+publisher:"University of Oklahoma" +contributor:("Biggerstaff, Michael")

University of Oklahoma

1. Dunn, Zachary. Digital Predistortion of Pseudo-Orthogonal Wideband Waveforms for Dual-Polarimetric Phased Array Radars.

Degree: PhD, 2016, University of Oklahoma

URL: http://hdl.handle.net/11244/34587

► Many new and interesting radar operational modes and techniques are being explored to maximize the efficiency and utility of next-generation radar systems while complying with… (more)

▼ Many new and interesting radar operational modes and techniques are being explored to maximize the efficiency and utility of next-generation radar systems while complying with increasingly stringent operational and budgeting requirements. This dissertation's aim is to analyze and present possible techniques to help maximize the scientific value of measurements while complying with operational requirements through methods of physical transmission and exciting the target area, methods of processing the received waveforms, and methods of designing waveforms for a given system. In regard to methods of physical transmission and exciting the target area, this dissertation addresses unique problems that will be faced by next-generation radar systems utilizing simultaneous transmit and simultaneous receive operational modes in polarimetric active phased array architectures. This is accomplished through establishing mathematical representations of the received complex baseband waveforms for dual-polarimetric radar operation and analyzing the predicted behavior versus traditional polarimetric radar alternating transmit and simultaneous receive operation. In regard to methods of processing the received waveforms, pulse compression will undoubtedly be widely utilized in future radar systems due to the increase in range resolution that it provides for a given pulse length. Additionally, matched filtering allows the realization of simultaneously transmitted pseudo-orthogonal waveforms occupying the same spectral region that would be otherwise impossible. As a result, the mathematical basis of pulse compression is provided, and pulse compression effects are taken into account in all relevant system analyses in this manuscript. This dissertation arguably provides the most attention in regard to methods for designing and modifying waveforms for application in a given system. An analysis of common pulse compression waveforms for suitability in pseudo-orthogonal waveform sets is provided in addition to a novel method for designing polyphase coded waveform and non-linear frequency modulated waveform based pseudo-orthogonal waveform sets utilizing particle swarm optimization. Additionally, for the first time, research is presented on the full design and application methods for digital predistortion of wideband solid state radar amplifiers. Digital predistortion methods and results are presented for both the impedance matched high power amplifier case and for the varying load impedance case that can be expected to be encountered in radar systems utilizing electronic beamsteering in active phased array architectures. Overall, this dissertation's aim is to provide relevant results from conducted research in the form of analysis and novel design methods that can be applied in both the design and operation of next-generation radar systems to maximize utility and scientific data quality while operating within given system and environmental specifications. Advisors/Committee Members: Yeary, Mark (advisor), Fulton, Caleb (committee member), Goodman, Nathan (committee member), Ruyle, Jessica (committee member), Biggerstaff, Michael (committee member).

Subjects/Keywords: Digital Predistortion; Phased Array; Polarimetric; Engineering, Electronics and Electrical.

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APA (6^th Edition):

Dunn, Z. (2016). Digital Predistortion of Pseudo-Orthogonal Wideband Waveforms for Dual-Polarimetric Phased Array Radars. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/34587

Chicago Manual of Style (16^th Edition):

Dunn, Zachary. “Digital Predistortion of Pseudo-Orthogonal Wideband Waveforms for Dual-Polarimetric Phased Array Radars.” 2016. Doctoral Dissertation, University of Oklahoma. Accessed January 18, 2021. http://hdl.handle.net/11244/34587.

MLA Handbook (7^th Edition):

Dunn, Zachary. “Digital Predistortion of Pseudo-Orthogonal Wideband Waveforms for Dual-Polarimetric Phased Array Radars.” 2016. Web. 18 Jan 2021.

Vancouver:

Dunn Z. Digital Predistortion of Pseudo-Orthogonal Wideband Waveforms for Dual-Polarimetric Phased Array Radars. [Internet] [Doctoral dissertation]. University of Oklahoma; 2016. [cited 2021 Jan 18]. Available from: http://hdl.handle.net/11244/34587.

Council of Science Editors:

Dunn Z. Digital Predistortion of Pseudo-Orthogonal Wideband Waveforms for Dual-Polarimetric Phased Array Radars. [Doctoral Dissertation]. University of Oklahoma; 2016. Available from: http://hdl.handle.net/11244/34587

University of Oklahoma

2. DiGangi, Elizabeth. Observations of Evolving Lightning, Microphysics, and Kinematics for a Supercell, a Multicell, and a Mesoscale Convective System.

Degree: PhD, 2019, University of Oklahoma

URL: http://hdl.handle.net/11244/317788

► The Deep Convective Clouds and Chemistry (DC3) field experiment collected data on a variety of storms to investigate the relationships between lightning and other storm… (more)

Subjects/Keywords: Lightning; Meteorology; Cloud Microphysics; Severe Weather

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APA (6^th Edition):

DiGangi, E. (2019). Observations of Evolving Lightning, Microphysics, and Kinematics for a Supercell, a Multicell, and a Mesoscale Convective System. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/317788

Chicago Manual of Style (16^th Edition):

DiGangi, Elizabeth. “Observations of Evolving Lightning, Microphysics, and Kinematics for a Supercell, a Multicell, and a Mesoscale Convective System.” 2019. Doctoral Dissertation, University of Oklahoma. Accessed January 18, 2021. http://hdl.handle.net/11244/317788.

MLA Handbook (7^th Edition):

DiGangi, Elizabeth. “Observations of Evolving Lightning, Microphysics, and Kinematics for a Supercell, a Multicell, and a Mesoscale Convective System.” 2019. Web. 18 Jan 2021.

Vancouver:

DiGangi E. Observations of Evolving Lightning, Microphysics, and Kinematics for a Supercell, a Multicell, and a Mesoscale Convective System. [Internet] [Doctoral dissertation]. University of Oklahoma; 2019. [cited 2021 Jan 18]. Available from: http://hdl.handle.net/11244/317788.

Council of Science Editors:

DiGangi E. Observations of Evolving Lightning, Microphysics, and Kinematics for a Supercell, a Multicell, and a Mesoscale Convective System. [Doctoral Dissertation]. University of Oklahoma; 2019. Available from: http://hdl.handle.net/11244/317788

University of Oklahoma

3. Silveira, Allison. Charge Structure and Lightning Patterns in a Simulated Mesoscale Convective System.

Degree: PhD, 2016, University of Oklahoma

URL: http://hdl.handle.net/11244/34071

► Observational analyses of electric field measurements and inferred charge structure within the stratiform region of a mesoscale convective system (MCS) repeatedly reveal quasi-steady, horizontal charge… (more)

▼ Observational analyses of electric field measurements and inferred charge structure within the stratiform region of a mesoscale convective system (MCS) repeatedly reveal quasi-steady, horizontal charge layers at and above the melting level. Previous studies have concluded charge advection can explain the uppermost layers as charged ice particles are ejected from the convective line into the weaker downdrafts of the transition zone. These layers have been observed to slope through and persist beyond the transition zone into the weak, broad mesoscale updrafts of the stratiform region. Likewise, significant electric fields are consistently measured in the layer below -10°C through the melting level, indicative of appreciable charge density, yet are apparently independent of the convective line. The contribution of several possible charge separation processes to the generation and maintenance of charge layers near the melting level are examined in this study. A high-resolution, three-dimensional model with full dynamics and two-moment microphysics was employed. The cloud microphysics were improved to include the prediction of liquid water fractions on graupel and snow to better parameterize the hypothetical charge separation mechanisms. Similar structure to the standard conceptual model of a leading-line, trailing stratiform MCS was exhibited in the model solutions with respect to observed kinematics, microphysics, and charge. In contrast with earlier two-dimensional modeling studies, charge advection did not account for any appreciable charge beyond the transition zone. However, through use of the new mixed-phase particle microphysical scheme, a charging mechanism associated with particle melting was found to be capable of simulating widespread, appreciable charge near the melting level of the stratiform region. Advisors/Committee Members: Straka, Jerry (advisor), Mansell, Edward (advisor), Biggerstaff, Michael (committee member), Leslie, Lance (committee member), Murphy, Sheena (committee member), Ziegler, Conrad (committee member).

Subjects/Keywords: Atmospheric Sciences.; Meteorology; Electrification; Numerical Modeling

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APA (6^th Edition):

Silveira, A. (2016). Charge Structure and Lightning Patterns in a Simulated Mesoscale Convective System. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/34071

Chicago Manual of Style (16^th Edition):

Silveira, Allison. “Charge Structure and Lightning Patterns in a Simulated Mesoscale Convective System.” 2016. Doctoral Dissertation, University of Oklahoma. Accessed January 18, 2021. http://hdl.handle.net/11244/34071.

MLA Handbook (7^th Edition):

Silveira, Allison. “Charge Structure and Lightning Patterns in a Simulated Mesoscale Convective System.” 2016. Web. 18 Jan 2021.

Vancouver:

Silveira A. Charge Structure and Lightning Patterns in a Simulated Mesoscale Convective System. [Internet] [Doctoral dissertation]. University of Oklahoma; 2016. [cited 2021 Jan 18]. Available from: http://hdl.handle.net/11244/34071.

Council of Science Editors:

Silveira A. Charge Structure and Lightning Patterns in a Simulated Mesoscale Convective System. [Doctoral Dissertation]. University of Oklahoma; 2016. Available from: http://hdl.handle.net/11244/34071

University of Oklahoma

4. Betten, Daniel. A LAGRANGIAN PERSPECTIVE OF MESOCYCLONES AND DOWNDRAFTS IN OBSERVED AND NUMERICALLY SIMULATED SUPERCELLS.

Degree: PhD, 2018, University of Oklahoma

URL: http://hdl.handle.net/11244/299851

► On 29 May 2004, a high-precipitation supercell thunderstorm developed in western Oklahoma and produced tornadoes during almost every distinct mesocyclone cycle over a six-hour period.… (more)

▼ On 29 May 2004, a high-precipitation supercell thunderstorm developed in western Oklahoma and produced tornadoes during almost every distinct mesocyclone cycle over a six-hour period. The storm was exceptional in its size, lightning activity, and the duration of the parent mesocyclone lifecycles. Fortunately, the TELEX field project was in position to collect one of the best storm-scale radar datasets for a tornadic supercell with respect to the length of record, temporal resolution, and spatial coverage. The primary goal of this study was to explore the storm-scale structure of the mesocyclones, downdrafts, and low-level boundaries as the storm passed near the city of Geary, OK. Due to a lack of available tools, the secondary goal of this study was to develop methods for elucidating Lagrangian flow behavior and highlighting the most influential flow characteristics. A trajectory mapping framework was explored and developed whereby three-dimensional trajectory behavior is mapped out in two-dimensional space, representing either a horizontal or vertical plane of reference. The framework proved adept at highlighting past or future behavior, such as prior horizontal location that reveals regions with common source regions or future attributes air parcels that eventually flow into the mesocyclone. An idealized numerical simulation was used to explore the methodology and to show the lack of sensitivity in the patterns to spatial and temporal data limitations associated with radar-based wind analyses. After applying the trajectory mapping framework to the radar analyses, it was found that the exceptionally large and deep mesocyclone was responsible for organizing the storm-scale downdrafts throughout its lifecycle. As the midlevel circulation grew stronger, easterly cyclonic flow opposed the environmental westerly momentum and setup a deep convergence zone associated with the rear-flank downdraft on the north side of the circulation. Near the surface, the outflow from the RFD surges was consistently demarked by secondary rear-flank gust fronts on the western and southern sides of the circulation. Throughout the lifecycle of the mesocyclone, there was a strong correlation between the vertical structure of the mesocyclone and the location of the occlusion downdraft. When the circulation strength decreased with height, air parcels descended near the axis of rotation. However, when the gradient was negligible or increasing with height, air parcels descended on the outside of the circulation and reinforced outflow from the RFD, eventually helping initiate the occlusion process. Finally, mesocyclone source regions were mapped out in time and space and suggested that air parcels over a shallow layer from the southern forward flank and inflow regions were reaching the mesocyclone during the mature stage of the circulation. Trajectory-based estimates of mesocyclone inflow depth and volume both increased with time as the circulation strengthened but then abruptly decreased as the inflow was cutoff by an eastward shift… Advisors/Committee Members: Biggerstaff, Michael (advisor), Apanasov, Boris (committee member), Homeyer, Cameron (committee member), Wang, Xuguang (committee member), Wicker, Louis (committee member), Ziegler, Conrad (committee member).

Subjects/Keywords: Supercell; Trajectories; Dynamics; Radar

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Betten, D. (2018). A LAGRANGIAN PERSPECTIVE OF MESOCYCLONES AND DOWNDRAFTS IN OBSERVED AND NUMERICALLY SIMULATED SUPERCELLS. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/299851

Chicago Manual of Style (16^th Edition):

Betten, Daniel. “A LAGRANGIAN PERSPECTIVE OF MESOCYCLONES AND DOWNDRAFTS IN OBSERVED AND NUMERICALLY SIMULATED SUPERCELLS.” 2018. Doctoral Dissertation, University of Oklahoma. Accessed January 18, 2021. http://hdl.handle.net/11244/299851.

MLA Handbook (7^th Edition):

Betten, Daniel. “A LAGRANGIAN PERSPECTIVE OF MESOCYCLONES AND DOWNDRAFTS IN OBSERVED AND NUMERICALLY SIMULATED SUPERCELLS.” 2018. Web. 18 Jan 2021.

Vancouver:

Betten D. A LAGRANGIAN PERSPECTIVE OF MESOCYCLONES AND DOWNDRAFTS IN OBSERVED AND NUMERICALLY SIMULATED SUPERCELLS. [Internet] [Doctoral dissertation]. University of Oklahoma; 2018. [cited 2021 Jan 18]. Available from: http://hdl.handle.net/11244/299851.

Council of Science Editors:

Betten D. A LAGRANGIAN PERSPECTIVE OF MESOCYCLONES AND DOWNDRAFTS IN OBSERVED AND NUMERICALLY SIMULATED SUPERCELLS. [Doctoral Dissertation]. University of Oklahoma; 2018. Available from: http://hdl.handle.net/11244/299851

University of Oklahoma

5. Buban, Michael. The formation of small-scale atmospheric vortices via horizontal shearing instability.

Degree: PhD, 2014, University of Oklahoma

URL: http://hdl.handle.net/11244/13870

► Motivated by recent high-resolution observations of small-scale atmospheric vortices along near-surface boundaries, this study presents a series of simulations that attempt to replicate the dynamics… (more)

▼ Motivated by recent high-resolution observations of small-scale atmospheric vortices along near-surface boundaries, this study presents a series of simulations that attempt to replicate the dynamics of the dryline and surrounding boundary layer with special emphasis on misocyclones. The first simulation was a real data case, initialized and forced through time-dependent lateral boundary conditions via analyses of temperature, moisture, and momentum from the 22 May 2002 IHOP dataset. The second series of simulations were barotropic runs, initialized with a north-south oriented constant vorticity shear zone and north-south periodic boundary conditions. The third series of simulations were baroclinic, where the shear zone also contained and east-west temperature gradient. The barotropic and baroclinic simulations had varying magnitudes of shear and shear zone widths (corresponding to differing initial vorticity values) across the runs. Additionally, several barotropic simulations were rerun with moisture included to assess preferred could formation regions. The real data simulation produced several misocyclones with characteristics consistent with those observed along near-surface boundaries in the atmosphere. Several of these misocyclones also had features resembling those observed in many laboratory studies and other numerical studies. Many of these features were also found in the barotropic simulations (i.e. instabilities developed into elliptical cores that precess, contain pressure perturbations in their centers, and evolve with cores connected by vorticity braids). To assess the instability mechanism, the results were compared to linear theory. Excellent agreement was found between predictions from linear theory in terms of wavenumber of maximum growth as a function of shear zone width and growth rate as a function of shear zone vorticity, suggesting to a very good first approximation, horizontal shearing instability (HSI) is responsible for the growth of initial small perturbations. It was also found that predictions of linear theory tend to extend well into the nonlinear regime. The baroclinic simulations were more complicated and allowed for tilting and stretching of vorticity not seen in the barotropic simulations. As the shear zones contract due to frontogenesis, vorticity increases, thus increasing the growth rates and the wavenumber of maximum growth. An attempt was made to model the contraction and apply a “modified linear theory” to the results, by allowing linear theory to have a time-varying shear zone width. This modified model provided excellent agreement with the simulated results in terms of growth rate and wavenumber of maximum growth. Finally, an attempt was made to assess preferred regions of cumulus formation by including moisture in the real data case and in several barotropic simulations. It was found that maximum updrafts and simulated cumuli tend to form along the periphery of cores and/or along the braided regions adjacent to the cores. Due to the important modulating… Advisors/Committee Members: Ziegler, Conrad (advisor), Biggerstaff, Michael (committee member), Shapiro, Alan (committee member), Fedorovich, Evgeni (committee member), Wicker, Louis (committee member), Lakshmivarahan, S. (committee member).

Subjects/Keywords: Physics, Atmospheric Science.; Physics, Fluid and Plasma.; Physics, General.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Buban, M. (2014). The formation of small-scale atmospheric vortices via horizontal shearing instability. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/13870

Chicago Manual of Style (16^th Edition):

Buban, Michael. “The formation of small-scale atmospheric vortices via horizontal shearing instability.” 2014. Doctoral Dissertation, University of Oklahoma. Accessed January 18, 2021. http://hdl.handle.net/11244/13870.

MLA Handbook (7^th Edition):

Buban, Michael. “The formation of small-scale atmospheric vortices via horizontal shearing instability.” 2014. Web. 18 Jan 2021.

Vancouver:

Buban M. The formation of small-scale atmospheric vortices via horizontal shearing instability. [Internet] [Doctoral dissertation]. University of Oklahoma; 2014. [cited 2021 Jan 18]. Available from: http://hdl.handle.net/11244/13870.

Council of Science Editors:

Buban M. The formation of small-scale atmospheric vortices via horizontal shearing instability. [Doctoral Dissertation]. University of Oklahoma; 2014. Available from: http://hdl.handle.net/11244/13870

University of Oklahoma

6. Flournoy, Matthew. Examining Environmental Conditions, Storm-scale Characteristics, and Tornado Potential in Observed and Simulated Supercell Thunderstorms.

Degree: PhD, 2020, University of Oklahoma

URL: http://hdl.handle.net/11244/325303

► Despite advancements in our understanding of supercell thunderstorms, numerous questions remain regarding relationships between their environment, storm-scale characteristics, and tornado potential. In particular, quantifying the… (more)

▼ Despite advancements in our understanding of supercell thunderstorms, numerous questions remain regarding relationships between their environment, storm-scale characteristics, and tornado potential. In particular, quantifying the range of storms possible in a given environment is an active area of research, and examining these relationships in time remains even more unexplored. This dissertation addresses these two research foci using a blend of numerical modelling and observational analysis. First, two 15-member ensembles of high-resolution, idealized simulations are con- ducted to explore the sensitivity of supercellular tornado production to small, storm-scale variations. The composite near- and far-field tornadic VORTEX2 profiles (Parker 2014) are used as the base-state for each of these two ensembles. Within each environment, the initial wind profile is perturbed slightly, resulting in 15 slightly different storms evolving within each environment. Based on my definition of a “tornado” in the simulation, all members in the near-field environment produce a tornado while only 40% of those in the far-field environment produce a tornado. Important storm-scale characteristics differ between the two ensembles, especially in terms of low-level updraft strength and surface outflow temperature. These results also show that storm-environment modifications can result in a local environment much more supportive of tornado potential. Next, an observational dataset consisting of 902 soundings and 220 supercell tracks is analyzed to better understand storm-track characteristics, particularly related to the right turn, and their relationship to environmental conditions. No significant correlations were found between the environmental parameters examined here and the time of the right turn. However, larger values of 0–1 km AGL streamwise horizontal vorticity magnitude tended to coincide with cells turning right within the first 65 minutes of their lifetime, and vice versa for smaller values of streamwise horizontal vorticity. The mean time between the cell’s first appearance on radar and the right turn was around 45 minutes for all supercells with a standard deviation of 25–30 minutes. Mean streamwise horizontal vorticity was significantly larger in the tornadic environments in the 0–1 and 0–3 km AGL layers, but not the 0–0.5 km AGL layer. Interestingly, mean crosswise horizontal vorticity was not significantly different between the tornadic and nontornadic subsets. A goal of this work was to identify relationships and/or processes linking environ- mental conditions to supercell characteristics that may be relevant to real-time forecasters, either immediately or in the near-future. Some conclusions from this work that are relevant to this goal include further quantifying what range of storms, in terms of tornado production, are possible in different environments and mean statistics regarding characteristics of the right turn in supercells. Future work will continue to use a blend of analysis methods to further examine… Advisors/Committee Members: Coniglio, Michael (advisor), Rasmussen, Erik (committee member), Silva, Carol (committee member), Homeyer, Cameron (committee member), Wang, Xuguang (committee member), Biggerstaff, Michael (committee member).

Subjects/Keywords: Meteorology; Atmospheric Sciences; Tornadoes; Supercells

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Flournoy, M. (2020). Examining Environmental Conditions, Storm-scale Characteristics, and Tornado Potential in Observed and Simulated Supercell Thunderstorms. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/325303

Chicago Manual of Style (16^th Edition):

Flournoy, Matthew. “Examining Environmental Conditions, Storm-scale Characteristics, and Tornado Potential in Observed and Simulated Supercell Thunderstorms.” 2020. Doctoral Dissertation, University of Oklahoma. Accessed January 18, 2021. http://hdl.handle.net/11244/325303.

MLA Handbook (7^th Edition):

Flournoy, Matthew. “Examining Environmental Conditions, Storm-scale Characteristics, and Tornado Potential in Observed and Simulated Supercell Thunderstorms.” 2020. Web. 18 Jan 2021.

Vancouver:

Flournoy M. Examining Environmental Conditions, Storm-scale Characteristics, and Tornado Potential in Observed and Simulated Supercell Thunderstorms. [Internet] [Doctoral dissertation]. University of Oklahoma; 2020. [cited 2021 Jan 18]. Available from: http://hdl.handle.net/11244/325303.

Council of Science Editors:

Flournoy M. Examining Environmental Conditions, Storm-scale Characteristics, and Tornado Potential in Observed and Simulated Supercell Thunderstorms. [Doctoral Dissertation]. University of Oklahoma; 2020. Available from: http://hdl.handle.net/11244/325303

University of Oklahoma

7. Bodine, David. Polarimetric Radar Observations and Numerical Simulations of Tornadic Debris.

Degree: PhD, 2014, University of Oklahoma

URL: http://hdl.handle.net/11244/10424

► Tornadic debris are critical aspects of tornado studies because airborne debris pose significant threats to life and property, and debris often dominate backscattered radar signals,… (more)

▼ Tornadic debris are critical aspects of tornado studies because airborne debris pose significant threats to life and property, and debris often dominate backscattered radar signals, causing biased Doppler velocity measurements. Polarimetric radar offers new research opportunities because debris produce a unique polarimetric radar signature called the tornadic debris signature (TDS). In this study, new applications of TDSs are examined using Transmission (T) matrix calculations, polarimetric radar observations, and numerical simulations. To illuminate electromagnetic scattering characteristics of different debris types, T-matrix calculations are presented. While most TDS studies have focused on tornado detection, this study conducts a detailed analysis of 14 TDS cases to determine relationships between TDS parameters and EF-rating. As tornado EF-rating increases, 90th percentile radar reflectivity factor, TDS height, and TDS volume increase, and 10th percentile co-polar cross-correlation coefficient and differential reflectivity decrease. While the TDS parameter analysis focuses on a single radar frequency, debris scattering characteristics vary depending on radar frequency, and thus multiple frequency polarimetric radar observations may provide new information about debris. In a statistical analysis of dual-wavelength TDSs, higher radar reflectivity factor and lower co-polar cross-correlation coefficient are observed at S band compared to C band, and negative differential reflectivity is sometimes observed simultaneously at both frequencies. Multiple frequency radar observations have additional utility in determining debris concentrations to assess debris loading impacts. To simulate polarimetric radar signatures, tornado vortices are simulated in a Large-Eddy Simulation (LES) model with a drag force coupling parameterization based on debris trajectories, enabling momentum exchange between air and debris. As debris loading increases, simulations reveal decreasing near-surface radial, tangential and vertical velocities in the lowest grid cell. Further increases in debris loading cause greater reductions in near-surface velocities and reduced tornado core tangential and vertical velocities. Using T-matrix calculations and LES model runs, equivalent radar reflectivity factor and two-way attenuation rates are calculated to determine if equivalent radar reflectivity factor or attenuation provide useful upper-bounds on debris loading. These simulations reveal that if sufficient amounts of debris loading are present to affect tornado dynamics, significant attenuation will occur at W band, in many cases fully attenuating the transmitted radar signal. Advisors/Committee Members: Palmer, Robert (advisor), Biggerstaff, Michael (committee member), Bluestein, Howard (committee member), Heinselman, Pamela (committee member), Yeary, Mark (committee member).

Subjects/Keywords: Atmospheric Sciences.

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APA (6^th Edition):

Bodine, D. (2014). Polarimetric Radar Observations and Numerical Simulations of Tornadic Debris. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/10424

Chicago Manual of Style (16^th Edition):

Bodine, David. “Polarimetric Radar Observations and Numerical Simulations of Tornadic Debris.” 2014. Doctoral Dissertation, University of Oklahoma. Accessed January 18, 2021. http://hdl.handle.net/11244/10424.

MLA Handbook (7^th Edition):

Bodine, David. “Polarimetric Radar Observations and Numerical Simulations of Tornadic Debris.” 2014. Web. 18 Jan 2021.

Vancouver:

Bodine D. Polarimetric Radar Observations and Numerical Simulations of Tornadic Debris. [Internet] [Doctoral dissertation]. University of Oklahoma; 2014. [cited 2021 Jan 18]. Available from: http://hdl.handle.net/11244/10424.

Council of Science Editors:

Bodine D. Polarimetric Radar Observations and Numerical Simulations of Tornadic Debris. [Doctoral Dissertation]. University of Oklahoma; 2014. Available from: http://hdl.handle.net/11244/10424

University of Oklahoma

8. Griffin, Erica. A Polarimetric and Microphysical Investigation of Winter Storms.

Degree: PhD, 2018, University of Oklahoma

URL: http://hdl.handle.net/11244/316762

► The U.S. WSR-88D network has been upgraded to polarimetric capabilities, providing dual-polarization data for regions of the country never before sampled by polarimetric radar and… (more)

▼ The U.S. WSR-88D network has been upgraded to polarimetric capabilities, providing dual-polarization data for regions of the country never before sampled by polarimetric radar and allowing for an unprecedented view into the ice microphysical processes within winter precipitation. As the polarimetric data became available, a database was compiled, consisting of thousands of hours of polarimetric observations in a wide variety of winter precipitation events and exhibiting several intriguing and repetitive polarimetric signatures. Understanding what these polarimetric signatures reveal about different microphysical processes is crucial for improving their representation in numerical weather prediction models and quantitative precipitation estimation algorithms, as well as for better understanding precipitation formation and evolution throughout the depth of a cloud, ultimately improving winter weather forecasting. This study first investigates the evolution and nature of intriguing and previously undocumented polarimetric signatures observed during the historic 8-9 February 2013 Northeast blizzard, and examines them in light of the thermodynamic environment within which they developed and the apparent microphysical processes that were active when they appeared. A more climatological and quantitative analysis is then conducted using a new quasi-vertical profile (QVP) methodology to investigate the microphysical evolution and significance of polarimetric signatures and their statistical correlations in the dendritic growth layer (DGL), at the tops of clouds, and near and within the melting layer (ML) in a selection of winter events. A statistical polarimetric model of the ML is introduced and a new method to estimate KDP in the ML is used to present the first reliable QVP statistics of KDP in the ML at S band. Advisors/Committee Members: Schuur, Terry (advisor), Chilson, Phillip (advisor), Biggerstaff, Michael (committee member), Zhang, Guifu (committee member), Engel, Michael (committee member).

Subjects/Keywords: Polarimetric radar; Ice microphysics; Winter storms; Quasi-Vertical Profiles

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APA (6^th Edition):

Griffin, E. (2018). A Polarimetric and Microphysical Investigation of Winter Storms. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/316762

Chicago Manual of Style (16^th Edition):

Griffin, Erica. “A Polarimetric and Microphysical Investigation of Winter Storms.” 2018. Doctoral Dissertation, University of Oklahoma. Accessed January 18, 2021. http://hdl.handle.net/11244/316762.

MLA Handbook (7^th Edition):

Griffin, Erica. “A Polarimetric and Microphysical Investigation of Winter Storms.” 2018. Web. 18 Jan 2021.

Vancouver:

Griffin E. A Polarimetric and Microphysical Investigation of Winter Storms. [Internet] [Doctoral dissertation]. University of Oklahoma; 2018. [cited 2021 Jan 18]. Available from: http://hdl.handle.net/11244/316762.

Council of Science Editors:

Griffin E. A Polarimetric and Microphysical Investigation of Winter Storms. [Doctoral Dissertation]. University of Oklahoma; 2018. Available from: http://hdl.handle.net/11244/316762

University of Oklahoma

9. May, Ryan Michael. Estimating and Mitigating Errors in Dual-Polarization Radar Attenuation Correction.

Degree: PhD, 2014, University of Oklahoma

URL: http://hdl.handle.net/11244/13621

► Correction for rain attenuation is an important data quality issue when using data collected by radars operating at attenuating wavelengths, specifically C and X bands.… (more)

Subjects/Keywords: polarimetric radar; dual-polarization; attenuation; simulation

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APA (6^th Edition):

May, R. M. (2014). Estimating and Mitigating Errors in Dual-Polarization Radar Attenuation Correction. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/13621

Chicago Manual of Style (16^th Edition):

May, Ryan Michael. “Estimating and Mitigating Errors in Dual-Polarization Radar Attenuation Correction.” 2014. Doctoral Dissertation, University of Oklahoma. Accessed January 18, 2021. http://hdl.handle.net/11244/13621.

MLA Handbook (7^th Edition):

May, Ryan Michael. “Estimating and Mitigating Errors in Dual-Polarization Radar Attenuation Correction.” 2014. Web. 18 Jan 2021.

Vancouver:

May RM. Estimating and Mitigating Errors in Dual-Polarization Radar Attenuation Correction. [Internet] [Doctoral dissertation]. University of Oklahoma; 2014. [cited 2021 Jan 18]. Available from: http://hdl.handle.net/11244/13621.

Council of Science Editors:

May RM. Estimating and Mitigating Errors in Dual-Polarization Radar Attenuation Correction. [Doctoral Dissertation]. University of Oklahoma; 2014. Available from: http://hdl.handle.net/11244/13621

10. Lu, Xu. Improving High-Resolution Tropical Cyclone Prediction using a Cycled, GSI-Based Hybrid Ensemble-Variational Data Assimilation System for HWRF with Vortex Scale Observations.

Degree: PhD, 2019, University of Oklahoma

URL: http://hdl.handle.net/11244/322825

► A Gridpoint Statistical Interpolation analysis system (GSI)-based, continuously cycled, dual-resolution hybrid ensemble-variational (EnVar) data assimilation (DA) system is developed for the Hurricane Weather Research and… (more)

▼ A Gridpoint Statistical Interpolation analysis system (GSI)-based, continuously cycled, dual-resolution hybrid ensemble-variational (EnVar) data assimilation (DA) system is developed for the Hurricane Weather Research and Forecasting (HWRF) Model. The newly developed DA system is then used in this dissertation to address a few scientific and technical challenges in assimilating the vortex-scale observations to improve the numerical prediction of TCs. In the dissertation, the newly developed DA system is described first. Then, the next part addresses how various data assimilation configurations impact the vortex scale observation assimilation and the subsequent prediction using the DA system. It is found that (1) dual-resolution EnVar DA improves the analyzed storm structure and short-term maximum wind speed (Vmax) and minimum sea level pressure (MSLP) forecasts compared to coarser, single-resolution EnVar DA, but track and radius of maximum wind (RMW) forecasts do not improve. (2) Additionally, applying vortex relocation (VR) and vortex modification (VM) on the control background before DA improves the analyzed storm, overall track, RMW, MSLP, and Vmax forecasts. Further applying VR on the ensemble background improves the analyzed storm and forecast biases for MSLP and Vmax. (3) Also, using four-dimensional (4D) EnVar to assimilate tail Doppler radar (TDR) data improves the analyzed storm and short-term MSLP and Vmax forecasts compared to three-dimensional (3D) EnVar although 4DEnVar slightly degrades the track forecast. (4) Finally, a diagnostic on why advanced DA can improve the TC intensity forecast for Edouard (2014) is provided. In the third part, using the further upgraded DA system, the deficiency of the numerical model physics was discussed. Although the DA produces realistic 3D analyses to initialize the model, persistent Vmax spin-down is found during the rapid intensification of hurricane Patricia (2015). Diagnostics reveal that the spin-down issue is likely attributed to the deficient HWRF model physics which are unable to maintain the realistic 3D structures from the DA analysis. The horizontal diffusion is too strong to maintain the realistically observed vertical oscillation of radial wind near the eyewall region. The vertical diffusion profile cannot produce a sufficiently strong secondary circulation connecting the realistically elevated upper-level outflow produced in the DA analysis. Further investigations with different model physics parameterizations demonstrate that spin-down can be alleviated by modifying model physics. In particular, a modified turbulent mixing parameterization scheme together with a reduced horizontal diffusion is found to significantly alleviate the spin-down issue and to improve the intensity forecast. Additional experiments show that the peak simulated intensity and rapid intensification (RI) rate can be further improved by increasing the model resolution. But the model resolution is not as important as model physics in the spin-down alleviation. The… Advisors/Committee Members: Wang, Xuguang (advisor), Vedula, Prakash (committee member), Biggerstaff, Michael (committee member), Sakaeda, Naoko (committee member), Wicker, Louis (committee member).

Subjects/Keywords: Data Assimilation; Hurricane; Vortex Scale Observations

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APA (6^th Edition):

Lu, X. (2019). Improving High-Resolution Tropical Cyclone Prediction using a Cycled, GSI-Based Hybrid Ensemble-Variational Data Assimilation System for HWRF with Vortex Scale Observations. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/322825

Chicago Manual of Style (16^th Edition):

Lu, Xu. “Improving High-Resolution Tropical Cyclone Prediction using a Cycled, GSI-Based Hybrid Ensemble-Variational Data Assimilation System for HWRF with Vortex Scale Observations.” 2019. Doctoral Dissertation, University of Oklahoma. Accessed January 18, 2021. http://hdl.handle.net/11244/322825.

MLA Handbook (7^th Edition):

Lu, Xu. “Improving High-Resolution Tropical Cyclone Prediction using a Cycled, GSI-Based Hybrid Ensemble-Variational Data Assimilation System for HWRF with Vortex Scale Observations.” 2019. Web. 18 Jan 2021.

Vancouver:

Lu X. Improving High-Resolution Tropical Cyclone Prediction using a Cycled, GSI-Based Hybrid Ensemble-Variational Data Assimilation System for HWRF with Vortex Scale Observations. [Internet] [Doctoral dissertation]. University of Oklahoma; 2019. [cited 2021 Jan 18]. Available from: http://hdl.handle.net/11244/322825.

Council of Science Editors:

Lu X. Improving High-Resolution Tropical Cyclone Prediction using a Cycled, GSI-Based Hybrid Ensemble-Variational Data Assimilation System for HWRF with Vortex Scale Observations. [Doctoral Dissertation]. University of Oklahoma; 2019. Available from: http://hdl.handle.net/11244/322825

11. Waugh, Sean. A BALLOON-BORNE PARTICLE SIZE, IMAGING, AND VELOCITY PROBE FOR IN SITU MICROPHYSICAL MEASUREMENTS.

Degree: PhD, 2016, University of Oklahoma

URL: http://hdl.handle.net/11244/45407

► A balloon-borne instrument known as the PArticle Size, Image, and Velocity (PASIV) probe has been developed at the National Severe Storms Laboratory to provide in… (more)

Subjects/Keywords: Meteorology; Microphysics; Disdrometer; Balloon-borne

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APA (6^th Edition):

Waugh, S. (2016). A BALLOON-BORNE PARTICLE SIZE, IMAGING, AND VELOCITY PROBE FOR IN SITU MICROPHYSICAL MEASUREMENTS. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/45407

Chicago Manual of Style (16^th Edition):

Waugh, Sean. “A BALLOON-BORNE PARTICLE SIZE, IMAGING, AND VELOCITY PROBE FOR IN SITU MICROPHYSICAL MEASUREMENTS.” 2016. Doctoral Dissertation, University of Oklahoma. Accessed January 18, 2021. http://hdl.handle.net/11244/45407.

MLA Handbook (7^th Edition):

Waugh, Sean. “A BALLOON-BORNE PARTICLE SIZE, IMAGING, AND VELOCITY PROBE FOR IN SITU MICROPHYSICAL MEASUREMENTS.” 2016. Web. 18 Jan 2021.

Vancouver:

Waugh S. A BALLOON-BORNE PARTICLE SIZE, IMAGING, AND VELOCITY PROBE FOR IN SITU MICROPHYSICAL MEASUREMENTS. [Internet] [Doctoral dissertation]. University of Oklahoma; 2016. [cited 2021 Jan 18]. Available from: http://hdl.handle.net/11244/45407.

Council of Science Editors:

Waugh S. A BALLOON-BORNE PARTICLE SIZE, IMAGING, AND VELOCITY PROBE FOR IN SITU MICROPHYSICAL MEASUREMENTS. [Doctoral Dissertation]. University of Oklahoma; 2016. Available from: http://hdl.handle.net/11244/45407

University of Oklahoma

12. Giangrande, Scott Edward. Investigation of polarimetric measurements of rainfall at close and distant ranges.

Degree: PhD, School of Meteorology, 2007, University of Oklahoma

URL: http://hdl.handle.net/11244/1290

► Whereas the existing literature overwhelmingly recommends polarimetric methods for weather radar applications, the majority of dual-polarization studies have been conducted on datasets collected at relatively… (more)

Subjects/Keywords: Polarimetry.; Rain and rainfall Measurement.; Radar meteorology.; Precipitation (Meteorology); Atmospheric Sciences.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Giangrande, S. E. (2007). Investigation of polarimetric measurements of rainfall at close and distant ranges. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/1290

Chicago Manual of Style (16^th Edition):

Giangrande, Scott Edward. “Investigation of polarimetric measurements of rainfall at close and distant ranges.” 2007. Doctoral Dissertation, University of Oklahoma. Accessed January 18, 2021. http://hdl.handle.net/11244/1290.

MLA Handbook (7^th Edition):

Giangrande, Scott Edward. “Investigation of polarimetric measurements of rainfall at close and distant ranges.” 2007. Web. 18 Jan 2021.

Vancouver:

Giangrande SE. Investigation of polarimetric measurements of rainfall at close and distant ranges. [Internet] [Doctoral dissertation]. University of Oklahoma; 2007. [cited 2021 Jan 18]. Available from: http://hdl.handle.net/11244/1290.

Council of Science Editors:

Giangrande SE. Investigation of polarimetric measurements of rainfall at close and distant ranges. [Doctoral Dissertation]. University of Oklahoma; 2007. Available from: http://hdl.handle.net/11244/1290

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