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Yifan Fan, Yuguo Li, Xiaoxue Wang, and Franco Catalano

1. Introduction The urban heat island (UHI) effect refers to the phenomenon in which an urban area (both the air and the surfaces) is generally warmer than its rural surroundings. UHI is not only a thermal phenomenon but also a driving force for a buoyancy-induced urban breeze or circulation, especially under weak synoptic systems. The basic airflow circulation is shown in Fig. 1 using flow visualization from a water-tank model combined with a sketch. The dome circulation is characterized by

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Shiguang Miao, Fei Chen, Margaret A. LeMone, Mukul Tewari, Qingchun Li, and Yingchun Wang

1. Introduction Urbanization rapidly spreads all over the world, and markedly modifies local and regional atmospheric properties, especially planetary boundary layer (PBL) structure, by perturbing the wind, temperature, moisture, turbulence, and surface energy budget fields. The well-recognized urban heat island (UHI) phenomenon, characterized by a temperature contrast between a city and its surrounding rural areas, is one prominent urban effect and can affect urban airflow, atmospheric

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Ning Zhang and Yan Chen

. 2009 ), to the synoptic and global climate scales (e.g., Jin et al. 2005 ). The urban heat island (UHI) phenomenon, characterized by a higher temperature difference between cities and the surrounding rural areas, is among the most significant urban phenomena. UHIs have been observed worldwide, not only in megacities (e.g., Childs and Raman 2005 ; Fast et al. 2005 ; Gaffin et al. 2008 ; Malevich and Klink 2011 ) but also in medium-sized and small cities (e.g., Giovannini et al. 2011 ; N

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Ning Zhang, Yan Chen, Ling Luo, and Yongwei Wang

exchange between the ground surface and the atmosphere compared to natural landscapes. The changes in land surface energy budgets cause warm surface layers over cities and form the urban heat island (UHI) phenomenon. The UHI may exacerbate heat waves over urban areas due to the low vegetation cover and less evapotranspiration in cities; these impacts have been proven by both observations and numerical simulations ( Grimmond 2007 ; Sugawara et al. 2008 ; Basara et al. 2010 ; Zhou and Shepherd 2010

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Julia Hidalgo, Valéry Masson, and Luis Gimeno

1. Introduction The urban heat island (UHI) is defined as the excess of temperature frequently observed in a metropolitan area in comparison with the surrounding area. The UHI has a typical daily cycle ( Oke 1982 ): it increases during the late afternoon and reaches its maximum during the night (5–8 K for a medium-sized European city), decreasing after dawn and generally reaching a minimum value during the morning hours, when it is possible to reach negative values. After that, it starts to

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R. Bassett, P. J. Young, G. S. Blair, F. Samreen, and W. Simm

; McGrane 2016 ) and air quality ( Han et al. 2016 ), flooding ( Adeloye and Rustum 2011 ), and modification of the local climate ( Kalnay and Cai 2003 ). Socially, impacts include housing shortages, poverty, and poor living conditions ( Opoko and Oluwatayo 2014 ; Jiboye and Ogunshakin 2011 ). While one of the primary impacts of urbanization, the urban heat island (UHI) effect, has been extensively documented in tropical areas of Asia and South America ( Roth 2007 ; Santamouris 2015 ), little research

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K. Van Weverberg, K. De Ridder, and A. Van Rompaey

1. Introduction As many temperature recording stations across the world have been affected by a gradual expansion of neighboring cities during their recording history, a warming bias due to the development of the urban heat island (UHI) has entered these time series. Such artifacts hamper an accurate estimation of regional climate change. Although UHIs do not substantially influence temperatures on a global ( Houghton et al. 2001 ) or continental scale ( Peterson 2003 ), they do affect local

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Talmor Meir, Philip M. Orton, Julie Pullen, Teddy Holt, William T. Thompson, and Mark F. Arend

City has an area of 790 km 2 , a population of 8 million, and contains five boroughs that are all influenced by the marine coastal atmosphere. NYC lies at the center of a broader urban and suburban metropolitan region, with Long Island extending to the east and New Jersey and the city of Newark to the west and southwest. Both NJ and Long Island are bordered by the coastal waters of the Atlantic ( Fig. 1 ). NYC and its surrounding urbanized region generate a pronounced urban heat island (UHI) effect

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Sachiho A. Adachi, Fujio Kimura, Hiroyuki Kusaka, Michael G. Duda, Yoshiki Yamagata, Hajime Seya, Kumiko Nakamichi, and Toshinori Aoyagi

local urbanization and global warming due to the increased emission of anthropogenic greenhouse gases (e.g., Fujibe 2009 ). The frequency of hot summers, such as that of 2010, is projected to increase in Japan in the future because of global climate change ( Solomon et al. 2007 ; Japan Meteorological Agency 2005 ; Kusaka et al. 2012 ). Thus, countermeasures against hot humid summer conditions in the TMA are required. Moderation of the urban heat island is a potential method to improve

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Patrick Conry, Ashish Sharma, Mark J. Potosnak, Laura S. Leo, Edward Bensman, Jessica J. Hellmann, and Harindra J. S. Fernando

evapotranspiration (see appendix A for a list of acronyms used in this paper). The thermal and mechanical attributes of urban canopies lead to a range of phenomena. On the mesoscale, these include the urban heat island [UHI, or warm urban core relative to rural surroundings, especially at night; Oke (1978) ; Fernando et al. (2010) ], distorted synoptic and mesoscale (slope and valley, sea and lake breeze) winds ( Keeler and Kristovich 2012 ), and rainfall modification ( Niyogi et al. 2011 ). On the

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