An alternative explanation of the semiarid urban area “oasis effect”

Abstract

.[1] This research evaluates the climatic summertime representation of the diurnal cycle of near-surface temperature using the Weather Research and Forecasting System (WRF) over the rapidly urbanizing and water-vulnerable Phoenix metropolitan area. A suite of monthly, high-resolution (2 km grid spacing) simulations are conducted during the month of July with both a contemporary landscape and a hypothetical presettlement scenario. WRF demonstrates excellent agreement in the representation of the daily to monthly diurnal cycle of near-surface temperatures, including the accurate simulation of maximum daytime temperature timing. Thermal sensitivity to anthropogenic land use and land cover change (LULCC), assessed via replacement of the modern-day landscape with natural shrubland, is small on the regional scale. The WRF-simulated characterization of the diurnal cycle, supported by previous observational analyses, illustrates two distinct and opposing impacts on the urbanized diurnal cycle of the Phoenix metro area, with evening and nighttime warming partially offset by daytime cooling. The simulated nighttime urban heat island (UHI) over this semiarid urban complex is explained by well-known mechanisms (slow release of heat from within the urban fabric stored during daytime and increased emission of longwave radiation from the urban canopy toward the surface). During daylight hours, the limited vegetation and dry semidesert region surrounding metro Phoenix warms at greater rates than the urban complex. Although prior work has suggested that daytime temperatures are lower within the urban complex owing to the addition of residential and agricultural irrigation (i.e., "oasis effect") we show that modification of Phoenix's surrounding environment to a biome more representative of temperate regions eliminates the daytime urban cooling. Our results indicate that surrounding environmental conditions, including land cover and availability of soil moisture, play a principal role in establishing the nature and evolution of the diurnal cycle of near-surface temperature for the greater Phoenix, Arizona, metropolitan area relative to its rural and undeveloped counterpart.Citation: Georgescu, M., M. Moustaoui, A. Mahalov, and J. Dudhia (2011), An alternative explanation of the semiarid urban area "oasis effect",

Remote sensing of the surface urban heat island and land architecture in Phoenix, Arizona: Combined effects of land composition and configuration and cadastral–demographic–economic factors

“…Georgescu et al, 2011;Zheng et al, 2014;Zhou et al, 2014), but differs from most of this research by demonstrating the strong role of land configuration as well. The implications of corpus of these works is that urban areas, especially those in warm desert climates, could ameliorate the SUHI effect and the UHI effect at large by attention to the design of neighborhoods and, perhaps, parcels of new developments and to the reshaping of existing neighborhoods.…”

“…The UHI of large cities has increased substantially since the middle of the 20th century (Akbari, Pomerantz, & Taha, 2001;Oke, 1976;Stone, 2007), with urban conglomerations generating modeled and observed changes in regional temperatures (Georgescu, Moustaoui, Mahalov, & Dudhia, 2011;He, Liu, Zhuang, Zhang, & Liu, 2007;Kalnay & Cai, 2003;Li, Wang, Shen, & Song, 2004). Extensively examined, the UHI draws increasing attention owing to its effects on energy and water consumption, human health, environmental (ecosystem) services, especially in the context of global warming (e.g.…”

Citywide Impacts of Cool Roof and Rooftop Solar Photovoltaic Deployment on Near-Surface Air Temperature and Cooling Energy Demand

“…Specifically, we characterize the diurnal cycle of near-surface air temperature and citywide air-conditioning electricity consumption for different coverage rates of largescale cool roof and rooftop solar photovoltaic deployment for the two major USA cities of Arizona: Phoenix and Tucson. Both Phoenix and Tucson exhibit an intense nocturnal UHI, but during the day, they can show oasis effect (e.g., Brazel et al 2000;Georgescu et al 2011). The outline of the article is as follows: methodology and numerical experiments are described in Sect.…”

Analytical study of land surface temperature with NDVI and NDBI using Landsat 8 OLI and TIRS data in Florence and Naples city, Italy

“…The UHI of big cities has increased gradually since the last few decades (Akbari, Pomerantz, & Taha, 2001;Oke, 1976;Stone, 2007) with urban concentrations generating modelled and observed changes in regional temperatures (Georgescu, Moustaoui, Mahalov, & Dudhia, 2011;He, Liu, Zhuang, Zhang, & Liu, 2007;Kalnay & Cai, 2003;Li, Wang, Shen, & Song, 2004). The relationship between landscape pattern and UHI becomes globally considerable (Chen, Yao, Sun, & Chen, 2014;Coseo & Larsen, 2014;Du et al, 2016a;Du, Xiong, Wang, & Guo, 2016b;Li, Song, Cao, Meng, & Wu, 2011;Peng, Xie, Liu, & Ma, 2016).…”