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Wallentine, Kari D. "Thunderstorm phobia in dogs." Thesis, Kansas State University, 2008. http://hdl.handle.net/2097/11975.
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Master of ScienceDepartment of Animal Sciences and Industry
Janice C. Swanson
Canine thunderstorm phobia is a common, frustrating, and complex problem that, due to the often severe nature of the clinical signs, can lead to canine relinquishment to shelters. Although a potentially treatable disorder, existing treatment options have several limitations and variable success rates. Three survey-based studies were conducted to increase the knowledge base for canine thunderstorm phobia. The first study distributed 1445 surveys through 16 Kansas veterinary clinics to determine the prevalence and characteristics of thunderstorm phobic dogs and assess differences between affected and non-affected dogs. Of 463 dogs surveyed, 240 were thunderstorm phobic as assessed by their owners. Severe weather warning systems may play a role in thunderstorm phobia. Thunderstorm phobic dogs were more fearful when exposed to tornado sirens, both during actual storms and siren testing, indicating a possible effect of classical conditioning. No differences were noted regarding sex, breed, pedigree, or neuter status. Most affected dogs preferred to be indoors remaining near their owners. The second study distributed 1600 surveys through eight Kansas animal shelters to determine the prevalence of relinquished dogs with thunderstorm phobia. Other reasons for relinquishment were also assessed. A fear of thunder was among the least common behavioral problems leading to relinquishment in dogs. Only a quarter of owners had visited a veterinarian for assistance with behavioral problems. The third study involved the administration of dog appeasing pheromone (DAP) in a double-blind, placebo-controlled, randomized clinical trial to assess its efficacy as a sole treatment for thunderstorm phobia. Data was collected from 60 dog owners using behavioral assessment questionnaires. In dogs given the placebo, six behaviors significantly improved, with another eleven showing a numerical trend toward improvement. However, in dogs given DAP, significant improvement was seen in three of these same behaviors. Consequently, these results do not indicate the potential use of DAP for reducing fearful behaviors associated with thunderstorm phobia when compared to negative controls. Information gained from these studies allows veterinarians and behavioral researchers to better understand the extent of this behavioral disorder and hopefully stimulates future research to find new and more effective ways to treat it.
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Wurman, Joshua Michael Aaron Ryder. "Forcing mechanisms of thunderstorm downdrafts." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/59043.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1991.Includes bibliographical references (p. 151-156).
by Joshua Michael Aaron Ryder Wurman.
Sc.D.
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McConville, Alastair Charles. "The physical simulation of thunderstorm downbursts." Thesis, University of Birmingham, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.736955.
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Nordin, Stensö Isak. "Predicting Tropical Thunderstorm Trajectories Using LSTM." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231613.
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Thunderstorms are both dangerous as well as important rain-bearing structures for large parts of the world. The prediction of thunderstorm trajectories is however difficult, especially in tropical regions. This is largely due to their smaller size and shorter lifespan. To overcome this issue, this thesis investigates how well a neural network composed of long short-term memory (LSTM) units can predict the trajectories of thunderstorms, based on several years of lightning strike data. The data is first clustered, and important features are extracted from it. These are used to predict the mean position of the thunderstorms using an LSTM network. A random search is then carried out to identify optimal parameters for the LSTM model. It is shown that the trajectories predicted by the LSTM are much closer to the true trajectories than what a linear model predicts. This is especially true for predictions of more than 1 hour. Scores commonly used to measure forecast accuracy are applied to compare the LSTM and linear model. It is found that the LSTM significantly improves forecast accuracy compared to the linear model.Åskväder är både farliga och livsviktiga bärare av vatten för stora delar av världen. Det är dock svårt att förutsäga åskcellernas banor, främst i tropiska områden. Detta beror till större delen på deras mindre storlek och kortare livslängd. Detta examensarbete undersöker hur väl ett neuralt nätverk, bestående av long short-term memory-lager (LSTM) kan förutsäga åskväders banor baserat på flera års blixtnedlslagsdata. Först klustras datan, och viktiga karaktärsdrag hämtas ut från den. Dessa används för att förutspå åskvädrens genomsnittliga position med hjälp av ett LSTMnätverk. En slumpmässig sökning genomförs sedan för att identifiera optimala parametrar för LSTM-modellen. Det fastslås att de banor som förutspås av LSTM-modellen är mycket närmare de sanna banorna, än de som förutspås av en linjär modell. Detta gäller i synnerhet för förutsägelser mer än 1 timme framåt. Värden som är vanliga för att bedöma prognosers träffsäkerhet beräknas för att jämföra LSTM-modellen och den linjära. Det visas att LSTM-modellen klart förbättrar förutsägelsernas träffsäkerhet jämfört med den linjära modellen.
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Barrett, Kevin M. Greene Donald Miller. "The county bias of severe thunderstorm warnings and severe thunderstorm weather reports for the Central Texas region." Waco, Tex. : Baylor University, 2008. http://hdl.handle.net/2104/5161.
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Shield, Stephen Shield. "Predictive Modeling of Thunderstorm-Related Power Outages." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu152951430854521.
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Hsieh, Huey-Hong. "Stochastic daily thunderstorm generation in southeast Arizona." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/280114.
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Thunderstorm rainfall in semi-arid areas has very high spatial and temporal variability. Knowledge of the spatial characteristics of thunderstorm rainfall is important for the increasing demands of distributed hydrological modeling. Rainfall data from the semiarid USDA-ARS Walnut Gulch Experimental Watershed (WGEW) were used to investigate the spatial characteristics of thunderstorm rainfall in southeast Arizona and to develop a daily thunderstorm rainfall generator. WGEW has a very dense rain-gage network (1 gage per 2 km²) and very comprehensive historical records (over 40 years). These data were used to identify the following physical characteristics of thunderstorm rainfall: the transition probabilities, thunderstorm cell size, orientation, maximum rainfall depth within a storm cell and storm center location. The following statistical characteristics were identified through an analysis of the WGEW data: the storm center locations on WGEW have a Poisson distribution, the maximum depth within a storm cell has a lognormal distribution, the shape of a storm cell is elliptical with an average major axis length to the minor axis length ratio of 1.55 and the orientation of a storm cell is primarily NW or NE. The storm coverage and the maximum rainfall depth within a storm cell have a linear relationship after a logarithmic transformation. Storm occurrences have higher frequencies during the last two weeks of July and the first two weeks of August than other wet periods (July ∼ September). The stochastic daily summer rainfall generator being developed based on the statistical characteristics above was tested by comparing the simulation results with long-term historical records of representative gages on WGEW.
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ZUZUL, JOSIP. "Characterization of thunderstorm downburst winds through CFD techniques." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1081542.
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The characteristic wind field of a certain region is mostly governed by the climatology of its larger scale area. In the case of mid-latitude regions (e.g. Europe), their climatology is determined by the extra-tropical cyclones at the larger synoptic scale. Atmospheric boundary layer (ABL) winds based on synoptic-scale structures are hence considered as the foundation for codes and standards used to assess the wind loading of structures and to design structures to prevent wind-related damage accordingly. In addition to the ABL winds, the mid-latitude regions are also prone to winds of a non-synoptic origin at the mesoscale level, with thunderstorm outflows or downbursts being the representative of such non-synoptic wind action. Since they are determined by a set of features that makes them fundamentally different from the ABL winds, downbursts can produce the corresponding wind action that is often fatal to low-rise and mid-rise structures. On these grounds, a comprehensive initiative to enable a better understanding of fundamental downburst flow features relevant for the structural loading was framed under the umbrella of the ERC THUNDERR Project. The present thesis, as the numerical modeling part of the THUNDERR Project framework, aims to address the physical characteristics of thunderstorm downbursts through the application of Computational Fluid Dynamics (CFD) technique. The focus of this work is placed on the CFD reconstruction of experimental tests of the reduced-scale thunderstorm downbursts carried out in the WindEEE Dome Research Institute (University of Western Ontario, Canada). Although they recreate the downburst flow field, the experimental analysis is restricted to the limited number of probe points. In that perspective, CFD allows expanding the analysis of experimental tests to the entire flow field, which can reveal phenomenological aspects that are either challenging or impossible to retrieve from experimental tests only. Two fundamental downburst scenarios were analyzed: (i) an isolated vertical downburst, and (ii) a downburst embedded inside the approaching ABL flow. For that purpose, three CFD approaches of a ranging complexity level were adopted. The unsteady Reynolds-Averaged Navier-Stokes (URANS), hybrid Scale-Adaptive Simulations (SAS), and Large-Eddy Simulations were used, and their overall reliability was examined. Theimplications of the WindEEE Dome specific geometrical features (i.e. bell-mouth inflow nozzle) on the downburst flow reconstruction by the facility were further discussed. The bulk of the thesis discusses the dominant flow features of the downburst with the particular emphasis on the dynamics of dominant vortex structures (i.e. primary vortex, secondary vortex, trailing ring vortices) and their spatio-temporal influence on the vertical profiles of radial velocity component. The non-dimensional flow characteristics of interest were evaluated such as the trajectory of the primary vortex and the spatial dependence of the velocity of primary vortex propagation. Analyses were further extended for the case of a joint downburst and ABL wind interaction to address the dynamics between two different wind fields, and the genesis of the worst condition in terms of the maximum radial velocity due to the ABL wind entrainment was discussed. The flow field was analyzed across various azimuth angles with respect to the ABL flow to report on the flow asymmetry, and general implications of such downburst configuration on spatio-temporal evolution of wind velocity profiles which can produce severe conditions for low-rise and mid-rise structures.
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BRUSCO, STEFANO. "Transient phenomena induced by thunderstorm outflows on slender structures." Doctoral thesis, Università degli studi di Genova, 2021. http://hdl.handle.net/11567/1051022.
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The climatology at mid-latitudes (for instance, Europe) is dominated by both extra-tropical depressions at the synoptic scale and by mesoscale thunderstorm outflows (also called downbursts). Thunderstorm outflows are non-stationary phenomena, complex and potentially devastating, which strongly differ from synoptic winds under many points of view (genesis, scale, duration above all). Consequently, the induced wind fields are highly different. Modern codes and guidelines are mainly based on the cyclonic model, because of the persistent lack of knowledge about thunderstorm outflows, in particular concerning full-scale measurements. On the other hand, severe wind damage is often induced by downbursts, especially concerning low- and medium- rise structures (e.g., cranes, small turbines, light poles, low-canopies).
The present PhD Thesis is collocated within the framework of the ERC THUNDERR Project. It investigates aspects connected with the aerodynamic loading of structures subjected to thunderstorm outflows, particularly focusing on the transient aerodynamics and transient aeroelasticity. This is firstly pursued through the definition of analytical formulations which, starting from compatible vertical wind fields, permit to evaluate the aerodynamic wind loading by using the strip and quasi-steady theory. The application of the procedures on selected slender test structures shows that a crucial role is played by thunderstorm-induced variations of the wind angle of attack, which may increase or reduce the structure response. The second part of the Thesis is devoted to an extensive experimental campaign carried out at the multiple-fan wind tunnel of the Tamkang University, Taipei, which is able to simulate unsteady flows. The sectional model of a sharp-edged square cylinder, equipped with 94 pressure taps, is investigated and numerous configurations of the flow parameters are considered in order to study the effects of acceleration on the aerodynamic loads and on the vortex-shedding from the body. The drag coefficients and the fluctuating cross-flow force coefficients connected with vortex shedding are found to be either comparable or definitely lower than their corresponding values for steady flows. Furthermore, discontinuities of the shedding frequency are present during the transients and their number and magnitude appear to be connected with the acceleration of the flow.
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Maggio, Christopher Ross. "Estimations of lightning charge transfers in New Mexico thunderstorms and applications to lightning energy, thunderstorm generator currents, and above-cloud transient currents /." Full text available from ProQuest UM Digital Dissertations, 2007. http://0-proquest.umi.com.umiss.lib.olemiss.edu/pqdweb?index=0&did=1609152051&SrchMode=1&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1245341216&clientId=22256.
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Berdeklis, Peter. "The ice crystal-graupel collision charging mechanism of thunderstorm electrification." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0007/NQ41402.pdf.
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Solomon, Robert. "A modeling study of thunderstorm electrification and lightning flash rate /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/10022.
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Knutsson, Lars. "Sprite observations over France in relation to their parent thunderstorm system." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-303775.
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As a part of the European research program CAL, sprite observations were carried out from the OMP observatory in the French Pyrenees during the summer 2003. Images of the sprites were taken by two remotely controlled CCD cameras. The 23 July was considered particularly interesting because we then had access to data concerning both cloud-to-ground and intracloud lightning activity. This day was therefore chosen as the object of the present study. A large thunderstorm with two convective cores, one to the north and the other to the south, developed over the South of France during the late afternoon, and about two hours after sunset, the first sprite was detected. During a little more than three hours, 13 sprites were observed, 7 over the northern system and 6 over the southern system. The images enabled us to determine the azimuth angle of each sprite from the OMP observatory. 12 of the 13 sprites could be associated to positive cloud-to-ground flashes, and by putting together the sprite directions and the locations of the associated flashes on the radar images, we managed to get a rough idea of the position of the sprites in the storm system, and also to estimate their vertical and horizontal extent. Satellite images were included at this point of the study, and it appeared clear that sprites tend to occur over the stratiform region of the storm system in the area with the coldest (highest) cloud tops. The associated positive flashes were also within or close to this portion of the storm. The sprite occurrences were studied in relation to the cloud-to-ground and to the intracloud activity. We found that sprites seem to occur in a late stage of each storm system, when the rate of negative cloud-to-ground flashes has considerably decreased, and when the ratio of positive cloud-to-ground flashes is much higher then during the most active phase of the storm. Globally, the intracloud activity is also low during the sprite-producing periods, but sudden "bursts" of intracloud lightning could frequently be observed at the moment of the sprite. The peak current of the positive flashes was found to be rather weakly correlated to their sprite-generating capacity. The available Schumann resonance measurements seem to indicate that the charge moment is a much more adequate parameter in this respect. The areal coverage of the radar echo was calculated. The result supports the idea that sprite events tend to appear almost exclusively over large thunderstorm systems.
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Metzger, Eric L. "The relationship between total cloud lightning behavior and radar derived thunderstorm structure." Thesis, Monterey, California : Naval Postgraduate School, 2010. http://edocs.nps.edu/npspubs/scholarly/theses/2010/Mar/10Mar%5FMetzger.pdf.
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Thesis (M.S. in Meteorology)--Naval Postgraduate School, March 2010.Thesis Advisor: Nuss, Wendell. Second Reader: Pfeiffer, Karl. "March 2010." Author(s) subject terms: Total cloud lightning, thunderstorm structure, hail, severe wind(s), tornadoes, lightning jumps, lightning detection, Lightning behavior, radar derived thunderstorm structure. Includes bibliographical references (p. 83-85). Also available in print.
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Steiger, Scott Michael. "Thunderstorm lightning and radar characteristics: insights on electrification and severe weather forecasting." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4684.
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Total lightning mapping, along with radar and NLDN cloud-to-ground lightning
data, can be used to diagnose the severity of a storm. Analysis of the 13 October 2001
supercell event (Dallas-Fort Worth, Texas), some supercells of which were tornadic,
shows that LDAR II lightning source heights (quartile, median, and 95th percentile
heights) increased as the storms intensified. Most of the total lightning occurred where
reflectivity cores extended upwards and within regions of reflectivity gradient rather
than in reflectivity cores. A total lightning hole was associated with an intense, nontornadic
supercell on 6 April 2003. This feature was nonexistent from all supercells
analyzed during the 13 October case.
During tornadogenesis, the radar and LDAR II data indicated updraft weakening.
The height of the 30 dBZ radar top began to descend approximately 10 minutes (2
volume scans) before tornado touchdown in one storm. Total lightning and CG flash
rates decreased by up to a factor of 5 to a minimum during an F2 tornado touchdown
associated with this storm. LDAR II source heights all showed descent by 2-4 km during a 25 minute period prior to and during this tornado touchdown. This drastic trend
of decreasing source heights was observed in two tornadic storms prior to and during
tornado touchdown, but did not occur in non-tornadic supercells, suggesting that these
parameters can be useful to forecasters. These observations agree with tornadogenesis
theory that an updraft weakens and the mesocyclone can become divided (composed of
both updraft and downdraft) when a storm becomes tornadic.
LDAR II source density contours were comma-shaped in association with severe
wind events within mesoscale convective systems (MCSs) on 13 October 2001 and 27
May 2002. This signature is similar to the radar reflectivity bow echo. Consistent
relationships between severe weather, radar and lightning storm characteristics (i.e.,
lightning heights) were not found for cells within MCSs as was the case for supercells.
Cell interactions within MCSs are believed to weaken these relationships as reflectivity
and lightning from nearby storms contaminate the cells of interest. It is also more
difficult to clearly define a cell within an MCS.
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Boyer, D. G., and K. J. DeCook. "The Effect of an Intensive Summer Thunderstorm on a Semiarid Urbanized Watershed." Water Resources Research Center. The University of Arizona, 2014. http://hdl.handle.net/10150/314471.
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No date on item; authors' manuscript.The University of Arizona Atterbury Experimental Watershed, located southeast of Tucson, Arizona has been instrumented for precipitation and runoff measurements since 1956. Early on the afternoon of July 16, 1975 an intense convective thunderstorm produced more than three inches of rainfall in less than 50 minutes as recorded in several rain gages located in the middle of one 8.1 square-mile desert subwatershed. Storm runoff from this rural subwatershed and an adjacent recently urbanized subwatershed filled the newly finished Lakeside Reservoir and topped the concrete flood spillway with a peak of greater than 3000 cfs, the greatest flow since monitoring began. An analysis of storm characteristics, along with previously available data from local urbanized watersheds, allows speculation on the effect of such an intensive storm in a highly urbanized.area.
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ZHANG, SHI. "Characteristics, weather scenario and statistics of thunderstorm outflows based on measured data." Doctoral thesis, Università degli studi di Genova, 2020. http://hdl.handle.net/11567/1011313.
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Wind is the most destructive natural phenomenon: 70% of damage and death caused by nature in the world comes from wind. And extreme winds such as typhoons, tornadoes and thunderstorms are crucial for structural damage. Inside, during a thunderstorm, the transient downdraft that impinges on the ground produces radial outflows that can produce strong transient wind, which is the main cause of the collapse of tall structures such as transmission tower, besides one of the threat to human life and property security, for instance, the accident of transmission line towers in Ontario, Canada in August 2006 and "Oriental star" sinking in China in June, 2015 and so on. The study of thunderstorm outflows and their loading and response of structures already become a key topic in modern wind engineering. Despite this, the understanding, the representation and the modeling of thunderstorm outflows are still full of uncertainties and problems to be clarified. This happens because the complexity of the thunderstorm outflows makes it difficult to establish physically realistic and simple engineering schemes, their short duration and small size means few data are available, and a large gap exists between wind engineering and atmospheric science. It follows that the wind loading of structures is still evaluated by the Davenport’s model for extra-tropical cyclones without any concern for the real nature and the properties of the meteorological event that causes the loading. This is nonsense because extra-tropical cyclones and thunderstorm outflows are different phenomena that need separate assessments.
To overcome these limits, this PhD thesis carries out a deep research mainly on the characteristics of thunderstorm outflow according to wind field measurement and meteorological data based on a thunderstorm catalogue created extracted from a mixed climate, which mainly contains the proposal of more reasonable directional decomposed approach of thunderstorm outflow signal, the properties of thunderstorm related to wind loading on structures, the comprehensive analysis of field measurements and weather scenarios related to thunderstorms, the extreme wind speed distribution in a mixed wind climate and the preliminary study of the crucial question if thunderstorms in different areas have similar properties. The major contents and achievements are summarized as follows:
Firstly, measurements for up to 6 years related to 14 high-sampling rate anemometers of the monitoring network in the Northern Mediterranean ports are analyzed. Three intense phenomena, namely extra-tropical cyclones, thunderstorm outflow, and intermediate events are separated successfully by a semi-automatic procedure. The results lead to a wide dataset of 277 wind velocity records characterized by strong transient properties and labeled by thunderstorm outflow, which are catalogued into three families, named 10 minutes, 1 hour and 10 hours, according to the different time-scale of the gust front passage, and fundamental for the subsequent study.
Analyses are then executed to extract the parameters of major interest for evaluating the wind loading effects of structures. And a novel directional decomposition strategy is formulated here, which makes it possible to analyse quantitatively the directional shift of thunderstorm outflows, makes the study of thunderstorm outflows and synoptic winds fully coherent and is strategic to perform directional analyses of the dynamic behaviour of structures in terms of alongwind and crosswind response. Then this strategy is applied to thunderstorm records comparing with the classical decomposition approach and furnishing a comprehensive statistical characterization.
While the general analysis in wind engineering has a shortcoming that it misses the knowledge of the weather scenarios that occur during events classified as thunderstorms, without recognizing their actual meteorological nature. In order to take the first step towards filling this gap, a typical thunderstorm downburst and three events, each one representative of the corresponding class of duration, detected by our network are investigated from the meteorological point of view to represent a first step and a pilot attempt in this direction. The results obtained bring new insights into a thunderstorm’s onset and detection in the Mediterranean, its evolution at the local scale, and possible connections to specific synoptic-scale weather conditions.
Design wind speeds based on the statistical analysis of conventional extreme mean wind speed data in a mixed wind climate may prove to be imprecise and unsafe due to the occurrence of intense, small and rapid extreme wind events such as thunderstorm outflows. Considering the continuous records registered in two Port areas of the monitoring network, a preliminary but representative analysis of the extreme wind speed distribution is carried out in this mixed wind climate area frequently struck by thunderstorms. Results show that wind speeds with high return period are always related to thunderstorm outflows. It proves that gathering the ensemble of all extreme values into a single set and the analyses of the local wind climate ignoring thunderstorms may lead to underestimating the extreme wind speed.
At the end of the research, this analysis procedure is applied to the 5-year data from the 9 anemometers installed at different heights on Beijing 325m high meteorological tower to study the characteristics of thunderstorms in the Beijing urban area, to compare these with northern Mediterranean ones and to understand if thunder-storms in different areas have similar properties. In addition, the property of the mean wind speed profile and coherent function of thunderstorms are described, which provides a reference for the simulation of thunderstorm signal.
Hope this thesis could make some contributions to step further research on thunderstorm-resistant design for building structures.
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Motley, Shane Michael. "Total lightning characteristics of ordinary convection." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1735.
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Schroeder, Vicki. "How does lightning initiate and what controls lightning frequency? /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/6832.
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Davenport, Robert T. "Potential vorticity analysis of low level thunderstorm dynamics in an idealized supercell simulation." Thesis, Monterey, Calif. : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Mar/09Mar%5FDavenport.pdf.
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Thesis (M.S. in Meteorology)--Naval Postgraduate School, March 2009.Thesis Advisor(s): Nuss, Wendell A. "March 2009." Description based on title screen as viewed on April 23, 2009. Author(s) subject terms: Potential Vorticity, Severe Weather, Supercell, Weather Research and Forecasting Model, Advanced WRF. Includes bibliographical references (p. 43-47). Also available in print.
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Weygandt, Stephen Scott. "The retreival of initial forecast fields from single Doppler observations of a supercell thunderstorm /." Full-text version available from OU Domain via ProQuest Digital Dissertations, 1998.
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Miller, Paul Wesley. "The Utility of Total Lightning in Diagnosing Single-cell Thunderstorm Severity in the Central Appalachian Mountains Region." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/56976.
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Recent severe weather research has examined the potential role of total lightning patterns in the severe thunderstorm warning-decision process although none to-date have examined these patterns in explicitly weak-shear environments. Total lightning flashes detected by the Earth Networks Total Lightning Network (ENTLN) during the 2012-13 convective seasons (1 May – 31 August) over a region of the Central Appalachian Mountains were clustered into likely discrete thunderstorms and subsequently classified as either single-cell or multicell/supercell storm modes. The classification of storms was determined using a storm index (SI) which was informed by current National Weather Service (NWS) identification techniques. The 36 days meeting the minimum threshold of lightning activity were divided into 24 lightning-defined (LD) single-cell thunderstorm days and 12 LD multicell/supercell days. LD single-cell days possessed statistically significant lower 0000 UTC 0-6 km wind shear (13.8 knots) than LD multicell/supercell days (26.5 knots) consistent with traditional expectations of single-cell and multicell/supercell environments respectively.
The popular 2σ total lightning jump algorithm was applied to all flashes associated with 470 individual LD thunderstorms. The frequencies of the storms’ total lightning jumps were then compared against any associated severe weather reports as an accuracy assessment. The overall performance of the algorithm among both categories was much poorer than in previous studies. While probability of detections (POD) of the 2σ algorithm were comparable to previous research, false alarm rates (FAR) were much greater than previously documented. Given these results, the 2σ algorithm does not appear fit for operational use in a weak shear environment.Master of Science
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Emelie, Wennerdahl. "Change in Thunderstorm Activity in a Projected Warmer Future Climate: a Study over Europe." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-337148.
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In the last 100 years, a rise in the global mean temperature has been noted, and projections show even higher temperatures in the future. The temperature rise can lead to changes in the weather patterns and therefore the thunderstorm activity in a future warmer climate has been investigated in this study. The future projections were made with an ensemble of 8 General Circulation Models downscaled with the regional climate model RCA4, developed at SMHI. Temperature and humidity data at four different levels in the atmosphere has been used to compute three different stability indices. Stability indices indicate potential for deep convection in the atmosphere, from which thunderstorms are developed. It was found that the projections show an increase in thunderstorm potential in a warmer future climate. In Sweden, the projections show an increase with about 15 more days with risk of thunderstorms at the end of the 21st century for the RCP4.5 scenario, corresponding to an increase of 40% in the south, and an even larger increase in the north. For the RCP 8.5 scenario, the projected change in days with risk of thunderstorms corresponds to an increase about 20 days, or about 60% more thunderstorm days in south of Sweden. In other parts of Europe, the increase is expected to be even larger, mainly in the mountain regions. It was also found that the thunderstorm season is projected to be extended in the future, with more days with risk of thunder in May and September. The increase in number of days with risk of thunderstorms is a result of the greater amount of water vapour that the atmosphere is able to hold in a warmer climate. Even if thunderstorms are projected to increase, other factors counteract, such as a decrease in the vertical temperature gradient and a decrease in the difference between moisture in the upper and the middle atmosphere. Yet, taken together the days with risk of thunderstorms are projected to become more frequent.Under de senaste hundra åren har medeltemperaturen på jorden ökat med cirka 1°C, vilket har medfört förändringar i klimatet. Temperaturen kommer att fortsätta stiga på grund av den redan förhöjda halten växthusgaser i atmosfären, och om växthusgaser fortsätter släppas ut kan det förväntas bli ännu varmare. I och med att temperaturen fortsätter stiga är det mycket som pekar på att vädret i allmänhet kommer förändras, som till exempel förändrat mönster i åskoväder. I denna studie har risken för åska i ett framtida klimat studerats. Åska och konvektion bildas framförallt på grund av tre komponenter: instabilitet i atmosfären, fuktigheten i luften och en mekanism som får luften att lyftas från marken. En instabil luftmassa fås framförallt en varm sommardag när solen värmer marken, vilket medför att luften vid marken blir betydligt varmare än luften ovanför. Den andra faktorn är beroende av fuktigheten i luften, om luften är tillräckligt fuktig finns risk att större åskmoln kan bildas. De första två faktorerna kan beskrivas med vad som kallas stabilitetsindex. I denna studie beräknades risken för djup konvektion med hjälp utav stabilitetsindex. Temperatur-och fuktighetsdata från den regionala klimatmodellen RCA4, framställd på SMHI, användes för att beräkna dessa stabilitetsindex. Studien visar på att dagar med risk för åska förväntas öka i slutet av detta seklet med omkring 10-15 dagar per år över Sverige, med ännu fler dagar med risk för åska i södra Europa. En förhöjd åskrisk kan även förväntas vid bergskedjor så som svenska fjällen och Alperna. Den främsta anledningen till att åska förväntas bli vanligare är till följd av att temperaturstigningen möjliggör högre halt vattenånga i atmosfären, och därmed kommer fuktigheten i luften att öka. En längre åsksäsong har även noteras, med tidigare start i maj, och även förlängd i september.
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Sandifer, John B. "Meteorological measurements with a MWR-05XP phased array radar." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Mar%5FSandifer.pdf.
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Bahadoran, Baghbadorani Afsoon. "VR Based Aviation Training Application for Avoiding Severe Thunderstorms." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1627514676123053.
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Rosander, Christian. "Characteristics of convective cloud cluster formationover Thailand through satellite image analysis." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-303916.
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Weather forecasting relies on the availability of observational data as input parameters. However,such data are not readily available, because of difficulties to collect weather data due toinaccessibility to many places in the world, such as oceans or mountain regions. For this reason,satellite surveillance is a suitable tool to observe the atmosphere in regions where it is notpossible by other means. This master thesis is a study of convective cloud cluster formation over Thailand, conductedthrough satellite image analysis. Characteristics of cloud cluster formations are investigatedthrough an implementation of the Maximum Spatial Correlation Technique (MASCOTTE),described by Carvalho and Jones (2001). This method allows tracking of convective cloud systemsthrough region based analysis of satellite images. The aim of this study is to investigate whether satellite image analysis, through the implementationof the MASCOTTE methodology, can provide characteristics of convective cloud systems,in order to discern convective systems by intensity, accurately enough to be able to discernsevere thunderstorms from ordinary thunderstorms. The annual distribution of the occurrenceof life cycles detected through the analysis is studied, as well as their monthly distribution ofmean and maximum life times. Moreover, the yearly distribution of life cycle mean and minimumbrightness temperatures are analysed, as well as the number of detected split and mergeevents. This is followed by a comparison of life cycle structural properties to investigate thepossibility to use individual parameters, alone or in combination with each other, as indicatorsof the degree of convective activity within life cycles. Yearly distributions were studied in order to verify if this method could reveal seasonal variations,such as the onset period of the wet season, in terms of the occurrence of life cycles andtheir life time. The findings of this study verified that the most convectively intense life cycles exist under theinfluence of the Inter Tropical Convergence Zone (ITCZ), during the onset and beginning ofthe monsoon season. Analysis of life cycle structural properties, showed that properties likemean and minimum brightness temperature as well as fractional convective area, could be usedas indicators to discern between life cycles with different level of convective activity. However,it is concluded that studies, including ground-based remote sensing technologies such asRADAR/LIDAR, as well as data from rawinsondes, needs to be conducted in order to clarifyif it is possible to use this methodology to successfully discern severe thunderstorms fromordinary thunderstorms.Tillgängligheten av meteorologiska mätdata är väsentlig för att kunna prognostisera väder. Idag är tillgängligheten på dessa data relativt gles, bland annat på grund av svårigheter att mäta på många platser runt om i världen, t.ex över världshaven eller vid otillgängliga bergsområden. Därför är satellitövervakning ett bra alternativ till andra typer av väderobservationer, eftersom denna teknik kan tillhandahålla mätdata över stora områden som annars inte är möljiga att samla data från. Denna magisteruppsats är en studie om egenskaper hos konvektiv molnbildning över Thailand. Studien är genomförd med hjälp av satellitbildsanalys. Egenskaper hos olika konvektiva molnceller har studerats genom att använda en metod baserad på ”the Maximum Spatial Correlation Technique” (MASCOTTE), beskriven av Carvalho and Jones (2001). Tanken bakom denna metod är att hitta och följa utvecklingen av olika konvektiva molnceller baserat på deras storlek och temperatur. Målet med studien är att undersöka hurvida denna metoden kan ge kunskap som leder till att man kan skilja på konvektiva celler, genom intensitetsskillnader, med tillräcklig noggrannhet för att kunna urskilja vanliga konvektiva celler från intensiva celler. För att få en uppfattning om förekomsten av intensiva konvektiva system, har antalet detekterade livscykler per månad studerats. För sedan att få en bild av hurvida deras livscykler skiljer sig åt över året, har även egenskaper som medellivslängd och maximal livslängd studerats. Dessutom studerades den årliga fördelningen av livscyklernas medel och minimum temperaturer, samt förekomsten av delningar och sammanslagningar av konvektiva celler. För att finna kunskap om skillnader i intensitet mellan individuella livscykler, har egenskaper som medel och minimum temperatur analyserats. Dessutom har andelen moln med extremt låg temperatur studerats i syfte att kunna använda dessa parametrar som intensitetsindikatorer vid satellitbildsanalys. Resultaten i denna studie visar att de mest intensiva konvektiva molnsystemen (kraftigaste åskvädren), förekommer under påverkan av ITCZ (Inter Tropical Convergence Zone), under antågandet och början av regnperioden. Studier av de konvektiva systemens egenskaper visade att parametrar, som andelen extremt kallt område i molnceller (fractional convective area), och livscyklernas medel och minimum temperaturer, skulle kunna användas som intensitetsindikatorer för att skilja på olika livscykler med avseende på deras styrka i intensitet. Slutsatsen av studien är att det behövs fler studier där andra typer av meteorologiska mätdata, såsom RADAR/LIDAR och sonderingsdata är involverade, för att skaffa ytterligare kunskap om hur man genom satellitbildsanalys kan urskilja kraftiga åskväder.
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White, Trevor Stewart. "Dual-Doppler Derived Vorticity as a Predictor of Hail Size in Severe Thunderstorms." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/74927.
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One of the primary missions of the National Weather Service (NWS) is to use a network of more than 150 NEXRAD radar installations to monitor weather for threats to life and property. Large hail produced by severe thunderstorms is a major focus of this mission. An algorithm known as the Maximum Estimated Size of Hail (MESH) algorithm is in operational use to diagnose the presence and size of hail. This study aims to use dual-Doppler observations as well as the MESH algorithm to test the idea that storms that rotate produce larger hail. Previous studies have used polarimetric radar products to detect the presence of large hail and dual-Doppler methods have been used to study embryonic hail, but no research has tested the theory of hail and rotating storms with observational evidence. A set of 59 case studies was gathered; each included a hail report submitted by a trained weather spotter or NWS employee and complete radar observations through the depth of a storm from two radars. The radar observations were resampled to a three-dimensional Cartesian grid and a dual-Doppler analysis was run on each case study. A strong correlation (stronger even than the MESH algorithm) was found between measured vorticity and hail size, lending credence to the idea that rotating storms do indeed have a higher ceiling for hail production. However, no correlation was found between MESH error and rotation. Further research will be required to evaluate whether or not this relationship can be used to augment the MESH algorithm so as to improve its skill.Master of Science
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Faidley, Galen William. "The Virtual Storm an exploratory virtual environment of a supercell tornadic thunderstorm for meteorological education /." [Ames, Iowa : Iowa State University], 2006.
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Hitchens, Nathan M. "The possible relationships between atmospheric teleconnections and severe thunderstorm outbreaks in the continental United States." Virtual Press, 2006. http://liblink.bsu.edu/uhtbin/catkey/1339150.
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The purpose of this study is to examine possible relationships between changes in values of teleconnection indices related to the Southern Oscillation Index (SOI), North Atlantic Oscillation (NAO), Pacific-North American (PNA) pattern, and Arctic Oscillation (AO), and outbreaks of severe thunderstorms for specific time periods following such changes. A series of chi-squared tests are performed to determine if statistically significant relationships exist between changes in teleconnection index values and the occurrence of severe thunderstorm outbreaks. Results indicate that changes in the SOI seem to be related to an increase in the frequency of outbreaks that follow in the short-term.Department of Geography
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Thiel, Kevin C. Thiel. "Relating Multi-Radar/Multi-Sensor (MRMS) and Dual-Polarization Products to Lightning and Thunderstorm Severity Potential." Ohio University Art and Sciences Honors Theses / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ouashonors1524746999247939.
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Waddicor, David Alan. "Aerosol in the tropical tropopause layer." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/aerosol-in-the-tropical-tropopause-layer(c68a4252-15dc-4a96-a890-0156719b3a9f).html.
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This thesis details the ACTIVE campaign in the tropics of northern Australia during 2005-2006 (based in Darwin). The focus of the campaign was to find the influence of tropical convection on the aerosol and chemical content of the Tropical Tropopause Layer [TTL] and the cirrus cloud cover in the area, which is important for the global energy budget. This study details the background climatology of the Darwin region with statistical categorisation of the trace gases and particles. The TTL had regions of extremely high aerosol number concentration, much higher than that of the PBL. The 10 to 1000 nm particle concentrations were as high as 25,000 cm-3 and 100 to 1000 nm were as high as 1000 cm-3. High aerosol concentrations were usually found in cloud-free conditions; cloudy regions were typically low in aerosol number. Wind data and trajectories (BADC) were used to find the origin of the high particle concentrations. Aerosols were found to be nucleating in outflow regions of convective anvils. SO2 oxidation to H2SO4 is a widely accepted mechanism for nucleation. A binary mechanism (H2O-H2SO4), with SO2 as the precursor, was found to be inadequate in explaining the nucleation and growth rates -- tested using an aerosol sectional model. However, it was found, via back trajectory analysis, that the climatology of Darwin was influenced by local and long-range sources, including advection from Indonesia and the Tropical Warm Pool. These distant sources could have introduced condensable matter, with aerosol precursor properties (certain organic compounds). The aerosol model found a condensable precursor concentration of at least 300 pptv was necessary to replicate the observations.
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Ebert, Rebecca L. "Case study of an anomalous, long-lived convective snowstorm /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1422923.
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Ghulam, Ayman S. "The development of a heavy thunderstorm climatology in Saudi Arabia based on observations, analyses and numerical simulations." Thesis, University of East Anglia, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436702.
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Abstract Thunderstorms can often result in direct threat to life and property when associated with heavy rain, hail, gusting wind and lightning. However, these events have received limited attention from a forecaster's and climatologist's point of view in Saudi Arabia. Meteorological research in Saudi Arabia has very limited; lack of data places severe restrictions on such work. The purpose of this research is to achieve a better understanding of thunderstorm formation in Saudi Arabia, advancing the understanding of the atmospheric processes that influence the initiation of storms and how they evolve over different types of terrain in Saudi Arabia; with the new datasets available now, this aim is possible. This study also aims to provide useful information on thunderstorm distribution and prediction to the local forecasters in Saudi Arabia to improve forecasting methods for all seasons. It was found that the study area presents many challenging meteorological problems. The synoptic climate has not previously been well documented and thereafter, it is poorly understood. Thus, this study provides, for the first time, a long term (44-year) synoptic climatology in Saudi Arabia based on ECMWF (ERA-40 reanalysis and operational) datasets. No thunderstorm climatology currently exists for Saudi Arabia; it is difficult to capture the high temporal/spatial variability of thunderstorms in Saudi Arabia due to lack of observation network coverage. Thus, this study has to include elements including satellite based data. By utilizing data from satellite-borne lightning detectors, is now possible to learn about thunderstorm distribution, especially in places where no enough surface stations such as Saudi Arabia. Reports of thunderstorms using surface observational data in Saudi Arabia are compared here with satellite based lightning data from the Lightning Imager Sensor (LIS) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite and with satellite based Outgoing Long-wave Radiation data, with strong agreement being found between them. Analysis of these data shows seasonal variability between various geographic regions. Although both frontal and air mass thunderstorms occur in Saudi Arabia spring months are characterized by particularly frequent thunderstorm activity in the kingdom. Furthermore, both LIS and OLR show, for the first time the distribution of lightning flashes over the central and southern Red Sea and over the Arabian Gulf where no observational stations. Thus, LIS and OLR can compensate the lack and fill in the gab of surface observations in Saudi Arabia. These results will help in flight route forecast in the future. The anomaly field on heavy thunderstorm days and on dry days was investigated to address the synoptic differences between dry and heavy thunderstorm days. The results highlighted the importance of number of key drives: surface disturbances, upper tropospheric mechanisms, sea breezes and instability due primarily to high insolation over the area. Severe thunderstorm occurrences in Saudi Arabia are associated with various types of weather systems, but synoptic typing in Saudi Arabia has not until now been carried out. Based on daily MSLP at 1200UTC, analyses of the synoptic situations accompanying heavy thunderstorms using, for the first time, a hybrid classification scheme combining subjective and objective methods showed that seven synoptic types are favourable for heavy thunderstorms formation. These patterns are: The Red Sea trough, the Red Sea trough combined with the Saudi low, the Middle East low, The Saudi low, the Mediterranean low, the Sudan trough combined with the Sahara low and the Indian monsoon trough. A comparison of subjective and objective classifications revealed that the classifications into these seven types match on more than half (52%) of the days, while 48% of the days were unclassified because of the subjectivity of manual classification. Local conditions determining spatial differentiation of thunderstorm occurrence in Saudi Arabia were also taken into consideration. Modelling work concerning meteorological issues is severely limited in Saudi Arabia. In this study the PSUINCAR MM5 model was adopted, for the first time, to simulate heavy thunderstorm events associated with rainfall (less than or equal to 10mm/day) to help simulate the synoptic and meso-scale environments conductive to heavy thunderstorm events in Saudi Arabia and understand their formation mechanisms. Three nested numerical experiments have been performed with grid resolutions of 135, 45, and 15 km. The spatial and temporal distribution of simulated heavy thunderstorms offered evidence linking to additional local effect factors such as terrain, high insolation leading to instability, low-level convergence zones, sea-land breezes and the interaction between flow and topography. Overall, this study presents information on the variability in thunderstorm occurrence in Saudi Arabia and pins-point favourable environmental and synoptic conditions, and the physical mechanisms of such phenomena in addition to numerical simulations of heavy thunderstorm events in Saudi Arabia.
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RONCALLO, LUCA. "Evolutionary spectral model for thunderstorm outflows and application to the analysis of the dynamic response of structures." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1080956.
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Thunderstorms are destructive phenomena at the mesoscale with extension of few kilometres and short duration, potentially dangerous for mid-low structures. The nonstationary nature of the wind field generated by thunderstorm outflows makes most of the theory and models developed for extra-tropical cyclones unsuitable and their small extension make them difficult to be detected by one single anemometer. These circumstances prevent the collection of precious data over which research can be carried out and the development of robust models for rapid engineering calculations shared by the scientific community. Therefore, a unified and reliable analytical model for the assessment of the maximum dynamic response to thunderstorms coherent with the techniques commonly adopted in wind engineering is not yet available. In this framework, the thesis introduces an Evolutionary Power Spectral Density (EPSD) model of the wind velocity related of thunderstorm outflows, consistent with full-scale records, and studies its application to calculate the alongwind dynamic response of structures and its maximum from an operative perspective.
The EPSD model is derived starting from the analysis of 129 full-scale thunderstorm records, assuming the turbulent fluctuations uniformly modulated and the turbulence intensity constant. The reliability of the assumptions are verified on the basis of the data available. Three analytical models for the modulating function of the slowly-varying mean wind velocity are proposed. The models are based on the functions extracted from the records and include parameters of physical meaning for the thunderstorm outflow. Moreover, the possibility of adopting the classical spectral models of synoptic winds to model the stationary part of the turbulence is verified. Successively, the EPSD model is adopted to calculate the dynamic response of a set of linear elastic point-like SDOF systems with variable fundamental frequency and damping ratio, both accounting and neglecting the effects of the transient dynamics. In this framework a closed-form solution of the Evolutionary Frequency Response Function (EFRF) is derived. The mean value of the maximum response is estimated based on an Equivalent Parameter Technique (EPT) from literature, generalizing the Davenport’s gust factor technique. The effects of the Poisson hypothesis are investigated and mitigated introducing an equivalent expected frequency. The results are validated with the ones obtained in the time domain starting from the real thunderstorm
records available. Successively, a sensitivity analysis is carried out to assess the influence on the maximum dynamic response of the parameters that shape the modulating function of the velocity.
A closed-form solution for the equivalent parameters and the gust factor is introduced. The comparison with alternative formulations proposed in the literature demonstrates the improved accuracy of the proposed one. Finally, the formulation is extended to the analysis of slender vertical structures, adopting a vertical profile for the mean wind velocity from the literature and the equivalent wind spectrum technique. Two case studies of vertical slender structures are analysed and a comparison with synoptic wind loading conditions is outlined, showing that the proposed model constitutes a valid and handy tool for the evaluation of the wind loading on structures provided by thunderstorm outflows.
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McCarthy, Alexander Michael. "Convective Cores in Continental and Oceanic Thunderstorms: Strength, Width, and Dynamics." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1493652830874675.
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Meyer, Vera. "Thunderstorm Tracking and Monitoring on the Basis of Three Dimensional Lightning Data and Conventional and Polarimetric Radar Data." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-121025.
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White, Megan L. "ASSOCIATING SEVERE THUNDERSTORM WARNINGS WITH DEMOGRAPHIC AND LANDSCAPE VARIABLES: A GEOGRAPHICALLY WEIGHTED REGRESSION-BASED MAPPING OF FORECAST BIAS." UKnowledge, 2014. http://uknowledge.uky.edu/geography_etds/20.
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Severe thunderstorm warnings (SVTs) are released by meteorologists in the local forecast offices of the National Weather Service (NWS). These warnings are issued with the intent of alerting areas in the path of severe thunderstorms that human and property risk are elevated, and that appropriate precautionary measures should be taken. However, studies have shown that the spatial distribution of severe storm warnings demonstrates bias. Greater numbers of severe thunderstorm warnings sometimes are issued where population is denser. By contrast, less populated areas may be underwarned. To investigate the spatial patterns of these biases for the central and southeastern United States, geographically weighted regression was implemented on a set of demographic and land cover descriptors to ascertain their patterns of spatial association with counts of National Weather Service severe thunderstorm warnings. GWR was performed for each our independent variables (total population, median income, and percent impervious land cover) and for all three of these variables as a group. Global R2 values indicate that each individual variable as well as all three collectively explain approximately 60% of the geographical variation in severe thunderstorm warning counts. Local R2 increased in the vicinity of several urban regions, notably Atlanta, Washington, D.C., St. Louis, and Nashville. However, the independent variables did not exhibit the same spatial patterning of R2. Some cities had high local R2 for all variables. Other cities exhibited high local R2 for only one or two of these independent variables. Median income had the highest local R2 values overall. Standardized residuals confirmed significant differences among several NWS forecast offices in the number and pattern of severe thunderstorm warnings. Overall, approximately half of the influences on the distribution of severe thunderstorm warnings across the study area are related to underlying land cover and demographics. Future studies may find it productive to investigate the extent to which the spatial bias mapped in this study is an artifact of forecast culture, background thunderstorm regime, or a product of urban anthropogenic weather modification.
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Thomas, Jeremy Norman. "Lightning-driven electric and magnetic fields measured in the stratosphere : implications for sprites /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/6838.
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Michaud, Jene Diane. "Distributed rainfall-runoff modeling of thunderstorm-generated floods a case study in a mid-sized, semi-arid watershed in Arizona /." Diss., The University of Arizona, 1992. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1992_49_sip1_w.pdf&type=application/pdf.
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Beveridge, Susan Lynn. "Quantifying the Relationship Between Southern-end Supercells and Tornado Production." Ohio University Honors Tutorial College / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1556127178521766.
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Gallagher, Frank Woolsey. "Green thunderstorms /." Full-text version available from OU Domain via ProQuest Digital Dissertations, 1997.
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CANEPA, FEDERICO. "Physical Investigation of Downburst Winds and Applicability to Full Scale Events." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1069704.
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Thunderstorm winds, i.e. downbursts, are cold descending currents originating from cumulonimbus clouds which, upon the impingement on the ground, spread radially with high intensities. The downdraft phase of the storm and the subsequent radial outflow that is formed can cause major issues for aviation and immense damages to ground-mounted structures. Thunderstorm winds present characteristics completely different from the stationary Gaussian synoptic winds, which largely affect the mid-latitude areas of the globe in the form of extra-tropical cyclones. Downbursts are very localized winds in both space and time. It follows that their statistical investigation, by means of classical full scale anemometric recordings, is often inadequate in the view of accurately reconstruct the transient nature of the phenomenon. Wind tunnel tests in ad-hoc laboratories can fill this gap. Furthermore, downbursts never occur as isolated system in nature; they occur, in fact, embedded into the background Atmospheric Boundary Layer (ABL) flow and are influenced by the thunderstorm cell translation. In nature, the decomposition of the recorded downburst signals into component signals associated with the aforementioned contributions is often challenging or unfeasible. This study presents the results of the largest experimental campaign performed so far on downburst winds, where the physical behavior of downburst-like flows, simulated by means of the impinging jet technique, was thoroughly investigated in the spatiotemporal domain. The experiments were conducted in the Wind Engineering, Energy and Environment (WinEEE) Dome at Western University which allows the simultaneous generation of downburst and background ABL winds along with the simulation of the parent thunderstorm translation. For the first time, a clear understanding of the overall downburst dynamics and of the interactions that take place during the occurrence of the phenomenon is presented. Later, this study investigates, as a structural application, the aerodynamic behavior of two cylinders subject to the experimentally produced downburst winds at the WindEEE Dome. Finally, the thesis describes the vertical profile time-evolution of full-scale downburst events recorded by means of the state-of-the-art LiDAR profiler, installed within the large wind monitoring network developed along the northern Tyrrhenian coasts during the European Project “Wind and Ports”, with the aim of comparing the respective wind fields with those reproduced at the WindEEE Dome. Common characteristics concerning the transiency of the phenomenon in terms of mean and turbulent part of the wind speed signals are found and reported in statistical manner. It is found that the direction can be dealt as invariant with the height, the height of the maximum velocity drops in correspondence of the absolute peak velocity, and turbulence presents its maxima shortly before the occurrence of the peak velocity. The implications of these findings in terms of structural response can be crucial.
This study is part of the wider project THUNDERR, whose Principal Investigator is Prof. Giovanni Solari, funded by an ERC Advanced Grant 2016. The project aims at finding a proper model of representation of thunderstorm winds, from the joint combination of physical, numerical, and analytical investigations, to be implemented in the calculation framework to assess the loading and response of structures to thunderstorm winds. The inclusion of an independent model for thunderstorm winds in the structural design codes, where the wind-structure interaction is still evaluated based on the synoptic-scale extra-tropical cyclones, would indeed represent a decisive turn. The problem is even more crucial in the view of the severe climate changes that are affecting the earth planet, which induce, as a consequence, a rising intensification and sharp increase in frequency of the extreme wind events, such as thunderstorms.
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Aiena, Christine N. "The Influence of the Wichita Mountain Range on Convection Initiation of Tornado and Large Hail Producing Supercells in Central Oklahoma." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou153374861711777.
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Murphy, Martin Joseph 1970. "The electrification of Florida thunderstorms." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/290670.
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Six thunderstorms that occurred at the NASA Kennedy Space Center, Florida, have been studied in an attempt to characterize their electrical structure and electrification. Ground-based measurements of the cloud electric fields, the locations of lightning VHF radio sources, cloud-to-ground lightning strike points, and dual-polarization radar data were used in this study. Changes in the electric field due to lightning were used to determine the locations and magnitudes of changes in cloud charge. The fields themselves were used to compute displacement current densities following lightning flashes. The altitudes of negative charge regions were between 6.5 and 8.5 km and were almost constant. The altitude of upper positive charge exhibited more variability, and usually increased as cells developed. Amounts of charge removed by lightning increased during each cell in large storms but were nearly constant during the early part of small storms. A lower positive charge center (LPCC) usually appeared in the fields before any other charge regions could be detected at the ground. A LPCC appeared to be involved in the initiation of the majority of CG flashes. During periods of lightning, a LPCC was sometimes created by a flash, but more typically, LPCCs were produced by a cloud charge separation process. Displacement current densities were used to estimate charge accumulation rates in the cloud. The rates derived for the main negative and upper positive charge regions were compared to the average rate of charge removal by lightning. The generation rates and average lightning currents each had values ranging from 0.2 to 1.5 A and were approximately equal within expected errors in single-cell storms. Once the storm was multicellular, however, the lightning current was larger than the cloud charging rate, possibly because lightning was removing residual charge from older cells. The cloud charging rates and average lightning currents were compared with the currents computed using a non-inductive ice-graupel charging mechanism and radar-derived cloud microphysical data. This mechanism provided currents that were comparable to the observed charging rates and lightning currents and appeared to be capable of producing the LPCC.
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Beneti, Cesar Augustus Assis. "Caracterização hidrodinâmica e elétrica de sistemas convectivos de mesoescala." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/14/14133/tde-18122012-190417/.
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A rotina operacional de monitoramento e previsão de tempo tem mudado bastante nos últimos anos. Além de informações convencionais existentes, que são bem conhecidas nos centros operacionais, os dados obtidos por sensoriamento remoto através de satélites, radares meteorológicos e sensores de detecção de descargas atmosféricas fornecem informações vitais e em tempo real, sendo estas as principais ferramentas para a detecção e previsão de tempestades severas. Na America do Sul, em especial o nordeste da Argentina, Paraguai, Uruguai e o sul do Brasil são regiões particularmente sujeitas a ocorrência de eventos severos (precipitação intensa, granizo, enchentes e intensa atividade elétrica, além de vendavais e tornados). No sul do Brasil, a distribuição mensal de chuvas é bastante uniforme, porém com alta variabilidade diária associada, principalmente, à passagem das frentes frias pela região e aos Sistemas Convectivos de Mesoescala, que se formam nessa região. A principal atividade econômica nessa região do Brasil é a agroindústria, diretamente dependente da distribuição da precipitação para a produção, como também susceptível aos fenômenos meteorológicos adversos associados. Além desta atividade, a região sul é responsável pela produção de, aproximadamente, 35% de toda a energia elétrica utilizada no país. O objetivo principal desta pesquisa foi estudar os aspectos espaciais e temporais da atividade elétrica durante os eventos de Sistemas Convectivos de Mesoescala (SCM) e examinar as possíveis relações entre o ambiente no qual essas tempestades se desenvolvem e as características elétricas e hidrometeorológicas desses, conforme observados por um radar meteorológico Doppler, e uma rede de detecção de relâmpagos, principalmente, e também com informações de satélites meteorológicos, dados de superfície e análises de modelos numéricos. Os resultados deste trabalho mostraram a importância das características dinâmicas na região, em especial a presença dos jatos em baixos níveis com a convergência de umidade na região para a organização dos eventos de SCM, como também a distribuição dos regimes de precipitação com características distintas de estrutura de refletividade observada por radar e também de atividade elétrica durante os eventos analisados. Espera-se que os resultados deste trabalho ajudem a entender melhor a relação dos sistemas convectivos de mesoescala e sua estrutura e evolução, como observados e detectados pelos sistemas remotos de monitoramento hidrometeorológico, além de um melhor entendimento e aperfeiçoamento de nossas habilidades de análise e previsão de tempo relacionados a esses eventos severos com precipitação intensa.The operational routine in weather monitoring and forecasting has changed a lot in the past years. Besides conventional information, well known in operational centers, data from remote sensing such as satellite, weather radars and lightning detection network provide vital information in real time, as the main tools for severe weather detection and forecasting In South America, specially northeastern Argentina, Paraguay, Uruguay and southern Brazil are regions prone to severe weather (intense precipitation, hail, floddings, lightning, tornadoes and gust winds). In the South of Brazil, monthly precipitation distribution is very uniform, but with daily variability associated, mostly, with the passage of cold fronts through the region and to mesoscale convective systems, forming in this area. The major economical activity in this region of Brazil is agroindustry, directly dependent of precipitation distribution for production and also susceptible to diverse meteorological events associated with it. Besides this activity, the south region is responsible for the production of, approximately, 35\\% of all electric energy used in the country. The main goal of this research was to study spatial and temporal aspects of the electrical activity during MCS events, as observed by a weather radar and a network of ligthning detection sensors in the south of Brazil, and to examine possible relations between the environment in which these storms develop and electrical characteristics of these weather systems, using weather radar, lightning, satellite and numerical model information. The results of this work showed the importance of the dynamic characteristics in the regial, specially the presence of low level jets and humidity convergence in the region to organize MCS events, as well as a distribution of precipitation regimes whith distinct characteristics of radar reflectivity and electrical activity during the analysed events. With this work we expect to contribute with the understanding of the relation of MCS structure and evolution as observed and detected by hydrometeorological monitoring systems and to improve the comprehension and ability to analyse and forecast such severe weather systems.
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Geis, Chad E. "Climate and weather analysis of Afghanistan thunderstorms." Thesis, Monterey, California. Naval Postgraduate School, 2011. http://hdl.handle.net/10945/5595.
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Approved for public release; distribution is unlimited.Thunderstorms are a significant factor in the planning and execution of Defense (DoD) operations in Afghanistan, especially in the spring and summer. Skillful forecasting of Afghanistan thunderstorms has proven difficult, even at relatively short lead times of 24 hours or less. This has led to adverse effects on a wide range of DoD missions. One potential reason for the forecasting difficulties is a lack of understanding of the conditions that lead to static instability and thunderstorms in the elevated desert mountain environment that characterizes much of Afghanistan. Much of the thunderstorm forecasting for Afghanistan is based on forecasting methods developed for the contiguous U.S. (CONUS)--for example, the use of CONUS-based static stability indices as indicators of the potential for thunderstorm development. We have investigated methods for improving thunderstorm forecasting in and near Kabul, Afghanistan, by: (1) analyzing interannual to hourly variations in thunderstorm activity; and (2) analyzing the large-scale conditions that are favorable and unfavorable for thunderstorms. We used in situ surface and radiosonde data to characterize the local conditions associated with thunderstorm variations. Our focus was on March-May, the period with the most thunderstorm activity in Kabul. We also used global reanalysis data to analyze the large-scale conditions that are favorable and unfavorable for thunderstorm development. We developed and tested two new static stability indices for use in Kabul. We also developed a large-scale circulation index to describe the regional factors that contribute to thunderstorm variations. Finally, we identified outgoing longwave radiation anomalies that occurred in specific tropical ocean basins as potential precursors for predicting thunderstorm and nonthunderstorm events at lead times of 5-15 days.
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Thornhill, Kenneth L. II. "An investigation of the environment surrounding supercell thunderstorms using wind profiler data." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/26958.
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Kozak, Steven Alexander. "Lightning strikes in Alberta thunderstorms, climatology and case studies." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0006/MQ34385.pdf.
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Koshak, William John. "Analysis of lightning field changes produced by Florida thunderstorms." Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/185259.
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An interactive computer program .has been developed to compute accurate values of lightning-caused changes in the cloud electric field (ΔE). The ΔE' s for individual discharges in eight Florida thunderstorms have been analyzed using a nonlinear, least-squares minimization procedure and point charge (Q) and point dipole (P) models of the change in cloud charge. The results indicate that the temporal and spatial behavior of the Q- and P- model parameters are similar to those reported previously by Koshak and Krider [1989]. In all storms, the high altitude P-vectors tend to point downward toward a narrow altitude band of Q-solutions that is centered at about 8 km; low altitude P-vectors tend to point upward toward the Q-region: and the P-vectors that are at the same altitude as the Q-solutions tend to be horizontal. Because there are inherent limitations in the above least-squares analysis method and models, a new, fundamentally different approach for analyzing lightning field changes has been developed. This method finds an optimum volume charge distribution on a grid of finite dimensions and resolution. with this linear approach, we now have the ability to describe complex field change patterns subject to a variety of external constraints. We also have a framework in which a standard eigenanalysis can be used to access the general information content of data and the effects of measurement errors. Tests of the linear method with simulated lightning sources show that a centroid of the lightning charge distribution can be retrieved to within the grid resolution (2 km) when a Landweber iterative algorithm is used. Tests on three natural lightning events show that there is good agreement with previous Q- and P- model solutions and a resonable result for one event that could not be described with either a Q- or a Pmodel.
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Becker, Amy E. "A study of lightning flashes attending periods of banded heavy snowfall." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/6036.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on November 11, 2008) Vita. Includes bibliographical references.