Matching Items (22)

134565-Thumbnail Image.png

A Numerical and Analytical Study of Wave Reflection and Transmission across the Tropopause

Description

A numerical study of wave-induced momentum transport across the tropopause in the presence of a stably stratified thin inversion layer is presented and discussed. This layer consists of a shar

A numerical study of wave-induced momentum transport across the tropopause in the presence of a stably stratified thin inversion layer is presented and discussed. This layer consists of a sharp increase in static stability within the tropopause. The wave propagation is modeled by numerically solving the Taylor-Goldstein equation, which governs the dynamics of internal waves in stably stratified shear flows. The waves are forced by a flow over a bell shaped mountain placed at the lower boundary of the domain. A perfectly radiating condition based on the group velocity of mountain waves is imposed at the top to avoid artificial wave reflection. A validation for the numerical method through comparisons with the corresponding analytical solutions will be provided. Then, the method is applied to more realistic profiles of the stability to study the impact of these profiles on wave propagation through the tropopause.

Contributors

Created

Date Created
  • 2017-05

137869-Thumbnail Image.png

Today the Weather is...: Educational Tools for Weather Map Reading and Weather Forecasting

Description

Meteorology is an uncommon term rarely resonating through elementary classrooms. However, it is a concept found in both fourth and sixth grade Arizona science standards. As issues involving the environment

Meteorology is an uncommon term rarely resonating through elementary classrooms. However, it is a concept found in both fourth and sixth grade Arizona science standards. As issues involving the environment are becoming more pertinent, it is important to study and understand atmospheric processes along with fulfilling the standards for each grade level. This thesis project teaches the practical skills of weather map reading and weather forecasting through the creation and execution of an after school lesson with the aide of seven teen assistants.

Contributors

Agent

Created

Date Created
  • 2012-12

133023-Thumbnail Image.png

Identifying Synoptic Patterns Associated with Deadly Tornadoes in the Mid-South

Description

The Mid-South region, which consists of west Tennessee, northeast Arkansas, north Mississippi, and the Missouri bootheel, is one of many areas in the United States that frequently faces the threats

The Mid-South region, which consists of west Tennessee, northeast Arkansas, north Mississippi, and the Missouri bootheel, is one of many areas in the United States that frequently faces the threats to life and property posed by tornadoes. Forecasting the occurrence of tornadoes is arguably the biggest challenge for meteorologists responsible for the region. This study analyzes synoptic scale weather conditions associated with tornadoes in the Mid-South with the hopes of identifying patterns conducive to tornadic activity and that these patterns can be used to better forecast potential tornado days. It is hypothesized that patterns associated with tornado formation can be identified and that certain patterns may be more favorable to stronger tornadoes or tornado outbreaks than others.
To find these patterns, I analyzed surface and upper air features were analyzed on days where multiple tornadoes occurred from January 1999 to March 2018. Specifically, the surface low pressure, 500hPa trough, and 850 and 300hPa jets were analyzed. Using a floating nine point grid system, I identified the location of the Mid-South in relation to the feature. In the end, eight patterns of similar grid locations were identified to be related to tornado days. For example, the Mid-South was frequently to the southeast of the surface low. However, no correlation appears to exist between the patterns and the number or intensity of tornadoes. It is recommended that in the future these patterns be tested as a forecast method and/or compared to non-tornado days to verify that they are valid tools.

Contributors

Agent

Created

Date Created
  • 2019-05

158204-Thumbnail Image.png

Impact Assessments of Extreme Weather Events using Geographical Approaches

Description

Recent extreme weather events such the 2020 Nashville, Tennessee tornado and Hurricane Maria highlight the devastating economic losses and loss of life associated with weather-related disasters. Understanding the impacts of

Recent extreme weather events such the 2020 Nashville, Tennessee tornado and Hurricane Maria highlight the devastating economic losses and loss of life associated with weather-related disasters. Understanding the impacts of extreme weather events is critical to mitigating disaster losses and increasing societal resilience to future events. Geographical approaches are best suited to examine social and ecological factors in extreme weather event impacts because they systematically examine the spatial interactions (e.g., flows, processes, impacts) of the earth’s system and human-environment relationships. The goal of this research is to demonstrate the utility of geographical approaches in assessing social and ecological factors in extreme weather event impacts. The first two papers analyze the social factors in the impact of Hurricane Sandy through the application of social geographical factors. The first paper examines how knowledge disconnect between experts (climatologists, urban planners, civil engineers) and policy-makers contributed to the damaging impacts of Hurricane Sandy. The second paper examines the role of land use suitability as suggested by Ian McHarg in 1969 and unsustainable planning in the impact of Hurricane Sandy. Overlay analyses of storm surge and damage buildings show damage losses would have been significantly reduced had development followed McHarg’s suggested land use suitability. The last two papers examine the utility of Unpiloted Aerial Systems (UASs) technologies and geospatial methods (ecological geographical approaches) in tornado damage surveys. The third paper discusses the benefits, limitations, and procedures of using UASs technologies in tornado damage surveys. The fourth paper examines topographical influences on tornadoes using UAS technologies and geospatial methods (ecological geographical approach). This paper highlights how topography can play a major role in tornado behavior (damage intensity and path deviation) and demonstrates how UASs technologies can be invaluable tools in damage assessments and improving the understanding of severe storm dynamics (e.g., tornadic wind interactions with topography). Overall, the significance of these four papers demonstrates the potential to improve societal resilience to future extreme weather events and mitigate future losses by better understanding the social and ecological components in extreme weather event impacts through geographical approaches.

Contributors

Agent

Created

Date Created
  • 2020

154527-Thumbnail Image.png

Weathercasters in local television news: a qualitative case study of culture and technology in a large U.S. broadcasting market during the monsoon

Description

This is a case study of weathercasters in a large U.S. television market from five different English speaking stations conducted before, during, and after a severe weather season. The

This is a case study of weathercasters in a large U.S. television market from five different English speaking stations conducted before, during, and after a severe weather season. The research applies the ethnographic process to inscribe and define the culture of local weathercasters in the news environment. The purpose of this study is to examine the extant cultural characteristics discerned by weathercasters and the changes in weather broadcast technology used by live “on-air” television personnel. Forty-nine elite, in depth interviews with 17 different weathercasters along with participant and non-participant observation yielded transcripts and field notes obtained during the six month data acquisition phase. Using qualitative methods and the CAQDAS program Dedoose, 953 coded excerpts from the transcripts were analyzed for various patterns, behaviors, and characteristics relevant to culture, technology, and perceptions of weathercasters. The excerpts revealed dominant cultural aspects defined as dichotomous differences, autonomous functions, and identity perceptions. Socio-technical models are explicated in relationship to control, knowledge, and strategic coping mechanisms. The newsroom and weathercaster co-cultural context is defined by the conformity versus autonomy relationship and the external and internal structure of the weathercaster’s working environment is delineated. Co-cultural models explain the way influence operates in severe weather situations within the newsroom culture. The results have utility for scholars studying technology, culture, newsroom routines, rituals, and professionals who work in the television news industry. The findings are highly relevant for television weathercasters, newsroom producers, and broadcast managers.

Contributors

Agent

Created

Date Created
  • 2016

154673-Thumbnail Image.png

Synoptic typing of high ozone events in Arizona (2011-2013)

Description

This thesis examines the synoptic characteristics associated with ozone exceedance events in Arizona during the time period of 2011 to 2013. Finding explanations and sources to the ground level ozone

This thesis examines the synoptic characteristics associated with ozone exceedance events in Arizona during the time period of 2011 to 2013. Finding explanations and sources to the ground level ozone in this state is crucial to maintaining the state’s adherence to federal air quality regulations. This analysis utilizes ambient ozone concentration data, surface meteorological conditions, upper air analyses, and HYSPLIT modeling to analyze the synoptic characteristics of ozone events. Based on these data and analyses, five categories were determined to be associated with these events. The five categories all exhibit distinct upper air patterns and surface conditions conducive to the formation of ozone, as well as distinct potential transport pathways of ozone from different nearby regions. These findings indicate that ozone events in Arizona can be linked to synoptic-scale patterns and potential regional transport of ozone. These results can be useful in the forecasting of high ozone pollution and influential on the legislative reduction of ozone pollution.

Contributors

Agent

Created

Date Created
  • 2016

155716-Thumbnail Image.png

Relationship between surface dewpoint and precipitable water during the North American monsoon

Description

The North American Monsoon (NAM) is a late summer increase in precipitation fundamentally caused by a wind shift that is evident in the southwestern United States and northwest Mexico from

The North American Monsoon (NAM) is a late summer increase in precipitation fundamentally caused by a wind shift that is evident in the southwestern United States and northwest Mexico from approximately June-August. Increased precipitation during these months bring an increased regional threat from heavy rains, blowing dust, and damaging storms. (Adams and Comrie 1997). Researchers in Phoenix, AZ theorized that using surface dewpoint measurements was an objective way to officially mark the start of the NAM in Phoenix, AZ (and Tucson, AZ). Specifically, they used three consecutive days at or above a certain dewpoint temperature (Franjevic 2017). The justification for this method was developed by Reitan (1957) who established that 25.4mm (1.00”) of integrated precipitable water (IPW) was a sufficient threshold to create storm activity in the NAM region. He also determined (Reitan 1963) that a strong correlation existed between (IPW) and surface dewpoint (Td), whereas, Td could be used as a proxy to determine IPW.

I hypothesize that the correlation coefficients between IPW and Td will be greatest when using seasonal mean averages of IPW and Td, and they will decrease with shortened mean timescales (from seasonal to three-days). Second, I hypothesize that there is a unique relationship between IPW/Td that may signal monsoon onset. To conduct this study, I used the North American Regional Reanalysis (NARR) dataset (1979-2015). For ten locations in the Southwest, I conducted a series of statistical analyses between IPW, Td, and accumulated precipitation. I determined that there is a correlation between the two as set forth by Reitan (1963) as well as (Benwell 1965; Smith 1966; Ojo 1970). However, from the results I concluded this relationship is highly variable, spatially and temporally. Additionally, when comparing the three-hour, three-day, and the weekly mean measurements, I can conclude that, for my study, timescale averaging did enhance the IPW/Td relationship from three-hour to weekly as expected. The temporal and spatial evolution of the IPW/Td correlation as presented in this thesis may provide a framework for future research that reevaluates the NAM’s domain and the associated methods for determining its onset.

Contributors

Agent

Created

Date Created
  • 2017

157144-Thumbnail Image.png

A spatial analysis of "most weather warned" counties by severe weather phenomena in the contiguous United States

Description

Severe weather affects many regions of the United States, and has potential to greatly impact many facets of society. This study provides a climatological spatial analysis by county of severe

Severe weather affects many regions of the United States, and has potential to greatly impact many facets of society. This study provides a climatological spatial analysis by county of severe weather warnings issued by the National Weather Service (NWS) between January 1st, 1986 to December 31st, 2017 for the contiguous United States. The severe weather warnings were issued for county-based flash flood, severe thunderstorm, and tornado phenomena issued through the study period and region. Post 2002 severe weather warnings issued by storm warning area were included in this study in the form of county-based warnings simultaneously issued for each affected county. Past studies have researched severe weather warnings issued by the NWS, however these studies are limited in geographic representation, study period, and focused on population bias. A spatial analysis of severe weather warning occurrences by county identify that (a) highest occurrences of flash flood warnings are located in the desert Southwest and Texas, (b) severe thunderstorm warning occurrence is more frequent in Arizona, portions of the Midwest, the South, and the Mid and South Atlantic states, (c) the tornado activity regions of Tornado Alley and Dixie Alley (i.e. Colorado, Kansas, Oklahoma, Arkansas, Texas, Louisiana, Mississippi, Alabama, Tennessee, and Illinois) contained the highest occurrences of tornado warnings, and (d) the highest instances of aggregate warning occurrences are found in the desert Southwest, the Midwest, and the Southern regions of the United States. Generally, severe weather warning “hot spots” tend to be located in those same regions, with greater coverage. This study concludes with a comparison of local maxima and general hot spot regions to expected regions for each phenomenon. Implications of this study are far reaching, including emergency management, and has potential to reduce risk of life.

Contributors

Agent

Created

Date Created
  • 2019

149693-Thumbnail Image.png

Acclimation's influence on physically-fit individuals: marathon race results as a function of meteorological variables and indices

Description

While there are many elements to consider when determining one's risk of heat or cold stress, acclimation could prove to be an important factor to consider. Individuals who are

While there are many elements to consider when determining one's risk of heat or cold stress, acclimation could prove to be an important factor to consider. Individuals who are participating in more strenuous activities, while being at a lower risk, will still feel the impacts of acclimation to an extreme climate. To evaluate acclimation in strenuous conditions, I collected finishing times from six different marathon races: the New York City Marathon (New York City, New York), Equinox Marathon (Fairbanks, Alaska), California International Marathon (Sacramento, California), LIVESTRONG Austin Marathon (Austin, Texas), Cincinnati Flying Pig Marathon (Cincinnati, Ohio), and the Ocala Marathon (Ocala, Florida). Additionally, I collected meteorological variables for each race day and the five days leading up to the race (baseline). I tested these values against the finishing times for the local runners, those from the race state, and visitors, those from other locations. Effects of local acclimation could be evaluated by comparing finishing times of local runners to the change between the race day and baseline weather conditions. Locals experienced a significant impact on finishing times for large changes between race day and the baseline conditions for humidity variables, dew point temperature, vapor pressure, relative humidity, and temperature based variables such as the heat index, temperature and the saturation vapor pressure. Wind speed and pressure values also marked a change in performance, however; pressure was determined to be a larger psychological factor than acclimation factor. The locals also demonstrated an acclimation effect as performance improved when conditions were similar on race day to baseline conditions for the three larger races. Humidity variables had the largest impact on runners when those values increased from training and acclimation values; however increased wind speed appeared to offset increased humidity values. These findings support previous acclimation research stating warm wet conditions are more difficult to acclimate to than warm dry conditions. This research while primarily pertaining to those participating physically demanding activities may also be applied to other large scale events such as festivals, fairs, or concerts.

Contributors

Agent

Created

Date Created
  • 2011

149581-Thumbnail Image.png

Microscale modeling of the canopy-layer urban heat island In Phoenix, Arizona: validation and sustainable mitigation scenarios

Description

Metropolitan Phoenix, Arizona, is one of the most rapidly urbanizing areas in the U.S., which has resulted in an urban heat island (UHI) of substantial size and intensity. Several detrimental

Metropolitan Phoenix, Arizona, is one of the most rapidly urbanizing areas in the U.S., which has resulted in an urban heat island (UHI) of substantial size and intensity. Several detrimental biophysical and social impacts arising from the large UHI has posed, and continues to pose, a challenge to stakeholders actively engaging in discussion and policy formulation for a sustainable desert city. There is a need to mitigate some of its detrimental effects through sustainable methods, such as through the application of low-water, desert-adapted low-water use trees within residential yards (i.e. urban xeriscaping). This has the potential to sustainably reduce urban temperatures and outdoor thermal discomfort in Phoenix, but evaluating its effectiveness has not been widely researched in this city or elsewhere. Hence, this dissertation first evaluated peer-reviewed literature on UHI research within metropolitan Phoenix and discerned several major themes and factors that drove existing research trajectories. Subsequently, the nocturnal cooling influence of an urban green-space was examined through direct observations and simulations from a microscale climate model (ENVI-Met 3.1) with an improved vegetation parameterization scheme. A distinct park cool island (PCI) of 0.7-3.6 °C was documented from traverse and model data with larger magnitudes closer to the surface. A key factor in the spatial expansion of PCI was advection of cooler air towards adjacent urban surfaces, especially at 0-1 m heights. Modeled results also possessed varying but reasonable accuracy in simulating temperature data, although some systematic errors remained. Finally, ENVI-Met generated xeriscaping scenarios in two residential areas with different surface vegetation cover (mesic vs. xeric), and examined resulting impacts on near-surface temperatures and outdoor thermal comfort. Desert-adapted low-water use shade trees may have strong UHI mitigation potential in xeric residential areas, with greater cooling occurring at (i.) microscales (~2.5 °C) vs. local-scales (~1.1 °C), and during (ii.) nocturnal (0500 h) vs. daytime periods (1700 h) under high xeriscaping scenarios. Conversely, net warming from increased xeriscaping occurred over mesic residential neighborhoods over all spatial scales and temporal periods. These varying results therefore must be considered by stakeholders when considering residential xeriscaping as a UHI mitigation method.

Contributors

Agent

Created

Date Created
  • 2011