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Heat Island (heat + island)
Kinds of Heat Island Selected AbstractsLong-term changes and regional differences in temperature and precipitation in the metropolitan area of HamburgINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 8 2010K. H. Schlünzen Abstract Climate changes and the urban climate of the ,green city' Hamburg and its metropolitan region are analyzed using observational data for temperature and precipitation. Values for Hamburg's synoptic site HH-Fuhlsbüttel start in 1891 and are used to determine climate changes. Additional data from up to 45 climate stations are used to analyze the different aspects of the regional climate and urban effects on the temperature [urban heat island (UHI)] and precipitation [urban precipitation impact (UPI)]. The analysis of the long-term data shows that the climate has already changed. Annual precipitation significantly increases ,0.8 mm/year when focusing on years 1891,2007 and ,1.3 mm/year for 1948,2007. Precipitation increases are largest in November through March and March as well as June for 1978,2007. For April and July of this period, a precipitation decrease is found. The precipitation distribution shows that moderate daily precipitation amounts (,10 mm/day) have increased by about 10% between 1948,1977 and 1978,2007. Precipitation amounts > 10 mm/day have increased by 20% in the same period. Average temperatures significantly increase by 0.07 K/decade (1891,2007), 0.19 K/decade (1948,2007), 0.6 K/decade (1978,2007) with largest significant increases in fall. For the UHI, it is found that the average temperature is higher up to 1.1 K in the densely build-up city area than outside. Values are about halved for more green urban areas but also depend on more local impacts. The minimum temperatures are up to 3 K higher and maximum temperatures slightly lower in the inner city than in the rural during summer. The winter temperatures are higher throughout the urban area. The UHI differences depend on wind speed; this dependence is best described by using the inverse square root of the wind speed. Classification using different wind directions shows that the precipitation is significantly higher (5,20%) for downwind of urban areas compared with the upwind side. Copyright © 2009 Royal Meteorological Society [source] Sensitivity study of the urban heat island intensity to urban characteristicsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 7 2008R. Hamdi Abstract A detailed urban surface exchange parameterization, implemented in a meso-scale atmospheric model, has been used to study the urban heat island (UHI) intensity during a summer period in the city of Basel, Switzerland. In this urban parameterization, the city is represented as a combination of three urban classes (road, roof and wall), characterized by the size of the street canyon and the building and is thus able to take into account the momentum sink over the entire height of the building, as well as the shadowing and the radiation trapping effects. A control experiment including all the urban parameters describing the city centre of Basel produced a canyon air temperature that compared well with observations. A series of experiments was then conducted in which successively each of the urban parameters characterizing the city centre was changed providing the basis for an assessment of its effect on UHI mitigation. Copyright © 2007 Royal Meteorological Society [source] Two decades of urban climate research: a review of turbulence, exchanges of energy and water, and the urban heat islandINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 1 2003A. John Arnfield Abstract Progress in urban climatology over the two decades since the first publication of the International Journal of Climatology is reviewed. It is emphasized that urban climatology during this period has benefited from conceptual advances made in microclimatology and boundary-layer climatology in general. The role of scale, heterogeneity, dynamic source areas for turbulent fluxes and the complexity introduced by the roughness sublayer over the tall, rigid roughness elements of cities is described. The diversity of urban heat islands, depending on the medium sensed and the sensing technique, is explained. The review focuses on two areas within urban climatology. First, it assesses advances in the study of selected urban climatic processes relating to urban atmospheric turbulence (including surface roughness) and exchange processes for energy and water, at scales of consideration ranging from individual facets of the urban environment, through streets and city blocks to neighbourhoods. Second, it explores the literature on the urban temperature field. The state of knowledge about urban heat islands around 1980 is described and work since then is assessed in terms of similarities to and contrasts with that situation. Finally, the main advances are summarized and recommendations for urban climate work in the future are made. Copyright © 2003 Royal Meteorological Society. [source] Simulation of the mean urban heat island using 2D surface parameters: empirical modelling, verification and extensionMETEOROLOGICAL APPLICATIONS, Issue 3 2009Bernadett Balázs Abstract The spatial distribution of the annual mean urban heat island (UHI) intensity was simulated applying empirical models based on datasets from urban areas of Szeged and Debrecen, using simple and easily determinable urban surface cover variables. These two cities are situated on the Alföld (Great Hungarian Plain) and have similar topographic and climatic conditions. Temperature field measurements were carried out, Landsat satellite images were evaluated, and then one- and multiple variable models were constructed using linear regression techniques. The selected multiple-parameter models were verified using independent datasets from three urban settlements. In order to obtain some impression of the mean UHI patterns in other cities with no temperature measurements available, the better model was extended to urban areas of four other cities situated in geographical environments similar to Szeged and Debrecen. The main shortcoming of typical empirical models, namely that they are often restricted to a specific location, is overcome by the obtained model since it is not entirely site but more region specific, and valid in a large and densely populated area with several settlements. Copyright © 2009 Royal Meteorological Society [source] The impact of urban areas on weatherTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 614 2006C. G. Collier Abstract The industrial revolution led to a rapid development of urban areas. This has continued unremittingly over the last 200 years or so. In most urban areas the surface properties are heterogeneous, which has significant implications for energy budgets, water budgets and weather phenomena within the part of the earth's atmosphere that humans live. In this paper I discuss the structure of the planetary boundary layer, confining our analysis to the region above the rooftops (canopy layer) up to around the level where clouds form. It is in this part of the atmosphere that most of the weather impacting our lives occurs, and where the buildings of our cities impact the weather. In this review, observations of the structure of the urban atmospheric boundary layer are discussed. In particular the use of Doppler lidar provides measurements above the canopy layer. The impact of high-rise buildings is considered. Urban morphology impacts energy fluxes and airflow leading to phenomena such as the urban heat island and convective rainfall initiation. I discuss in situ surface-based remote sensing and satellite measurements of these effects. Measurements have been used with simple and complex numerical models to understand the complexity and balance of the interactions involved. Cities have been found to be sometimes up to 10 degC warmer than the surrounding rural areas, and to cause large increases in rainfall amounts. However, there are situations in which urban aerosol may suppress precipitation. Although much progress has been made in understanding these impacts, our knowledge remains incomplete. These limitations are identified. As city living becomes even more the norm for large numbers of people, it is imperative that we ensure that urban effects on the weather are included in development plans for the built environment of the future. Copyright © 2006 Royal Meteorological Society [source] Impact of environmental flows on the daytime urban boundary layer structures over the Baltimore metropolitan regionATMOSPHERIC SCIENCE LETTERS, Issue 1 2010Yi-Xuan Shou Abstract The three-dimensional structures of the urban daytime boundary layer (UDBL) over Baltimore are examined using a coupled Weather Research and Forecast,Urban Canopy model. Results show the upward growth of the urban heat island (UHI) effects as the surface-based ,hot plumes' with pronounced rising motions and thermal gradients. The UDBL tends to exhibit different vertical structures and intensities, depending on the magnitude and direction of environmental flows with respect to urban morphometric distributions and its interaction with the circulations induced by differential land covers. They are determined by both the local UHI effects and the nonlocal advective processes. Copyright © 2010 Royal Meteorological Society [source] Two decades of urban climate research: a review of turbulence, exchanges of energy and water, and the urban heat islandINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 1 2003A. John Arnfield Abstract Progress in urban climatology over the two decades since the first publication of the International Journal of Climatology is reviewed. It is emphasized that urban climatology during this period has benefited from conceptual advances made in microclimatology and boundary-layer climatology in general. The role of scale, heterogeneity, dynamic source areas for turbulent fluxes and the complexity introduced by the roughness sublayer over the tall, rigid roughness elements of cities is described. The diversity of urban heat islands, depending on the medium sensed and the sensing technique, is explained. The review focuses on two areas within urban climatology. First, it assesses advances in the study of selected urban climatic processes relating to urban atmospheric turbulence (including surface roughness) and exchange processes for energy and water, at scales of consideration ranging from individual facets of the urban environment, through streets and city blocks to neighbourhoods. Second, it explores the literature on the urban temperature field. The state of knowledge about urban heat islands around 1980 is described and work since then is assessed in terms of similarities to and contrasts with that situation. Finally, the main advances are summarized and recommendations for urban climate work in the future are made. Copyright © 2003 Royal Meteorological Society. [source] | ||||||||||