the truncated and discrete visibility data from daily weather reports are not suitable and the …
An Analysis Of Deep Convection Initiation Environments, Noah Lock
An Analysis Of Deep Convection Initiation Environments, Noah Lock
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Initiation is the part of the convective life cycle which is currently least understood and least well forecast. The inability to properly forecast the timing and/or location of deep convection initiation degrades forecast skill, especially during the warm season. The goals of this research are examine the spatiotemporal distribution of thunderstorm initiation points and to determine which atmospheric parameters (and ultimately processes) are most important for the initiation of thunderstorms. The spatiotemporal distribution of thunderstorm initiation points shows the expected peaks during summer and during the afternoon. The warm season also produces significant concentrations of initiation points near mountains, mainly …
Retrieval Of Sub-Pixel-Based Fire Intensity And Its Application For Characterizing Smoke Injection Heights And Fire Weather In North America, David Peterson
Retrieval Of Sub-Pixel-Based Fire Intensity And Its Application For Characterizing Smoke Injection Heights And Fire Weather In North America, David Peterson
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
For over two decades, satellite sensors have provided the locations of global fire activity with ever-increasing accuracy. However, the ability to measure fire intensity, know as fire radiative power (FRP), and its potential relationships to meteorology and smoke plume injection heights, are currently limited by the pixel resolution. This dissertation describes the development of a new, sub-pixel-based FRP calculation (FRPf) for fire pixels detected by the MODerate Resolution Imaging Spectroradiometer (MODIS) fire detection algorithm (Collection 5), which is subsequently applied to several large wildfire events in North America. The methodology inherits an earlier bi-spectral algorithm for retrieving sub-pixel …
Periodicities Of Peak Current And Flash Multiplicity In Cloud To Ground Lightning, Alexander R. Gibbs
Periodicities Of Peak Current And Flash Multiplicity In Cloud To Ground Lightning, Alexander R. Gibbs
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Research on lightning has been conducted on various topics including thunderstorm electrification and climatology of lightning strikes however; there are still some characteristics of lightning that are not well known, such as flash multiplicity and peak current as a function of individual thunderstorms. These characteristics are the leading cause of injuries and damage each year. This study examines a severe weather event in Minnesota on 16 September 2006, in order to determine what may cause peak current and flash multiplicity. Cycles in peak current and flash multiplicity are identified and then associated with CAPE to determine if a thunderstorm’s updraft …
Water And Energy Balance Response Of A Riparian Wetland To The Removal Of Phragmites Australis, Phillip Mykleby
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 …
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 …
Impacts Of Meteorological Factors On Modis-Observed Fire Activity In The North American Boreal Forest: The Role Of Lightning, David A. Peterson
Impacts Of Meteorological Factors On Modis-Observed Fire Activity In The North American Boreal Forest: The Role Of Lightning, David A. Peterson
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
The meteorological impact on wildfire activity in the North American boreal forest during the fire seasons of 2000 – 2006 is statistically analyzed through an integration of the following data sets: the MODerate Resolution Imaging Spectroradiometer (MODIS) level 2 fire products, the 3-hourly 32-km gridded meteorological data from North American Regional Reanalysis (NARR), the instantaneous lightning data collected by the Canadian Lightning Detection Network (CLDN), and the Alaska Lightning Detection Network (ALDN). Positive anomalies of the 500 hpa geopotential height field, convective available potential energy (CAPE), number of cloud-to-ground lightning strikes, and the number of consecutive dry days are found …