scholarly journals Degree-hours and Degree-days in Coastal Mediterranean Cities, Patras and Kalamata, Greece

2021 ◽  
Vol 2 (4) ◽  
pp. 1-1
Author(s):  
Panagiotis Kyriakopoulos ◽  
◽  
Athanassios Giannopoulos ◽  
Yannis G. Caouris ◽  
Manolis Souliotis ◽  
...  
Keyword(s):  
Air Temperature ◽  
Rural Areas ◽  
Historical Data ◽  
Ambient Air ◽  
Heat Island ◽  
Degree Days ◽  
Heating And Cooling ◽  
Island Effect ◽  
Two Cities ◽  
Urban Heat

The hourly ambient air temperature information was analyzed for two Greek coastal Mediterranean cities: Patras (for the entire 2018 year) with ten urban and one rural stations, and Kalamata (for the entire 2019 and 2020 years) with eight urban and two rural stations. The heating and cooling Degree Hours (DH) and Degree Days (DD) were calculated, for base temperatures of 18 °C and 26 °C, respectively. The urban heating degree hours for the cities of Patras and Kalamata were observed to be 19.2% and 24%, respectively, lower than that of the rural areas. Similarly, the urban cooling degree hours for the two cities were 9% and 22% higher than that of rural areas. These findings indicate a distinct urban heat island effect in both the cities, with greater effects in Kalamata than in Patras. Following comparisons with historical data from reliable sources, it could be observed that summers are trending warmer and winters are trending milder.

scholarly journals Impact of urban heat island effect on the heating and cooling loads of residential buildings in Tianjin City, China

2020 ◽  
Vol 39 (8) ◽  
pp. 1296-1307
Author(s):  
Fanchao MENG ◽  
Guoyu REN ◽  
Jun GUO ◽  
Lei ZHANG ◽  
Ruixue ZHANG ◽  
...  
Keyword(s):  
Urban Heat Island ◽  
Residential Buildings ◽  
Urban Heat Island Effect ◽  
Heat Island ◽  
Heating And Cooling ◽  
Island Effect ◽  
Urban Heat ◽  
Tianjin City ◽  
Cooling Loads

scholarly journals The urban heat island effect is closely related to cicada density in metropolitan Seoul

2017 ◽  
Author(s):  
Hoa Q. Nguyen ◽  
Yuseob Kim ◽  
Yikweon Jang
Keyword(s):  
Urban Heat Island ◽  
Rural Areas ◽  
Urban Areas ◽  
Underlying Mechanism ◽  
Heat Island ◽  
Population Densities ◽  
Island Effect ◽  
Significant Difference ◽  
Order Of Magnitude ◽  
Urban Heat

Background. Cryptotympana atrata and Hyalessa fuscata are the most abundant cicada species in the Korean Peninsula, where their population densities are higher in urban areas than in rural ones. The urban heat island (UHI) effect, wherein human activities cause urban areas to be significantly warmer than surrounding rural areas, may underlie this difference. We predicted a positive relationship between the degrees of UHI in urban areas and population densities of C. atrata and H. fuscata. Methods. To test this prediction, we examined cicada population densities in three groups: those of high and low UHI areas within metropolitan Seoul, and suburban areas. Enumeration surveys of cicada exuviae were conducted from July to August, 2015. Results. C. atrata and H. fuscata constituted almost 30% and 70% of the cicada populations, respectively, collected across all sampling localities. No significant difference in species composition was observed, regardless of groups, but the densities of the two species were significantly higher in urban areas with high UHI than in other groups. Specifically, densities of C. atrata in high UHI areas were approximately seven and four times higher compared to those in low UHI and in suburban groups, respectively. The order of magnitude was greater in H. fuscata, where densities in high UHI group were respectively 22 and six times higher than those in low UHI and in suburban groups. Discussion. These results suggest that the UHI effect may be closely linked to high cicada densities in metropolitan Seoul, although the underlying mechanism for this remains unclear.

Reduction Effects of Urban Heat Island by Water-Retentive Pavement

2012 ◽  
Vol 724 ◽  
pp. 147-150 ◽  
Author(s):  
Ree Ho Kim ◽  
Jong Bin Park ◽  
Jung Soo Mun ◽  
Jung Hun Lee
Keyword(s):  
Surface Temperature ◽  
Urban Heat Island ◽  
Air Temperature ◽  
Asphalt Pavement ◽  
Sensible Heat Flux ◽  
Heat Island ◽  
Sensible Heat ◽  
Summer Period ◽  
Island Effect ◽  
Urban Heat

Recently, increasing of impervious surface as concrete or asphalt pavement with urban development brought increasing of air temperature in city. So many researchers have explored ways to reduce the urban heat island effect and water-retentive or water absorbing pavements have been found to be very effective. In this study, to evaluate the reduction effects of urban heat reduction of water-retentive pavement, surface temperature of pavement, air temperature, wind speed and albedo were measured for 3 years (2008~2010, summer period). And the intensity of sensible heat flux was calculated to estimate a influence on air temperature. Experimental results indicated that water-retentive was effective to reduction of air temperature by decreasing of surface temperature of pavement compare to other pavements. This is showed that water-retentive pavement can be contributed to mitigation of urban heat island.

Analysis of heat wave features and urban heat island effect under climate change

2020 ◽  
Author(s):  
Ye Tian ◽  
Klaus Fraedrich ◽  
Feng Ma
Keyword(s):  
Climate Change ◽  
Urban Heat Island ◽  
Air Temperature ◽  
Extreme Events ◽  
Climate Models ◽  
Heat Waves ◽  
Urban Heat Island Effect ◽  
Heat Island ◽  
Island Effect ◽  
Urban Heat

<p>Extreme events such as heat waves occurred in urban have a large influence on human life due to population density. For urban areas, the urban heat island effect could further exacerbate the heat stress of heat waves. Meanwhile, the global climate change over the last few decades has changed the pattern and spatial distribution of local-scale extreme events. Commonly used climate models could capture broad-scale spatial changes in climate phenomena, but representing extreme events on local scales requires data with finer resolution. Here we present a deep learning based downscaling method to capture the localized near surface temperature features from climate models in the Coupled Model Intercomparison Project 6 (CMIP6) framework. The downscaling is based on super-resolution image processing methods which could build relationships between coarse and fine resolution. This downscaling framework will then be applied to future emission scenarios over the period 2030 to 2100. The influence of future climate change on the occurrence of heat waves in urban and its interaction with urban heat island effect for ten most densely populated cities in China are studied. The heat waves are defined based on air temperature and the urban heat island is measured by the urban-rural difference in 2m-height air temperature. Improvements in data resolution enhanced the utility for assessing the surface air temperature record. Comparisons of urban heat waves from multiple climate models suggest that near-surface temperature trends and heat island effects are greatly affected by global warming. High resolution climate data offer the potential for further assessment of worldwide urban warming influences.</p>

scholarly journals Evaluating the Effectiveness of Mitigation Options on Heat Stress for Sydney, Australia

2018 ◽  
Vol 57 (2) ◽  
pp. 209-220 ◽  
Author(s):  
Shaoxiu Ma ◽  
Andy Pitman ◽  
Jiachuan Yang ◽  
Claire Carouge ◽  
Jason P. Evans ◽  
...  
Keyword(s):  
Heat Stress ◽  
Urban Heat Island ◽  
Air Temperature ◽  
Ambient Air ◽  
Mitigation Strategies ◽  
Heat Island ◽  
Human Thermal Comfort ◽  
Ambient Air Temperature ◽  
Populations At Risk ◽  
Urban Heat

AbstractGlobal warming, in combination with the urban heat island effect, is increasing the temperature in cities. These changes increase the risk of heat stress for millions of city dwellers. Given the large populations at risk, a variety of mitigation strategies have been proposed to cool cities—including strategies that aim to reduce the ambient air temperature. This paper uses common heat stress metrics to evaluate the performance of several urban heat island mitigation strategies. The authors found that cooling via reducing net radiation or increasing irrigated vegetation in parks or on green roofs did reduce ambient air temperature. However, a lower air temperature did not necessarily lead to less heat stress because both temperature and humidity are important factors in determining human thermal comfort. Specifically, cooling the surface via evaporation through the use of irrigation increased humidity—consequently, the net impact on human comfort of any cooling was negligible. This result suggests that urban cooling strategies must aim to reduce ambient air temperatures without increasing humidity, for example via the deployment of solar panels over roofs or via cool roofs utilizing high albedos, in order to combat human heat stress in the urban environment.

scholarly journals Retrofitting solutions for a campus building to mitigate urban heat island in a hot humid climate

2021 ◽  
Vol 2042 (1) ◽  
pp. 012062
Author(s):  
Vajreshwari Patil ◽  
Maite Bizcarguenaga ◽  
Katherine Lieberknecht ◽  
Juliana Felkner
Keyword(s):  
Surface Temperature ◽  
Urban Heat Island ◽  
Air Temperature ◽  
Ambient Air ◽  
Cooling Effect ◽  
Heat Island ◽  
Humid Climate ◽  
Temperature Reduction ◽  
Urban Heat ◽  
Hot Humid Climate

Abstract In this study we examine the summer cooling effects of trees and green facades on reducing urban heat island effects. Using ENVI-met model simulations, we investigate the influence of added greenery on the surface and ambient air temperature and its role on air fluctuations in the hot humid climate of Austin, TX, at pedestrian height. Under the specific conditions considered in this model, the results show the combination of trees and green facades has a greater cooling effect. Added greenery to the building mostly impacts the building's surface temperature during the hottest hours of the day, registering a maximum surface temperature reduction of 20.33°C. Simulations also show a maximum overall potential air temperature reduction of 0.54°C, and a maximum potential air temperature cooling effect near the building of 0.91°C. Future research should be conducted to address this study's limitations. Nevertheless, these findings can provide architects, designers, planners, and policymakers with a better understanding of the many benefits trees and green facades have, and provide them with the necessary tools to implement new solutions across sectors and scales to reduce the impacts urban areas have on the environment and provide a better living for all.

scholarly journals Moderation of Summertime Heat Island Phenomena via Modification of the Urban Form in the Tokyo Metropolitan Area

2014 ◽  
Vol 53 (8) ◽  
pp. 1886-1900 ◽  
Author(s):  
Sachiho A. Adachi ◽  
Fujio Kimura ◽  
Hiroyuki Kusaka ◽  
Michael G. Duda ◽  
Yoshiki Yamagata ◽  
...  
Keyword(s):  
Urban Heat Island ◽  
Air Temperature ◽  
Metropolitan Area ◽  
Urban Form ◽  
Surface Air Temperature ◽  
Heat Island ◽  
Compact City ◽  
Tokyo Metropolitan Area ◽  
Island Effect ◽  
Urban Heat

AbstractThis study investigated the moderation of the urban heat island via changes in the urban form in the Tokyo metropolitan area (TMA). Two urban scenarios with the same population as that of the current urban form were used for sensitivity experiments: the dispersed-city and compact-city scenarios. Numerical experiments using the two urban scenarios as well as an experiment using the current urban form were conducted using a regional climate model coupled with a single-layer urban canopy model. The averaged nighttime surface air temperature in TMA increased by ~0.34°C in the dispersed-city scenario and decreased by ~0.1°C in the compact-city scenario. Therefore, the compact-city scenario had significant potential for moderating the mean areal heat-island effect in the entire TMA. Alternatively, in the central part of the TMA, these two urban-form scenarios produced opposite effects on the surface air temperature; that is, severe thermal conditions worsened further in the compact-city scenario because of the denser population. This result suggests that the compact-city form is not always appropriate for moderation of the urban-heat-island effect. This scenario would need to combine with other mitigation strategies, such as the additional greening of urban areas, especially in the central area. This study suggests that it is important to design a plan to adapt to higher urban temperatures, which are likely to ensue from future global warming and the urban heat island, from several perspectives; that is, designs should take into account not only climatological aspects but also impacts on urban inhabitants.

scholarly journals Numerical Simulation Analysis of the Impact of Urbanization on an Extreme Precipitation Event over Beijing–Tianjin–Hebei, China

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 945
Author(s):  
Jing Zhang ◽  
Yu-shu Zhou ◽  
Xin-yong Shen
Keyword(s):  
Surface Water ◽  
Extreme Precipitation ◽  
Upward Movement ◽  
Heat Island ◽  
Island Effect ◽  
Two Cities ◽  
Urban Heat ◽  
Impact Of Urbanization ◽  
The Impact ◽  
Bth Region

In this study, an extreme rainstorm that occurred in the Beijing–Tianjin–Hebei (BTH) region in China on 19–20 July 2016 is simulated and analyzed using the Weather Research and Forecasting model, coupled with a multilayer urban canopy scheme, to reveal the impact of urbanization on the extreme precipitation process in the region. The results show that the urban heat island effect (that is, surface warming and an increased near-ground sensible heat flux, which leads to increased vertical motion and atmospheric instability layer strengthening) plays a dominant role in the urban modification of rainfall during the early stages of urbanization, resulting in an increase of 6–10 mm in average hourly precipitation in urban and downwind areas. With the further development of urbanization in the BTH region, particularly in the big cities of Beijing and Tianjin, the large-scale expansion of the urban surface reduces the surface moisture, the evaporation of surface water from the ground, and the height of the atmospheric boundary layer, leading to an urban dry island effect brought about by the lack of near-surface water vapor, which inhibits an increase in precipitation. The positive effect of the urban heat island on precipitation was offset by the urban dry island effect, so the increase in precipitation in the urban areas was not obvious, but an increased range of 8–10 mm was noted. The existence of large cities changes the position of the strong upward movement of air, and convective upward movement is more likely to occur between the suburbs. With the further expansion of the underlying surface of the adjacent cities of Beijing and Tianjin, the upward movement between the two cities coincides, leading to an obvious increase in precipitation between the two cities.

scholarly journals Transformation of Urban Surfaces and Heat Islands in Nanjing during 1984–2018

2020 ◽  
Vol 12 (16) ◽  
pp. 6521
Author(s):  
Yanxia Li ◽  
Xinkai Zhang ◽  
Sijie Zhu ◽  
Xiaoyu Wang ◽  
Yongdong Lu ◽  
...  
Keyword(s):  
Urban Heat Island ◽  
Rural Areas ◽  
Land Surface ◽  
Remote Sensing Data ◽  
Urban Heat Island Effect ◽  
Heat Island ◽  
Heat Islands ◽  
Island Effect ◽  
Urban Heat ◽  
The Many

One of the many consequences of urbanization is the expansion of cities into rural areas, which leads to the transformation of lands from natural surfaces to developed surfaces. It is widely considered an established fact that urbanization generally increases the heat island effect. The objective of this study is to understand the pattern of urban surface transformation in the city of Nanjing since 1980 and to find, if any, the correlation between such transformation and the urban heat island effect. The supervised classification technique was used to analyze the remote sensing data obtained from Landsat to identify the different kinds of underlying surfaces. Land surface temperatures were calculated using a subset of Landsat data. The correlation between the transformation of underlying surfaces and the heat island effect was established through analytical and statistical approaches. The results clearly show that the proportion of developed surfaces has been steadily rising in Nanjing in the past 30 years and that the urban heat island effect is positively correlated with the expansion of hard pavement and the deterioration of green surfaces and water bodies considering the general trend.

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