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Abstract:The urban heat island (UHI) phenomenon is a significant worldwide problem caused by rapid population growth and associated urbanization. The UHI effect exacerbates heat waves during the summer, increases energy and water consumption, and causes the high risk of heat-related morbidity and mortality. UHI mitigation efforts have increasingly relied on wisely designing the urban residential environment such as using high albedo rooftops, green rooftops, and planting trees and shrubs to provide canopy coverage and shading. Thus, strategically designed residential rooftops and their surrounding landscaping have the potential to translate into significant energy, long-term cost savings, and health benefits. Rooftop albedo, material, color, area, slope, height, aspect and nearby landscaping are factors that potentially contribute. To extract, derive, and analyze these rooftop parameters and outdoor landscaping information, high resolution optical satellite imagery, LIDAR (light detection and ranging) point clouds and thermal imagery are necessary. Using data from the City of Tempe AZ (a 2010 population of 160,000 people), we extracted residential rooftop footprints and rooftop configuration parameters from airborne LIDAR point clouds and QuickBird satellite imagery (2.4 m spatial resolution imagery). Those parameters were analyzed against surface temperature data from the MODIS/ASTER airborne simulator (MASTER). MASTER images provided fine resolution (7 m) surface temperature data for residential areas during daytime and night time. Utilizing these data, ordinary least squares (OLS) regression was used to evaluate the relationships between residential building OPEN ACCESSRemote Sens. 2015, 7 12136 rooftops and their surface temperature in urban environment. The results showed that daytime rooftop temperature was closely related to rooftop spectral attributes, aspect, slope, and surrounding trees. Night time temperature was only influenced by rooftop spectral attributes and slope.

Shade provided by trees, shrubs and other vegetation serves as a natural umbrella to mitigate insolation absorbed by features of the urban environment, especially building structures. For a desert community, tree shade is a valuable asset, contributing to energy conservation efforts, improving home values, enabling cost savings, and promoting enhanced health and well-being. Therefore, maximizing tree shade coverage is an important component in creating an eco-friendly and sustainable urban environment. Strategic placement of trees enhances tree shade coverage of buildings. This paper details an optimization method to simultaneously maximize tree shade coverage on building facades and open structures and to minimize shade coverage on building rooftops in a 3-dimensional environment. This method integrates geographic information systems and spatial optimization approaches for placing trees that provide the greatest potential benefit to a building. A residential area in Tempe, Arizona is utilized to demonstrate the capabilities of the method. The optimization results show that two trees can provide up to 22.20 m 2 shade coverage at 12:00 across a 54 m 2 south-facing façade. This research offers a method to help homeowners, urban planners, and policy makers to quantitatively evaluate shade coverage from trees for building structures in a residential environment.

Urban green infrastructure, especially shade trees, offers benefits to the urban residential environment by mitigating direct incoming solar radiation on building facades, particularly in hot settings. Understanding the impact of different tree locations and arrangements around residential properties has the potential to maximize cooling and can ultimately guide urban planners, designers, and homeowners on how to create the most sustainable urban environment. This research measures the cooling effect of tree shade on building facades through an outdoor urban physical scale model. The physical scale model is a simulated neighborhood consisting of an array of concrete cubes to represent houses with identical artificial trees. We tested and compared 10 different tree densities, locations, and arrangement scenarios in the physical scale model. The experimental results show that a single tree located at the southeast of the building can provide up to 2.3 • C hourly cooling benefits to east facade of the building. A two-tree cluster arrangement provides more cooling benefits (up to 6.6 • C hourly cooling benefits to the central facade) when trees are located near the south and southeast sides of the building. The research results confirm the cooling benefits of tree shade and the importance of wisely designing tree locations and arrangements in the built environment.

This study examines the effects of spatial clustering of urban land cover types on land surface temperature (LST). The potential impact of the background regional climate is also taken into consideration. To study this relationship, multiple cities, each representing a major Köppen climate region in the U.

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Disparities in healthy food accessibility have long been a public health concern. This study used the 2-step floating catchment area method to measure healthy food accessibility in East Baton Rouge Parish, Louisiana. The research creatively integrated the population with and without private vehicle to measure spatial accessibility. The overall disparities in healthy food access were firstly exhibited by a series of weighted average accessibility under different demographic groups. Furthermore, the relationships between healthy food access and other non-spatial socioeconomic characteristics were examined by ordinary least squares regression and geographically weighted regression to model the non-stationarity processes and understand the spatial variation of non-spatial socioeconomic factors. The research shows that the suburb areas near the periphery of the urbanized area have the highest healthy food access; within urbanized areas, the middle-south part fares better than the rest, while the rural areas suffer from poor healthy food access. The local pockets in central city score lower than the south of the study area despite higher density of population and number of food store. Socioeconomically disadvantaged population suffers from poorer accessibility because of relatively lower percentage of private vehicle ownership and they fare even worse in neighbourhoods without transit access. Such findings indicate that people are experiencing disparities in healthy food access not only because of 'where they are' but also 'who they are'. These results can help planners and policymakers scientifically design strategies to improve healthy food accessibility and eliminate inequalities.

A surface urban heat island (SUHI) effect is one of the most significant consequences of urbanization. Great progress has been made in evaluating the SUHI with cross-sectional studies performed in a number of cities across the globe. Few studies; however, have focused on the spatiotemporal changes in an area over a long period of time. Using multi-temporal remote sensing data sets, this study examined the spatiotemporal changes of the SUHI intensity in Las Vegas, Nevada, over a 15-year period from 2001 to 2016. We applied the geographically weighted regression (GWR) and advanced statistical approaches to investigating the SUHI variation in relation to several important biophysical indicators in the region. The results show that (1) Las Vegas had experienced a significant increase in the SUHI over the 15 years, (2) Vegetation and large and small water bodies in the city can help mitigate the SUHI effect and the cooling effect of vegetation had increased continuously from 2001 to 2016, (3) An urban heat sink (UHS) was identified in developed areas with low to moderate intensity, and (4) Increased surface temperatures were mainly driven by the urbanization-induced land conversions occurred over the 15 years. Findings from this study will inspire thoughts on practical guidelines for SUHI mitigation in a fast-growing desert city.