Sea Breeze Blowing into Urban Areas: Mitigation of the Urban Heat Island Phenomenon

2011 ◽  
pp. 11-32 ◽  
Author(s):  
Yoichi Kawamoto ◽  
Hiroshi Yoshikado ◽  
Ryozo Ooka ◽  
Hiroshi Hayami ◽  
Hong Huang ◽  
...  
Keyword(s):  
Urban Heat Island ◽  
Urban Areas ◽  
Sea Breeze ◽  
Heat Island ◽  
Urban Heat

scholarly journals Influence of Synoptic Sea-Breeze Fronts on the Urban Heat Island Intensity in Dallas–Fort Worth, Texas

2016 ◽  
Vol 144 (4) ◽  
pp. 1487-1507 ◽  
Author(s):  
Xiao-Ming Hu ◽  
Ming Xue
Keyword(s):  
Surface Temperature ◽  
Urban Heat Island ◽  
Urban Areas ◽  
Vertical Mixing ◽  
Sea Breeze ◽  
Fort Worth ◽  
Heat Island ◽  
Breeze Circulation ◽  
Near Surface ◽  
Urban Heat

Abstract When assessed using the difference between urban and rural air temperatures, the urban heat island (UHI) is most prominent during the nighttime. Typically, nocturnal UHI intensity is maintained throughout the night. The UHI intensity over Dallas–Fort Worth (DFW), Texas, however, experienced frequent “collapses” (sudden decreases) around midnight during August 2011, while the region was experiencing an intense heat wave. Observational and modeling studies were conducted to understand this unique phenomenon. Sea-breeze passage was found to be ultimately responsible for the collapses of the nocturnal UHI. Sea-breeze circulation developed along the coast of the Gulf of Mexico during the daytime. During the nighttime, the sea-breeze circulation was advected inland (as far as ~400 km) by the low-level jet-enhanced southerly flow, maintaining the characteristics of sea-breeze fronts, including the enhanced wind shear and vertical mixing. Ahead of the front, surface radiative cooling enhanced the near-surface temperature inversion in rural areas through the night with calm winds. During the frontal passage (around midnight at DFW), the enhanced vertical mixing at the leading edge of the fronts brought warmer air to the surface, leading to rural surface warming events. In contrast, urban effects led to a nearly neutral urban boundary layer. The enhanced mechanical mixing associated with sea-breeze fronts, therefore, did not increase urban surface temperature. The different responses to the sea-breeze frontal passages between rural (warming) and urban areas (no warming) led to the collapse of the UHI. The inland penetration of sea-breeze fronts at such large distances from the coast and their effects on UHI have not been documented in the literature.

scholarly journals Characterization of the subsurface urban heat island and its sources in the Milan city area, Italy

2021 ◽  
Author(s):  
Alberto Previati ◽  
Giovanni B. Crosta
Keyword(s):  
Urban Heat Island ◽  
Urban Areas ◽  
Heat Fluxes ◽  
Shallow Aquifer ◽  
Heat Island ◽  
Groundwater Temperature ◽  
City Area ◽  
Groundwater Environment ◽  
Urban Heat ◽  
The Impact

AbstractUrban areas are major contributors to the alteration of the local atmospheric and groundwater environment. The impact of such changes on the groundwater thermal regime is documented worldwide by elevated groundwater temperature in city centers with respect to the surrounding rural areas. This study investigates the subsurface urban heat island (SUHI) in the aquifers beneath the Milan city area in northern Italy, and assesses the natural and anthropogenic controls on groundwater temperatures within the urban area by analyzing groundwater head and temperature records acquired in the 2016–2020 period. This analysis demonstrates the occurrence of a SUHI with up to 3 °C intensity and reveals a correlation between the density of building/subsurface infrastructures and the mean annual groundwater temperature. Vertical heat fluxes to the aquifer are strongly related to the depth of the groundwater and the density of surface structures and infrastructures. The heat accumulation in the subsurface is reflected by a constant groundwater warming trend between +0.1 and + 0.4 °C/year that leads to a gain of 25 MJ/m2 of thermal energy per year in the shallow aquifer inside the SUHI area. Future monitoring of groundwater temperatures, combined with numerical modeling of coupled groundwater flow and heat transport, will be essential to reveal what this trend is controlled by and to make predictions on the lateral and vertical extent of the groundwater SUHI in the study area.

scholarly journals Biomimicry-Based Strategies for Urban Heat Island Mitigation: A Numerical Case Study under Tropical Climate

Biomimetics ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 48
Author(s):  
Kevin Araque ◽  
Paola Palacios ◽  
Dafni Mora ◽  
Miguel Chen Austin
Keyword(s):  
Thermal Comfort ◽  
Urban Heat Island ◽  
Urban Areas ◽  
Outdoor Thermal Comfort ◽  
Base Case ◽  
Heat Island ◽  
Urban Heat ◽  
Historical Heritage ◽  
Pet Index ◽  
Radiant Temperature

In recent years, demographic growth has caused cities to expand their urban areas, increasing the risk of overheating, creating insurmountable microclimatic conditions within the urban area, which is why studies have been carried out on the urban heat island effect (UHI) and its mitigation. Therefore, this research aims to evaluate the cooling potential in the application of strategies based on biomimicry for the microclimate in a historical heritage city of Panama. For this, three case studies (base case, case 1, and case 2) of outdoor thermal comfort were evaluated, in which the Envi-met software was used to emulate and evaluate the thermal performance of these strategies during March (highest temperature month) and October (rainier month). The strategies used were extracted from the contrast of zebra skin, human skin, evaporative cooling, and ant skin. The results showed a reduction of 2.8 °C in the air temperature at 11:00, the radiant temperature decreased by 2.2 °C, and the PET index managed to reduce the thermal comfort indicator among its categories. The importance of thinking based on biomimicry in sustainable strategies is concluded; although significant changes were obtained, high risks of discomfort persist due to the layout and proximity of the building.

scholarly journals Identifying Heat Health Risks in the Urban Areas of Western Australia (WA) – An Enhanced Heat Vulnerability Assessment

2019 ◽  
Vol 1 ◽  
pp. 1-1
Author(s):  
Qian Sun ◽  
Grace Yun ◽  
Ting Ling
Keyword(s):  
Risk Factors ◽  
Urban Heat Island ◽  
Health Risks ◽  
Western Australia ◽  
Urban Areas ◽  
Heat Island ◽  
Climate Change Research ◽  
Urban Heat ◽  
Heat Vulnerability ◽  
The Impact

<p><strong>Abstract.</strong> The impact of heat on health can be more significant in urban areas with more population and where the microclimate is often unintentionally modified to create the Urban Heat Island (UHI) effect. Extreme heat and UHI pose a risk to the health of vulnerable individuals, such as the elderly, the very young, and those need care. Vulnerability has become a central concept in climate change research and policy. To assess it, many studies have used equal weighted cumulative indices to aggregate multiple factors into a composite HVI (Heat Vulnerability Index) and analyse the differences and intensity across local areas and regions. However, the aggregation and equal weighting rationality, and the disregard of spatial correlation can result in inaccurate explanation on local vulnerabilities.</p><p>This study develops an enhanced index of population heat vulnerability (HVI) in Perth metropolitan area, Western Australia (WA), using environmental, demographic, and health-related risk factors for heat exposure, sensitivity and adaptive capability. Satellite derived urban heat island data and community profiles were integrated by a spatial risk assessment methodology to highlight potential heat health risk areas and build the foundations for mitigation and adaptation plans. Principal component analysis (PCA) was used to identify the key risk factors for heat vulnerability. Geographically weighted regression (GWR) were used to model the spatial relationships between temperature and other contributing factors to produce weights for calculating HVI. The index was finally mapped to produce a spatial representation of risk. The maps of spatial heat health vulnerability provide information to target heat-related health risks by aiding policy advisors, healthcare professionals, and ancillary services to develop heatwave preparedness plans at a local scale.</p>

The urban heat island of London, an empirical model

2019 ◽  
Vol 40 (3) ◽  
pp. 290-295 ◽  
Author(s):  
Geoff Levermore ◽  
John Parkinson
Keyword(s):  
Urban Heat Island ◽  
Empirical Model ◽  
Urban Areas ◽  
Urban Heat Island Intensity ◽  
Weather Data ◽  
Rural Site ◽  
City Centre ◽  
Heat Island ◽  
Data Set ◽  
Urban Heat

On top of climate change and its consequent temperature rises, urban areas have the added burden of the urban heat island (the urban area being warmer than the rural area especially at night under calm, cloud-free conditions). The urban heat island intensity (the difference between the rural air temperature and that in the city centre) can be as large as 10K for the major cities such as London. The urban heat island intensity, consequently, can have a significant effect on the sizing of heating, ventilating and air-conditioning plant and its energy consumption. At present, designers have access to empirical factors for design days only in June, July and August from the Chartered Institution of Building Services Engineers Guide. Or they can use the latest Design Summer Year which implicitly includes the urban heat island intensity. However, the empirical model discussed in this paper allows the designer to add on the hourly urban heat island intensity for central London to any recent year’s hourly weather data set from London Heathrow or Bracknell, a more rural site. The model is similar to one for Manchester, suggesting that the model may well be of application to other UK cities. Practical applications: Most buildings that building services engineers and other building designers are involved with are in urban or city centres. However, the weather data for their designs are based on near-rural weather data, which does not include the urban heat island effect. This paper describes the urban heat island effects that a designer needs to consider and the adjustments that can be made, related to London.

Emergence of opposite trends in daytime and night-time urban heat island intensities in England

2020 ◽  
Author(s):  
Eunice Lo ◽  
Dann Mitchell ◽  
Sylvia Bohnenstengel ◽  
Mat Collins ◽  
Ed Hawkins ◽  
...  
Keyword(s):  
Urban Heat Island ◽  
Urban Areas ◽  
Urban Land Use ◽  
Urban Heat Islands ◽  
Urban Heat Island Effect ◽  
Heat Island ◽  
Night Time ◽  
Heat Islands ◽  
Island Effect ◽  
Urban Heat

&lt;p&gt;Urban environments are known to be warmer than their sub-urban or rural surroundings, particularly at night. In summer, urban heat islands exacerbate the occurrence of extreme heat events, posing health risks to urban residents. In the UK where 90% of the population is projected to live in urban areas by 2050, projecting changes in urban heat islands in a warming climate is essential to adaptation and urban planning.&lt;/p&gt;&lt;p&gt;With the use of the new UK Climate Projections (UKCP18) in which urban land use is constant, I will show that both summer urban and sub-urban temperatures are projected to increase in the 10 most populous built-up areas in England between 1980 and 2080. However, differential warming rates in urban and sub-urban areas, and during day and at night suggest a trend towards a reduced daytime urban heat island effect but an enhanced night-time urban heat island effect. These changes in urban heat islands have implications on thermal comfort and local atmospheric circulations that impact the dispersion of air pollutants. I will further demonstrate that the opposite trends in daytime and night-time urban heat island effects are projected to emerge from current variability in more than half of the studied cities below a global mean warming of 3&amp;#176;C above pre-industrial levels.&lt;/p&gt;

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