Physical Sciences and Mathematics Commons^™

Exploring Background Noise With A Large-N Infrasound Array: Waterfalls, Thunderstorms, And Earthquakes, L. T. Scamfer, J. F. Anderson

Geosciences Faculty Publications and Presentations

Ambient infrasound noise contains an abundance of information that is typically overlooked due to limitations of typical infrasound arrays. To evaluate the ability of large-N infrasound arrays to identify weak signals hidden in background noise, we examine data from a 22-element array in central Idaho, USA, spanning 58 days using a standard beamforming method. Our results include nearly continuous detections of diverse weak signals from infrasonic radiators, sometimes at surprising distances. We observe infrasound from both local (8 km) and distant (195 km) waterfalls. Thunderstorms and earthquakes are also notable sources, with distant thunderstorm infrasound observed from ∼800 to 900 …

Comparing Composite Severe Weather Indices Of Thunderstorm Activity On Sea-Breeze And Non-Sea-Breeze Days In The Mobile, Alabama Area, Elizabeth Seiler

Poster Presentations

Poster for the Honors Thesis project.

Sea breezes (SB) occur frequently from May through October along the U.S. Gulf of Mexico Coast. One reason why SBs interest forecasters is their ability to spawn summertime thunderstorms, which can cause flash flooding, lightning, and hail. However, forecasting the exact timing and location of SB-driven convection can be challenging. This thesis will focus on Mobile and Baldwin Counties in southwest Alabama, which experience two types of phenomena – SBs along the Gulf of Mexico Coast and bay breezes on either side of Mobile Bay. Over the past years, multiple undergraduate students have analyzed …

Trends In Observed And Simulated Radar Reflectivity For The 21st Century, Christopher Michael Battisto

Graduate Research Theses & Dissertations

The effects of climate change may influence the prevalence of regional atmospheric conditions supportive of hazardous convective weather (HCW). As a result, the possibility of an increase in the frequency, strength, and/or variability of thunderstorms and their high-impact hazards—including tornadoes, damaging winds, hail, and flash flood-producing downpours—has garnered much scientific and public interest. Radar reflectivity, which remotely assesses precipitation intensity, may be used to detect, track, catalog, and appraise HCW and their parent storms over broad spatiotemporal scales. Reflectivity may also be simulated with regional climate models, and recent, but limited, efforts using these simulation output have identified the potential …

Examining Terrain Effects On Upstate New York Tornado Events Utilizing High-Resolution Model Simulations, Luke Lebel

Atmospheric & Environmental Sciences

The region at the intersection of the Mohawk and Hudson valleys of New York is characterized by complex terrain. It has been hypothesized that this complex terrain may have an impact on the development and evolution of severe convection in the region. Specifically, previous research has hypothesized that terrain-channeled flow in the Hudson and Mohawk valleys contributed to increased low-level wind shear and instability in the valleys during past severe weather outbreaks. However, a lack of observations in the region prevented this hypothesis from being robustly tested.

The goal of this study is to further examine this hypothesis and complement …

The Influence Of Isolated Thunderstorms And The Low-Level Wind Field On Nocturnally Migrating Birds In Central North America, Matthew V.D. Broeke, Timothy J. Gunkel

Department of Earth and Atmospheric Sciences: Faculty Publications

Seasonal bird migration occurs on large spatial scales and is influenced by many factors including weather conditions. Weather can include thunderstorms, which may force migrants to land or cause them to reroute a migration path. In this study, a sample of isolated thunderstorms was analyzed from the domains of three weather radars in the central United States to test hypotheses regarding the influence of thunderstorms on the distribution of migrants. Migrating bird density was often reduced in the wake of storms, and this wake reduction was typically more pronounced for larger, more intense and faster- moving storms, particularly in eastern …

The Influence Of Isolated Thunderstorms And The Low-Level Wind Field On Nocturnally Migrating Birds In Central North America, Matthew S. Van Den Broeke, Timothy J. Gunkel

Department of Earth and Atmospheric Sciences: Faculty Publications

Seasonal bird migration occurs on large spatial scales and is influenced by many factors including weather conditions. Weather can include thunderstorms, which may force migrants to land or cause them to reroute a migration path. In this study, a sample of isolated thunderstorms was analyzed from the domains of three weather radars in the central United States to test hypotheses regarding the influence of thunderstorms on the distribution of migrants. Migrating bird density was often reduced in the wake of storms, and this wake reduction was typically more pronounced for larger, more intense and faster- moving storms, particularly in eastern …

Gamma Ray Flashes Produced By Lightning Observed At Ground Level By Tetra-Ii, D. J. Pleshinger, S. T. Alnussirat, J. Arias, S. Bai, Y. Banadaki, M. L. Cherry, Anderson Sunda-Meya

Faculty and Staff Publications

In its first 2 years of operation, the ground-based Terrestrial gamma ray flash and Energetic Thunderstorm Rooftop Array (TETRA)-II array of gamma ray detectors has recorded 22 bursts of gamma rays of millisecond-scale duration associated with lightning. In this study, we present the TETRA-II observations detected at the three TETRA-II ground-level sites in Louisiana, Puerto Rico, and Panama together with the simultaneous radio frequency signals from the lightning data sets VAISALA Global Lightning Dataset, VAISALA National Lightning Detection Network, Earth Networks Total Lightning Network, andWorld Wide Lightning Location Network. The relative timing between the gamma ray events and the lightning …

The Role Of Boundary-Parallel Vertical Wind Shear In Convection Initiation, Alexander J. Krull

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

Convection initiation (CI) remains a forecasting challenge for meteorologists. CI frequently occurs within the vicinity of some airmass boundary or density current. Airmass boundaries are favored areas of convergence, thus associated forced ascent facilitates CI. Features such as misocyclones often develop along the leading edge of airmass boundaries, favoring updraft formation and prompting alterations to the horizontal and vertical flow near the boundary. Airmass boundary characteristics and CI potential have been found to be sensitive to the environmental vertical wind shear. This affects propagation speed, convergence, and thus forced ascent along the leading edge. Previous studies have focused primarily on …

A Diagnostic Examination Of The Eastern Ontario And Western Quebec Wintertime Convection Event Of 28 January 2010, Shawn M. Milrad, John R. Gyakum, Eyad H. Atallah, Jennifer F. Smith

Shawn M. Milrad

The priority of an operational forecast center is to issue watches, warnings, and advisories to notify the public about the inherent risks and dangers of a particular event. Occasionally, events occur that do not meet advisory or warning criteria, but still have a substantial impact on human life and property. Short-lived snow bursts are a prime example of such a phenomenon. While these events are typically characterized by small snow accumulations, they often cause very low visibilities and rapidly deteriorating road conditions, both of which are a major hazard to motorists. On the afternoon of 28 January 2010, two such …

A New Analysis Of The Gálvez-Davison Index For Convective Forecasts In Northern Africa, Gabriel D. Donndelinger

Theses and Dissertations

Severe wind gusts and thunderstorms have been difficult to forecast in Africa. Traditional convective forecast tools (e.g. Total Totals Index, Lifted Index, K Index (KI) and Convective Available Potential Energy) do not accurately portray potential for thunderstorms in Africa. This research effort used the Gálvez-Davison Index (GDI), a convective index created for the tropics, and assess its applicability to northern Africa. GDI was produced for the Caribbean and Central America, and utilized temperature, moisture, mid-level stability, dry air entrainment and an elevation factor to calculate convective potential. In this research, GDI and KI were calculated using Global Forecast System (GFS) …

Forecasting Lightning Cessation Using Dual-Polarization Radar And Lightning Mapping Array Near Washington, D.C., Nancy M. Holden

Theses and Dissertations

Accurate forecasts of thunderstorms are important to space launch, aviation, and public safety. While prior studies have primarily focused on atmospheric conditions leading to lightning onset, less research has been dedicated to the challenging problem of predicting lightning cessation. This study verifies the probabilistic lightning cessation model developed by Joseph Patton (2017) at Florida State University for use by the U.S. Air Force's 45th Weather Squadron at Cape Canaveral Air Force Station (CCAFS) and the National Aeronautics and Space Administration (NASA) Kennedy Space Center (KSC). The Washington, D.C. greater metropolitan area, which presents a climate different to that of central …

Forecasting Sea Breeze Enhanced Thunderstorms At Eglin Air Force Base: A Comparison Between Empirical Methods And The High Resolution Rapid Refresh Model, Matthew P. King

Theses and Dissertations

Summer thunderstorms pose the greatest forecast challenge for the United States Air Force's 96th Weather Flight (96WF) which provides weather support for Eglin Air Force Base (AFB). Located on Florida's panhandle, Eglin AFB encompasses the Department of Defense's largest range complex which covers 134,000 sq mi (347,000 sq km) of water and 724 sq mi (1875 sq km) of land. Due to the base's coastal location and unique coastline geometry, sea breeze is a dominant forecast consideration for thunderstorms. The 96 WF currently utilizes an empirical method, called WINNDEX, developed by former staff meteorologist Roger Winn to aid in thunderstorm …

“Southerly Mohawk Hudson Convergence”- An Exploratory Case Study Of Terrain-Induced Wind Convergence On The Formation Of Thunderstorms In New York’S Capital Region, Christine Elizabeth Bloecker

Atmospheric & Environmental Sciences

Southerly Mohawk-Hudson Convergence (SMHC) is a mesoscale phenomenon over New York’s Capital Region whereby a southwesterly wind flow over Eastern New York is channeled by the mountainous terrain westerly through the Mohawk River Valley and southerly through the Hudson River Valley. When these winds converge over the Capital Region, thunderstorms may suddenly erupt, disrupting air and ground traffic in the area. On rare occasions, these storms may be severe. This is the first comprehensive study to be conducted on this phenomenon. Climatology was compiled and showed that SMHC occurs on average at least twice a year. A case study was …

Dynamical And Thermodynamic Processes Contributing To Thundersnow Events Over The Northeast U.S, Kyle Jacob Meier

Legacy Theses & Dissertations (2009 - 2024)

Thundersnow often occurs in conjunction with mesoscale snowbands and may be associated with regions of locally heavy snowfall (15-30 cm) and intense snowfall rates (5-10 cm/h). The availability of the National Lightning Detection Network (NLDN) system and operational Doppler weather radars during the past 20 years has allowed meteorologists to produce comprehensive national lightning maps and to identify localized areas of enhanced snowfall associated with thundersnow. The purpose of this thesis is to take advantage of the NLDN data and other contemporary observing systems in order to construct climatological, composite, and case study analyses of the atmospheric environment during thundersnow …

Numerical Investigation Of Orographic Effects On Supercell Thunderstorms, Galen M. Smith

Dissertations

Orographic effects on tornadic supercell development, propagation, and structure are investigated using the Cloud Model 1 with idealized bell-shaped mountains of various heights and geometries and a homogeneous fluid flow with a single sounding. In total, the variations of height and geometry yield 16 terrain configurations. It is found that blocking effects are dominative compared to the terrain-induced environmental heterogeneity downwind of the mountain. The isolated bell-shaped mountains tended to shift the track of the storm towards the left of storm motion; however, when the terrain was elongated the effect tended to be rightward. The terrain blocking effect also enhanced …

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 …

Leeside Boundary Layer Confluence And Afternoon Thunderstorms Over Mayaguez, Puerto Rico, Mark Jury, Sen Chiao

Faculty Publications, Meteorology and Climate Science

The midsummer boundary layer (BL) circulation and afternoon thunderstorm convection on the lee side of Puerto Rico is studied using observations and high-resolution models. Satellite infrared data help to identify cases on 5 and 14 June 2010 when midday surface temperatures show a 2°C gradient between land and sea and afternoon cloud-top temperatures <−60°C. Acoustic sounder profiles are analyzed for climatology, wind shear, turbulence, and diurnal cycles in the 40-300-m layer. Weather Research and Forecasting (WRF) model simulations indicate that sea-breeze flow is entrained into convective cells near Mayaguez, Puerto Rico. The simulated BL wind shear is too weak (0.5 × 10−2 s−1) in comparison with the acoustic sounder (2 × 10−2 s−1). Model 900-hPa winds are southeasterly and spread simulated convection too far north in comparison with radar. The pattern of near-surface winds in the island wake triggers afternoon thunderstorms near Mayaguez. A feature of the confluent circulation around Puerto Rico is opposing shear zones on the leeward corners of the island and a sea breeze of 5 m s−1 over the west coast during midday. [ABSTRACT FROM AUTHOR] . Copyright of Journal of Applied Meteorology & Climatology is the property of American Meteorological Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.).

The Educational Training Of Storm Chasers And Storm Spotters In Relation To Geographical Dispersion Across The United States, Paul R. Zunkel

All Graduate Theses, Dissertations, and Other Capstone Projects

When severe weather strikes, storm chasers and storm spotters confirm that what forecasters and meteorologists are seeing on a radar screen is actually occurring in the field. While some documenters are classically trained (i.e. they have a background in atmospheric science and or meteorology attained from a 4 year university) many others are not. There are currently two organizations available for the weather enthusiast to be a part of, SKYWARN and SpotterNetwork. These organizations give weather enthusiasts a background knowledge into severe weather; however, many weather enthusiasts are not classically trained and most have not taken any formal education in …

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 …

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 …

A Diagnostic Examination Of The Eastern Ontario And Western Quebec Wintertime Convection Event Of 28 January 2010, Shawn M. Milrad, John R. Gyakum, Eyad H. Atallah, Jennifer F. Smith

Publications

The priority of an operational forecast center is to issue watches, warnings, and advisories to notify the public about the inherent risks and dangers of a particular event. Occasionally, events occur that do not meet advisory or warning criteria, but still have a substantial impact on human life and property. Short-lived snow bursts are a prime example of such a phenomenon. While these events are typically characterized by small snow accumulations, they often cause very low visibilities and rapidly deteriorating road conditions, both of which are a major hazard to motorists. On the afternoon of 28 January 2010, two such …

Breaking Of Thunderstorm-Generated Gravity Waves As A Source Of Short-Period Ducted Waves At Mesopause Altitudes, Jonathan B. Snively, Victor P. Pasko

Publications

Numerical simulation results indicate that the breaking of atmospheric gravity waves generated by tropospheric convection can excite short-period secondary waves, which are trapped in the lower thermospheric duct and which closely resemble quasi-monochromatic structures commonly observed in airglow imaging experiments.

Experimental Goes Sounder Products For The Assessment Of Downburst Potential, Gary P. Ellrod, James P. Nelson Iii, Michael R. Witiw, Lynda Bottos, William P. Roeder

Aeronautics Faculty Publications

Several experimental products derived from Geostationary Operational Environmental Satellite (GOES) Sounder retrievals (vertical profiles of temperature and moisture) have been developed to assist weather forecasters in assessing the potential for convective downbursts. The product suite currently includes the wind index (WINDEX), a dry microburst index, and the maximum difference in equivalent potential temperature (θe) from the surface to 300 hPa. The products are displayed as color-coded boxes or numerical values, superimposed on GOES visible, infrared, or water vapor imagery, and are available hourly, day and night, via the Internet. After two full summers of evaluation, the products have been shown …

An Improved Thunderstorm Forecast Index For Cape Canaveral, Florida, James A. Everitt

Theses and Dissertations

This thesis creates a new algorithm to replace the Neumann-Pfeffer Thunderstorm Index (NPTI). The 45th Weather Squadron at Patrick AFB, Florida, uses the NPTI as an objective means of determining the probability of thunderstorm occurrence at Cape Canaveral. The probability is used for mission planning and resource protection, and increasing the accuracy of NPTI can potentially save billions of dollars for the United States space program. Stratified logistical regressions are performed and probability equations are derived for May through September using upper air data and surface observations for Cape Canaveral. A logistical regression of NPTI was also performed. Variables include …

Improving Cape Canaveral's Next-Day Thunderstorm Forecasting Using A Meso-Eta Model-Based Index, John C. Crane

Theses and Dissertations

Reliable thunderstorm forecasts are essential to safety and resource protection at Cape Canaveral. Current methods of forecasting day-2 thunderstorms provide little improvement over forecasting by persistence alone and are therefore in need of replacement. This research focused on using the mesoscale eta model to develop an index for improved forecasting of day-2 thunderstorms. Logistic regression techniques were used to regress the occurrence of a thunderstorm at Cape Canaveral against day-2 forecast variables output, or derived, from the mesoscale eta model. Accuracy and bias scores were calculated for the forecasts made by the regression equations, and the forecast results were compared …

Forecasting Wet Microbursts Associated With Summertime Airmass Thunderstorms Over The Southeastern United States, James B. Mackey

Theses and Dissertations

Microbursts are intense downbursts from thunderstorms that affect an area less than 4 km and have a lifespan less than 10 minutes. Wet microbursts are associated with heavy precipitation and are common in the eastern and southeastern part of the country. The greatest threat from microbursts is to low flying aircraft, where the rapid fluctuations in horizontal and vertical airflow create tremendous shear zones. Microbursts have been determined to be the causal factor behind at least three major aircraft accidents resulting in numerous fatalities. Due to the short lifespan of microbursts, they often strike without warning and pose a serious …

Improving Cape Canaveral's Day-2 Thunderstorm Forecasting Using Meso-Eta Numerical Model Output, Christian S. Wohlwend

Theses and Dissertations

The 45th Weather Squadron (WS) is responsible for the protection of billions of dollars worth of Air Force and NASA equipment from weather hazards. They produce a seven day planning forecast as one tool to support the space launch community. Improving this forecast can potentially save millions of dollars of government funds. This research focuses on the feasibility of improving the day two thunderstorm forecast by applying Meso Eta numerical forecasts to the Neumann-Pfeffer Thunderstorm Index (NPTI). The NPTI is currently used by the 45th WS for same day thunderstorm probability forecasting utilizing the morning radiosonde as input. The perfect …