Matching Items (12)

Long-Term Associations Between Wind Speeds and the Urban Heat Island of Phoenix, Arizona

Description

The association between a developing urban heat island and local monthly averaged wind speeds is examined in this investigation. Results from a series of statistical analyses show a significant increase

The association between a developing urban heat island and local monthly averaged wind speeds is examined in this investigation. Results from a series of statistical analyses show a significant increase in wind speeds in Phoenix, Arizona during the period of rapid heat island development. The increase in winds is found to be much stronger at 0500 MST than at 1400 MST. Increased instability and the development of a strong heat low circulation in the urban environment are suggested as probable causes for the increased wind speeds.

Contributors

Created

Date Created
  • 1987-06-01

155022-Thumbnail Image.png

Climate resilience and vulnerability of the Salt River Project reservoir system, present and future

Description

Water resource systems have provided vital support to transformative growth in the Southwest United States; and for more than a century the Salt River Project (SRP) has served as a

Water resource systems have provided vital support to transformative growth in the Southwest United States; and for more than a century the Salt River Project (SRP) has served as a model of success among multipurpose federal reclamation projects, currently delivering approximately 40% of water demand in the metropolitan Phoenix area. Drought concerns have sensitized water management to risks posed by natural variability and forthcoming climate change.

Full simulations originating in climate modeling have been the conventional approach to impacts assessment. But, once debatable climate projections are applied to hydrologic models challenged to accurately represent the region’s arid hydrology, the range of possible scenarios enlarges as uncertainties propagate through sequential levels of modeling complexity. Numerous issues render future projections frustratingly uncertain, leading many researchers to conclude it will be some decades before hydroclimatic modeling can provide specific and useful information to water management.

Alternatively, this research investigation inverts the standard approach to vulnerability assessment and begins with characterization of the threatened system, proceeding backwards to the uncertain climate future. Thorough statistical analysis of historical watershed climate and runoff enabled development of (a) a stochastic simulation methodology for net basin supply (NBS) that renders the entire range of droughts, and (b) hydrologic sensitivities to temperature and precipitation changes. An operations simulation model was developed for assessing the SRP reservoir system’s cumulative response to inflow variability and change. After analysis of the current system’s drought response, a set of climate change forecasts for the balance of this century were developed and translated through hydrologic sensitivities to drive alternative NBS time series assessed by reservoir operations modeling.

Statistically significant changes in key metrics were found for climate change forecasts, but the risk of reservoir depletion was found to remain zero. System outcomes fall within ranges to which water management is capable of responding. Actions taken to address natural variability are likely to be the same considered for climate change adaptation. This research approach provides specific risk assessments per unambiguous methods grounded in observational evidence in contrast to the uncertain projections thus far prepared for the region.

Contributors

Agent

Created

Date Created
  • 2016

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

155721-Thumbnail Image.png

Regional famine patterns of the last millennium as influenced by aggregated climate teleconnections

Description

ABSTRACT

Famine is the result of a complex set of environmental and social factors. Climate conditions are established as environmental factors contributing to famine occurrence, often through teleconnective patterns. This dissertation

ABSTRACT

Famine is the result of a complex set of environmental and social factors. Climate conditions are established as environmental factors contributing to famine occurrence, often through teleconnective patterns. This dissertation is designed to investigate the combined influence on world famine patterns of teleconnections, specifically the North Atlantic Oscillation (NAO), Southern Oscillation (SO), Pacific Decadal Oscillation (PDO), Atlantic Multidecadal Oscillation (AMO), or regional climate variations such as the South Asian Summer Monsoon (SASM). The investigation is three regional case studies of famine patterns specifically, Egypt, the British Isles, and India.

The first study (published in Holocene) employs the results of a Principal Component Analysis (PCA) yielding a SO-NAO eigenvector to predict major Egyptian famines between AD 1049-1921. The SO-NAO eigenvector (1) successfully discriminates between the 5-10 years preceding a famine and the other years, (2) predicts eight of ten major famines, and (3) correctly identifies fifty out of eighty events (63%) of food availability decline leading up to major famines.

The second study investigates the impact of the NAO, PDO, SO, and AMO on 63 British Isle famines between AD 1049 and 1914 attributed to climate causes in historical texts. Stepwise Regression Analysis demonstrates that the 5-year lagged NAO is the primary teleconnective influence on famine patterns; it successfully discriminates 73.8% of weather-related famines in the British Isles from 1049 to 1914.

The final study identifies the aggregated influence of the NAO, SO, PDO, and SASM on 70 Indian famines from AD 1049 to 1955. PCA results in a NAO-SOI vector and SASM vector that predicts famine conditions with a positive NAO and negative SO, distinct from the secondary SASM influence. The NAO-famine relationship is consistently the strongest; 181 of 220 (82%) of all famines occurred during positive NAO years.

Ultimately, the causes of famine are complex and involve many factors including societal and climatic. This dissertation demonstrates that climate teleconnections impact famine patterns and often the aggregates of multiple climate variables hold the most significant climatic impact. These results will increase the understanding of famine patterns and will help to better allocate resources to alleviate future famines.

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

157061-Thumbnail Image.png

Atmospheric sounding data as tools for forecasting severe hail and ozone accumulation in Arizona during the North American monsoon

Description

Monsoon hazards routinely affect the community, economy, and environment of the American Southwest. A common link for hazard development during the North American Monsoon concerns the interplay between temperature, moisture,

Monsoon hazards routinely affect the community, economy, and environment of the American Southwest. A common link for hazard development during the North American Monsoon concerns the interplay between temperature, moisture, and wind in the vertical atmosphere controlled by an unstable monsoon circulation. This dissertation investigates vertical atmospheric patterns using in-situ sounding data, specifically, 1) environments favorable for severe hail on the Colorado Plateau, 2) significant parameters distinguishing unhealthy versus healthy ozone days in Phoenix, Arizona, and 3) vertical profile alignments associated with distinct ranges in ozone concentrations observed in Phoenix having defined health impacts.

The first study (published in the Journal of the Arizona-Nevada Academy of Science) determines significant variables on Flagstaff, Arizona 12Z rawinsonde data (1996-2009) found on severe hail days on the Colorado Plateau. Severe hail is related to greater sub-300 hectopascals (hPa) moisture, a warmer atmospheric column, lighter above surface wind speeds, more southerly to southeasterly oriented winds throughout the vertical (except at the 700 hPa pressure level), and higher geopotential heights.

The second study (published in Atmospheric Environment) employs principal component, linear discriminant, and synoptic composite analyses using Phoenix, Arizona rawinsonde data (2006-2016) to identify common monsoon patterns affecting ozone accumulation in the Phoenix metropolitan area. Unhealthy ozone occurs with amplified high-pressure ridging over the Four Corners region, 500 hPa heights often exceeding 5910 meters, surface afternoon temperatures typically over 40°C, lighter wind speeds in the planetary boundary layer under four ms-1, and persistent light easterly flow between 700-500 hPa countering the daytime mountain-valley circulation.

The final study (under revision in Weather and Forecasting) assesses composite atmospheric sounding analysis to forecast Air Quality Index ozone classifications of Good, Moderate, and collectively categories exceeding the U.S. EPA 2015 standard. The analysis, using Phoenix 12Z rawinsonde data (2006-2017), identifies the existence of “pollutant dispersion windows” for ozone accumulation and dispersal in Phoenix.

Ultimately, monsoon hazards result from a complex and evolving vertical atmosphere. This dissertation demonstrates the viability using available in-situ vertical upper-air data to anticipate recurring atmospheric states contributing to specific hazards. These results will improve monsoon hazard prediction in an effort to protect public and infrastructure.

Contributors

Agent

Created

Date Created
  • 2019

150690-Thumbnail Image.png

Climatological isentropic analysis: identifying patterns associated with tornado occurrences across the United States

Description

Isentropic analysis is a type of analysis that is based on using the concept of potential temperatures, the adiabatically established temperature at 1000 hPa. In the 1930s and 1940s this

Isentropic analysis is a type of analysis that is based on using the concept of potential temperatures, the adiabatically established temperature at 1000 hPa. In the 1930s and 1940s this type of analysis proved to be valuable in indicating areas of increased moisture content and locations experiencing flow up or down adiabatic surfaces. However, in the early 1950s, this type of analysis faded out of use and not until the twenty-first century have some researchers started once again to examine the usefulness of isentropic analysis. One aspect in which isentropic analysis could be practical, based on prior research, is in severe weather situations, due to its ability to easily show adiabatic motion and moisture. As a result, I analyzed monthly climatological isentropic surfaces to identify distinct patterns associated with tornado occurrences for specific regions and months across the contiguous United States. I collected tornado reports from 1974 through 2009 to create tornado regions for each month across the contiguous United States and corresponding upper air data for the same time period. I then separated these upper air data into tornado and non-tornado days for specific regions and conducted synoptic and statistical analyses to establish differences between the two. Finally, I compared those results with analyses of individual case studies for each defined region using independent data from 2009 through 2010. On tornado days distinct patterns can be identified on the isentropic surface: (1) the average isentropic surface lowered on tornado days indicating a trough across the region, (2) a corresponding increase in moisture content occurred across the tornado region, and (3) wind shifted in such a manner to produce flow up the isentropic trough indicating uplift. When comparing the climatological results with the case studies, the isentropic pattern for the case studies in general was more pronounced compared to the climatological pattern; however, this would be expected as when creating the average the pattern/conditions will be smoothed. These findings begin to bridge the large gap in literature, show the usefulness of isentropic analysis in monthly and daily use and serve as catalysts to create a finer resolution database in isentropic coordinates.

Contributors

Agent

Created

Date Created
  • 2012

152041-Thumbnail Image.png

The 500hPa wintertime Pacific ridge: characteristics of position and intensity and its influence on Southwest U.S. precipitation

Description

The characteristics of the wintertime 500hPa height surface, the level of non-divergence and used for identifying/observing synoptic-scale features (ridges and troughs), and their impact on precipitation are of significance to

The characteristics of the wintertime 500hPa height surface, the level of non-divergence and used for identifying/observing synoptic-scale features (ridges and troughs), and their impact on precipitation are of significance to forecasters, natural resource managers and planners across the southwestern United States. For this study, I evaluated the location of the 500hPa mean Pacific ridge axis over the winter for the period of 1948/49 to 2011/12 and derived the mean ridge axis in terms of location (longitude) and intensity (geopotential meters) from the NCEP/NCAR Reanalysis dataset. After deriving a mean ridge axis climatology and analyzing its behavior over time, I correlated mean location and intensity values to observed wintertime precipitation in select U.S. Climate Divisions in Arizona, Colorado, Nevada, Utah and New Mexico. This resulted in two findings. First specific to the 500hPa ridge behavior, the ridge has been moving eastward and also has been intensifying through time. Second, results involving correlation tests between mean ridge location and intensity indicate precipitation across the selected Southwest Climate Divisions are strongly related to mean ridge intensity slightly more than ridge location. The relationships between mean ridge axis and observed precipitation also are negative, indicating an increase of one of the ridge parameters (i.e. continued eastward movement or intensification) lead to drier winter seasons across the Southwest. Increased understanding of relationships between upper-level ridging and observed wintertime precipitation aids in natural resource planning for an already arid region that relies heavily on winter precipitation.

Contributors

Agent

Created

Date Created
  • 2013

151767-Thumbnail Image.png

Short term exogenic climate change forcing

Description

Several short term exogenic forcings affecting Earth's climate are but recently identified. Lunar nutation periodicity has implications for numerical meteorological prediction. Abrupt shifts in solar wind bulk velocity, particle density,

Several short term exogenic forcings affecting Earth's climate are but recently identified. Lunar nutation periodicity has implications for numerical meteorological prediction. Abrupt shifts in solar wind bulk velocity, particle density, and polarity exhibit correlation with terrestrial hemispheric vorticity changes, cyclonic strengthening and the intensification of baroclinic disturbances. Galactic Cosmic ray induced tropospheric ionization modifies cloud microphysics, and modulates the global electric circuit. This dissertation is constructed around three research questions: (1): What are the biweekly declination effects of lunar gravitation upon the troposphere? (2): How do United States severe weather reports correlate with heliospheric current sheet crossings? and (3): How does cloud cover spatially and temporally vary with galactic cosmic rays? Study 1 findings show spatial consistency concerning lunar declination extremes upon Rossby longwaves. Due to the influence of Rossby longwaves on synoptic scale circulation, our results could theoretically extend numerical meteorological forecasting. Study 2 results indicate a preference for violent tornadoes to occur prior to a HCS crossing. Violent tornadoes (EF3+) are 10% more probable to occur near, and 4% less probable immediately after a HCS crossing. The distribution of hail and damaging wind reports do not mirror this pattern. Polarity is critical for the effect. Study 3 results confirm anticorrelation between solar flux and low-level marine-layer cloud cover, but indicate substantial regional variability between cloud cover altitude and GCRs. Ultimately, this dissertation serves to extend short term meteorological forecasting, enhance climatological modeling and through analysis of severe violent weather and heliospheric events, protect property and save lives.

Contributors

Agent

Created

Date Created
  • 2013