scholarly journals Assessing urban heat island impact on long-term trends of air temperatures in Ljubljana

Dela ◽  
2015 ◽  
pp. 41-59
Author(s):  
Darko Ogrin ◽  
Marko Krevs
Keyword(s):  
Urban Heat Island ◽  
Air Temperature ◽  
City Centre ◽  
Heat Island ◽  
Temperature Trends ◽  
Air Temperatures ◽  
Long Term Trends ◽  
Urban Heat ◽  
The Hill

The paper presents an assessment of urban heat island (UHI) impact on air temperature trends inLjubljana. The assessments are based on the comparison between the long-term air temperature trends inLjubljanaandZagreb. Meteorological station Zagreb-Grič operated on the hill in the city centre since its establishment in 1862, while theLjubljanastation changed its location several times. The analysed UHI effect on the measurements of air temperature inLjubljanagradually increased, especially after 1950.

scholarly journals Relating urban development and densification to temporary changes in the air temperature in Warsaw (Poland)

2020 ◽  
Vol 142 (1-2) ◽  
pp. 513-523
Author(s):  
Tomasz Rozbicki ◽  
Małgorzata Kleniewska ◽  
Katarzyna Rozbicka ◽  
Grzegorz Majewski ◽  
Dariusz Gołaszewski
Keyword(s):  
Air Temperature ◽  
Surface Energy Balance ◽  
Thermal Conditions ◽  
Active Surface ◽  
City Centre ◽  
Heat Island ◽  
Temperature Trends ◽  
Urban Heat ◽  
The City

Abstract The assessment of the influence of urbanisation effects on air temperature trends has been widely discussed in the literature. Urbanisation affects the urban active surface energy balance, resulting in the formation of urban heat island, also observed in the Warsaw conurbation. This article presents the diversity of long-term changes in air temperature at three Warsaw meteorological stations situated in the districts of Ursynów, Okęcie and Bielany, and demonstrates changes in thermal conditions during a long-term urbanisation process. Ursynów is the station where the changes of the surrounding area were most significant among the three analysed ones and the rise in the air temperature for this station was the greatest and it was observed from 7.5 °C in the years 1961–1970 to 8.5 °C in the years 2001–2010. The diversity of air temperature between the stations depends on their location. All of them are situated within the conurbation, at some distance from the city centre but the nature of their surroundings is different. The diversity applies to all annual characteristics of air temperature: its mean, mean maximum and mean minimum values.

scholarly journals Cool Pavement Strategies for Urban Heat Island Mitigation in Suburban Phoenix, Arizona

2019 ◽  
Vol 11 (16) ◽  
pp. 4452 ◽  
Author(s):  
Sushobhan Sen ◽  
Jeffery Roesler ◽  
Benjamin Ruddell ◽  
Ariane Middel
Keyword(s):  
Urban Heat Island ◽  
Air Temperature ◽  
Urban Areas ◽  
Meteorological Data ◽  
Heat Island ◽  
Land Use Patterns ◽  
Reflective Coating ◽  
Air Temperatures ◽  
Artificial Surfaces ◽  
Urban Heat

Urban areas are characterized by a large proportion of artificial surfaces, such as concrete and asphalt, which absorb and store more heat than natural vegetation, leading to the Urban Heat Island (UHI) effect. Cool pavements, walls, and roofs have been suggested as a solution to mitigate UHI, but their effectiveness depends on local land-use patterns and surrounding urban forms. Meteorological data was collected using a mobile platform in the Power Ranch community of Gilbert, Arizona in the Phoenix Metropolitan Area, a region that experiences harsh summer temperatures. The warmest hour recorded during data collection was 13 August 2015 at 5:00 p.m., with a far-field air temperature of about 42 ∘ C and a low wind speed of 0.45 m/s from East-Southeast (ESE). An uncoupled pavement-urban canyon Computational Fluid Dynamics (CFD) model was developed and validated to study the microclimate of the area. Five scenarios were studied to investigate the effects of different pavements on UHI, replacing all pavements with surfaces of progressively higher albedo: New asphalt concrete, typical concrete, reflective concrete, making only roofs and walls reflective, and finally replacing all artificial surfaces with a reflective coating. While new asphalt surfaces increased the surrounding 2 m air temperatures by up to 0.5 ∘ C, replacing aged asphalt with typical concrete with higher albedo did not significantly decrease it. Reflective concrete pavements decreased air temperature by 0.2–0.4 ∘ C and reflective roofs and walls by 0.4–0.7 ∘ C, while replacing all roofs, walls, and pavements with a reflective coating led to a more significant decrease, of up to 0.8–1.0 ∘ C. Residences downstream of major collector roads experienced a decreased air temperature at the higher end of these ranges. However, large areas of natural surfaces for this community had a significant effect on downstream air temperatures, which limits the UHI mitigation potential of these strategies.

Analysis of temperature trends and urban heat island in Madrid

2020 ◽  
Author(s):  
Gregorio Maqueda ◽  
Carlos Yagüe ◽  
Carlos Román-Cascón ◽  
Encarna Serrano ◽  
Jon Ander Arrillaga
Keyword(s):  
Urban Heat Island ◽  
Urban Areas ◽  
Surface Energy Budget ◽  
City Centre ◽  
Synoptic Situation ◽  
Heat Island ◽  
Temperature Trends ◽  
Measuring Period ◽  
Urban Heat ◽  
The City

<p>The temperature in the cities is affected by both global climate change and local changes due to human activities and the different land use compared to rural surroundings. These local changes, which modify the surface energy budget in urban areas, include the replacement of the natural surfaces by buildings and pavements and the heat of anthropogenic origin (heating, air conditioning, traffic). Madrid city (Spain) has a current population of near 3.3 million people and a larger metropolitan area reaching around 6.5 million people. Hence, it is affected by the phenomenon called urban heat island (UHI), which indicates that a higher temperature is found in the city compared with the surrounding rural areas. UHI is defined as the temperature difference between the urban observatory and the rural one and especially affects the minimum temperatures since urban areas cool down to a lesser extent than the neighbouring rural sites. Moreover, the intensity of the UHI is modulated by the meteorological conditions (wind, cloudiness, surface pressure, precipitation), highly associated with different synoptic situations. In this work, we use the Madrid-Retiro meteorological station as the urban one, which has regular and homogeneous data from the beginning of XX century; and the station at Barajas airport (12 km from the city centre) as well as other stations out of Madrid city (but within a range of 20 km from the city centre) as the rural stations. They all have a common measuring period from 1961 until present. The main objectives of the work are: 1) to identify temperature trends in the meteorological stations (both urban and rural); 2) to evaluate the intensity of the UHI for the different rural stations; 3) to apply a systematic and objective algorithm to classify each day in different categories (related to synoptic situation) that produce a different degree of UHI intensity; and, 4) to evaluate possible trends in the UHI intensity.</p>

scholarly journals Trend Analysis of Urban Heat Island Intensity According to Urban Area Change in Asian Mega Cities

2019 ◽  
Vol 12 (1) ◽  
pp. 112 ◽  
Author(s):  
Kyungil Lee ◽  
Yoonji Kim ◽  
Hyun Chan Sung ◽  
Jieun Ryu ◽  
Seong Woo Jeon
Keyword(s):  
Urban Heat Island ◽  
Urban Area ◽  
Anthropogenic Heat ◽  
Heat Island ◽  
Individual Factor ◽  
Long Term Trends ◽  
Urban Heat ◽  
Increasing Trends ◽  
Mega Cities

Urban heat island (UHI) is a phenomenon that occurs in cities worldwide. Therefore, there is an increasing need for studies on the changes in UHI intensity and long-term trends based on macroscopic characteristics related to urbanization. In this study, changes in seasonal UHI intensity based on urban area were analyzed for eight Asian mega cities from 1992–2012. The results indicate that the change in pattern of UHI intensity varies for different cities and seasons. UHI intensity increased as the urban area size increased. Furthermore, the dependency of UHI intensity on the economic situation was also demonstrated. With respect to the seasons, significantly increasing trends appeared during the summer. Moreover, depending on urban characteristics such as geography and climate, increasing trends appeared during other seasons. Population was also found to affect UHI intensity by generating anthropogenic heat; however, its effect as an individual factor appeared to be insignificant. This is a macroscale study that analyzes the effect of urban area size on UHI intensity. Future studies on urbanization factors and levels influencing the UHI intensity using higher resolution materials are required

scholarly journals Urban heat island of the Moscow megacity: the long-term trends and new approaches for monitoring and research based on crowdsourcing data

2020 ◽  
Vol 606 ◽  
pp. 012063
Author(s):  
M I Varentsov ◽  
P I Konstantinov ◽  
N V Shartova ◽  
T E Samsonov ◽  
P E Kargashin ◽  
...  
Keyword(s):  
Urban Heat Island ◽  
Heat Island ◽  
New Approaches ◽  
Long Term Trends ◽  
Urban Heat

scholarly journals Urban Heat Island in Mediterranean Coastal Cities: The Case of Bari (Italy)

Climate ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 79 ◽  
Author(s):  
Alessandra Martinelli ◽  
Dionysia-Denia Kolokotsa ◽  
Francesco Fiorito
Keyword(s):  
Urban Heat Island ◽  
Air Temperature ◽  
National Standard ◽  
Heat Island ◽  
Night Time ◽  
Local Climate ◽  
Sea Breezes ◽  
Pollution Levels ◽  
Air Temperatures ◽  
Urban Heat

In being aware that some factors (i.e. increasing pollution levels, Urban Heat Island (UHI), extreme climate events) threaten the quality of life in cities, this paper intends to study the Atmospheric UHI phenomenon in Bari, a Mediterranean coastal city in Southern Italy. An experimental investigation at the micro-scale was conducted to study and quantify the UHI effect by considering several spots in the city to understand how the urban and physical characteristics of these areas modify air temperatures and lead to different UHI configurations. Air temperature data provided by fixed weather stations were first compared to assess the UHI distribution and its daily, monthly, seasonal and annual intensity in five years (from 2014 to 2018) to draw local climate information, and then compared with the relevant national standard. The study has shown that urban characteristics are crucial to the way the UHI phenomenon manifests itself. UHI reaches its maximum intensity in summer and during night-time. The areas with higher density (station 2—Local Climate Zone (LCZ) 2) record high values of UHI intensity both during daytime (4.0 °C) and night-time (4.2 °C). Areas with lower density (station 3—LCZ 5) show high values of UHI during daytime (up to 4.8 °C) and lower values of UHI intensity during night-time (up to 2.8 °C). It has also been confirmed that sea breezes—particularly noticeable in the coastal area—can mitigate temperatures and change the configuration of the UHI. Finally, by analysing the frequency distribution of current and future weather scenarios, up to additional 4 °C of increase of urban air temperature is expected, further increasing the current treats to urban liveability.

scholarly journals The spatial variability of air temperature and nocturnal urban heat island intensity in the city of Brno, Czech Republic

2015 ◽  
Vol 23 (3) ◽  
pp. 8-16 ◽  
Author(s):  
Petr Dobrovolný ◽  
Lukáš Krahula
Keyword(s):  
Spatial Variability ◽  
Urban Heat Island ◽  
Air Temperature ◽  
Temperature Measurements ◽  
City Centre ◽  
Heat Island ◽  
Entire Study ◽  
Urban Heat ◽  
Mobile Measurements ◽  
The City

AbstractThis study seeks to quantify the effects of a number of factors on the nocturnal air temperature field in a medium-sized central European city located in complex terrain. The main data sources consist of mobile air temperature measurements and a geographical database. Temperature measurements were taken along several profiles through the city centre and were made under a clear sky with no advection. Altogether nine sets of detailed measurements, in all seasons, were assembled. Altitude, quantity of vegetation, density of buildings and the structure of the transportation (road) system were considered as explanatory variables. The result is that the normalized difference vegetation index (NDVI) and the density of buildings were the most important factors, each of them explaining a substantial part (more than 50%) of overall air temperature variability. Mobile measurements with NDVI values as a covariate were used for interpolation of air temperature for the entire study area. The spatial variability of nocturnal air temperature and UHI intensity in Brno is the main output presented. Air temperatures interpolated from mobile measurements and NDVI values indicate that the mean urban heat island (UHI) intensity in the early night in summer is at its highest (approximately 5 °C) in the city centre and decreases towards the suburban areas.

scholarly journals A High-Resolution Monitoring Approach of Canopy Urban Heat Island using Random Forest Model and Multi-platform Observations

2021 ◽  
Author(s):  
Shihan Chen ◽  
Yuanjian Yang ◽  
Fei Deng ◽  
Yanhao Zhang ◽  
Duanyang Liu ◽  
...  
Keyword(s):  
High Resolution ◽  
Random Forest ◽  
Urban Heat Island ◽  
Air Temperature ◽  
Anthropogenic Heat ◽  
Heat Island ◽  
Model Framework ◽  
Rapid Urbanization ◽  
Urban Heat ◽  
The City

Abstract. Due to rapid urbanization and intense human activities, the urban heat island (UHI) effect has become a more concerning climatic and environmental issue. A high spatial resolution canopy UHI monitoring method would help better understand the urban thermal environment. Taking the city of Nanjing in China as an example, we propose a method for evaluating canopy UHI intensity (CUHII) at high resolution by using remote sensing data and machine learning with a Random Forest (RF) model. Firstly, the observed environmental parameters [e.g., surface albedo, land use/land cover, impervious surface, and anthropogenic heat flux (AHF)] around densely distributed meteorological stations were extracted from satellite images. These parameters were used as independent variables to construct an RF model for predicting air temperature. The correlation coefficient between the predicted and observed air temperature in the test set was 0.73, and the average root-mean-square error was 0.72 °C. Then, the spatial distribution of CUHII was evaluated at 30-m resolution based on the output of the RF model. We found that wind speed was negatively correlated with CUHII, and wind direction was strongly correlated with the CUHII offset direction. The CUHII reduced with the distance to the city center, due to the de-creasing proportion of built-up areas and reduced AHF in the same direction. The RF model framework developed for real-time monitoring and assessment of high-resolution CUHII provides scientific support for studying the changes and causes of CUHII, as well as the spatial pattern of urban thermal environments.

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