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Dust storms are linked to large scale accidents and fatalities in the Central Sonoran Desert, specifically in the central Gila River Valley of the United States during the North American Monsoon. This study analyzes three events where the underlying topography impacts large summertime dust storms and their movement. All three examples demonstrate the shielding or, conversely, funneling effects associated the underlying terrain. The funneling between isolated mountain complexes, such as White Tank Mountains, the Sierra Estrella, the Sacaton Mountains, the San Tan Mountains, and the South Mountain Complex can combine to create substantially higher dust concentrations. Conversely, dust flow into these isolated mountain complexes can also lead to shielding, or blocking, of the dust such that area behind the topographic features experiences less dust while the windward side of the barriers have accented dust concentrations. These dust storm/topography studies provide a first opportunity to identify topographic influences on central Arizona dust storms. The purpose of this study is to identify Topographic elements of the central Sonoran Desert located in the Arizona region of the Southwestern United States that impact the movement of dust storms. Using IDW interpolation to analyze PM10 concentration levels and wind speeds, we find that stand-alone mountain complexes can provide significant dust shielding and funneling that effect the overall trajectory of a dust storm in this region. • Identification of topographic elements impacting the movement of dust storms in the central Sonoran Desert located in the Arizona region of the Southwestern United States. • Use of IDW Interpolation for PM10 concentrations and wind speeds for dust storms. • Use of NEXRAD level II base reflectivity data for dust storms. • South Mountain Complex and the Sierra Estrella act as a dust shield inhibiting the flow of dust to the North. [ABSTRACT FROM AUTHOR]

We use a combination of a regional climate model (RCM) and a global climate model (GCM) to explore potential changes to the complex precipitation regime in the semi‐arid and arid state of Arizona in the American Southwest. The RCM output for the contemporary period (2000–2009) compares well with a gridded precipitation dataset with respect to seasonality, amount, intensity, and diurnal patterns. Output from the GCM forced by the continued buildup of greenhouse gases was dynamically downscaled by the RCM for the period 2090–2099. Results indicate an increase in winter precipitation of 1–2 mm day−1 in the mountainous areas of the state with somewhat smaller increases for the summer and fall seasons; negligible changes were projected for spring precipitation. Extreme precipitation is projected to increase across much of the state in winter (10–30 mm day−1) and to a lesser extent in spring. Our results indicate an increase in the 99th percentile of winter season precipitation. However, we note there is substantial seasonal dependency: statewide‐averaged winter season precipitation is projected to undergo greater frequency of wet than dry extreme events, whereas the statewide‐averaged summer, fall, and spring seasons, broadly demonstrate an equal likelihood of increased and decreased extreme precipitation. While the RCM captured the unusual observed night‐time maximum in summer rainfall in the centre of the state, our results do not indicate any change in the diurnal character or sub‐diurnal duration (6–18 hr) of precipitation over the next 100 years. [ABSTRACT FROM AUTHOR]

Dust storms are a major cause of central Sonoran Desert weather fatalities. Through back-trajectory analysis of North American Monsoon dust storms in central Sonoran Desert of the United States. This study is specific to central Arizona (USA) from 2009 to 2022 using the HYSPLIT model. Our findings have shown that dust storms originate from southerly or near-southerly regions. The dust storms displaying the highest concentrations of particulates show a preference to originate from the southwest. This coincides with the development of a 500 hPa ridge to the east of the study area. The highest concentration storms' back-trajectories display the lowest heights above the ground. Given their southwestern origin, these storms travel upslope along the seasonally dry river beds of the Gila River and its tributaries. Weaker dust storms originate over a wider area with a shift to a southerly direction. Such origination indicates that weaker dust storms are traveling downslope through the washes and channels of the dry Santa Cruz River. As dust concentrations drop, storm direction drifts east and dust height is suspended higher. This paper highlights the spatial variations in central Arizona dust storms, showing the likeliest paths of the strongest events and assists in identifying aeolian dust origins. • Identification of source regions of dust storms impacting the central Sonoran Desert located in the Arizona region of the Southwestern United States. • Use of the HYSPLIT back trajectory model. • Most large dust storms impacting central Arizona have a southwestern origin, having traveled upslope along the normally-dry Gila River and its tributaries. [ABSTRACT FROM AUTHOR]

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The article discusses an analysis of the damage and mortality of the freeze affected plants at the Boyce Thompson Arboretum in Arizona following a freeze event in February 2011. To describe the correlations for the geographic pattern of damage, base map was created and global positioning system (GPS) survey was made to collect precision elevation data. Plant damage was rated using a visible scale ranging from light to heavy. The project found negative association between damage and altitude.

Abstract: Though there is no known meteorological cause for weekly cycling of environmental variables, weekly cycles have been discovered at local to global scales, particularly in areas affected by human urbanization. To uncover such cycles in Phoenix, AZ, and to highlight possible mechanisms for their existence, data from several public domain sources were collected and analyzed for cycles in three categories of variables: meteorological, pollution, and human activity measured as vehicle traffic flows. Results indicated that many meteorological and pollution variables do exhibit weekly periodicity and that these cycles are likely due to the weekly pattern of human traffic flows. Atmospheric concentrations of O3 and NO X gases exhibit a high degree of negative correlation, supporting recent research that suggests anthropogenic NO X gases are effective scavengers of ozone in urban cores. Results further suggest that vehicle-generated NO X gases may be a significant generator of atmospheric nitrate particulates. Finally, both traffic flow and NO X gas concentrations display a strong correlation with wind speed in the urban core, though this study does not speculate on a mechanism for this relationship. [Copyright &y& Elsevier]

In approximately half of Arizona's summer season (June-September) mesoscale convective systems evolve into mesoscale convective vortices (MCVs). Analysis of satellite imagery identified MCVs in Arizona over the period 1991-2000, and local and regional rawinsonde data discriminated conditions conducive for MCV development. These results indicate that MCVs are more likely to form from convective systems when the local and regional environments are characterized by relative stability in the 850-700-hPa layer and moderate wind shear in the 500-200-hPa layer. These characteristics are similar to results reported for MCV development in the central United States. [ABSTRACT FROM AUTHOR]

Explains the effects of urbanization on the local weather patterns in Phoenix, Arizona. Rate of population growth in the area; Increase in volume of smog over the city; Increase in local temperatures due to the development of an urban heat island; Perception of increased humidity among local residents; Factors driving increasing temperatures in the Phoenix's desert environment; Potential impact of increasing weather stress on future planning and development.

Maricopa County, Arizona, anchor to the fastest growing megapolitan area in the United States, is located in a hot desert climate where extreme temperatures are associated with elevated risk of mortality. Continued urbanization in the region will impact atmospheric temperatures and, as a result, potentially affect human health. We aimed to quantify the number of excess deaths attributable to heat in Maricopa County based on three future urbanization and adaptation scenarios and multiple exposure variables. Two scenarios (low and high growth projections) represent the maximum possible uncertainty range associated with urbanization in central Arizona, and a third represents the adaptation of high-albedo cool roof technology. Using a Poisson regression model, we related temperature to mortality using data spanning 1983-2007. Regional climate model simulations based on 2050-projected urbanization scenarios for Maricopa County generated distributions of temperature change, and from these predicted changes future excess heat-related mortality was estimated. Subject to urbanization scenario and exposure variable utilized, projections of heat-related mortality ranged from a decrease of 46 deaths per year (-95%) to an increase of 339 deaths per year (+359%). Projections based on minimum temperature showed the greatest increase for all expansion and adaptation scenarios and were substantially higher than those for daily mean temperature. Projections based on maximum temperature were largely associated with declining mortality. Low-growth and adaptation scenarios led to the smallest increase in predicted heat-related mortality based on mean temperature projections. Use of only one exposure variable to project future heat-related deaths may therefore be misrepresentative in terms of direction of change and magnitude of effects. Because urbanization-induced impacts can vary across the diurnal cycle, projections of heat-related health outcomes that do not consider place-based, time-varying urban heat island effects are neglecting essential elements for policy relevant decision-making., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Hourly atmospheric carbon dioxide (CO2) concentration measurements are available from 1996 to present for a suburban site within the growing metropolitan area of Kuwait City. Analyses of this record reveal (a) an annual cycle with highest values in February and lowest values in September reflecting the growth and decay of vegetation in the Northern Hemisphere as well as fluctuations in motor traffic, (b) a weekly cycle with highest values during the weekdays and lowest values during weekends, and (c) a diurnal cycle with highest values after sunset when the local atmosphere becomes more stable following vehicular emission of CO2 throughout the day and lowest values in late afternoon following several hours of relatively unstable conditions. During the daytime, CO2 concentrations are related to wind direction, with westerly winds (coming from the desert) promoting lowest CO2 concentrations. At night, lowest CO2 levels are associated with higher wind speeds and winds from the north. The findings from the Kuwait City area, particularly when contrasted with the situation in Phoenix, further our understanding of the dynamics of CO2 levels in urban environments.