Geospatial Analysis of Urban Heat Island Effects and Tree Equity

In recent decades, Urban Heat Island Effects have become more pronounced and more widely examined. Despite great technological advances, our current societies still experience great spatial disparity in urban forest access. Urban Heat Island Effects are measurable phenomenon that are being experienced by the world’s most urbanized areas, including increased summer high temperatures and lower evapotranspiration from having impervious surfaces instead of vegetation and trees. Tree canopy cover is our natural mitigation tool that absorbs sunlight for photosynthesis, protects humans from incoming radiation, and releases cooling moisture into the air. Unfortunately, urban areas typically have low levels of vegetation. Vulnerable urban communities are lower-income areas of inner cities with less access to heat protection like air conditioners. This study uses mean evapotranspiration levels to assess the variability of urban heat island effects across the state of Tennessee. Results show that increased developed land surface cover in Tennessee creates measurable changes in atmospheric evapotranspiration. As a result, the mean evapotranspiration levels in areas with less tree vegetation are significantly lower than the surrounding forested areas. Central areas of urban cities in Tennessee had lower mean evapotranspiration recordings than surrounding areas with less development. This work demonstrates the need for increased tree canopy coverage.

Spatial and temporal analysis of urban heat island effect over Tiruchirappalli city using geospatial techniques

Alterations made to the natural ground surface and the anthropogenic activity elevate the surface and air temperature in the urban areas compared with the surrounding rural areas,known as urban heat island effect.Thermal remote sensors measure the radiation emitted by ground objects,which can be used to estimate the land surface temperature and are beneficial for studying urban heat island effects.The present study investigates the spatial and temporal variations in the effects of urban heat island over Tiruchirappalli city in India during the summer and winter seasons.The study also identifies hot spots and cold spots within the study area.In this study,a significant land surface temperature difference was observed between the urban and rural areas,predominantly at night,indicating the presence of urban heat island at night.These diurnal land surface temperature fluctuations are also detected seasonally,with a relatively higher temperature intensity during the summer.The trend line analysis shows that the mean land surface temperature of the study area is increasing at a rate of 0.166 K/decade with p less than 0.01.By using the spatial autocorrelation method with the urban heat island index as the key parameter,hot spots with a 99 percent confidence level and a 95 percent confidence level were found within the urban area.A hot spot with 95 and 90 percent confidence level was identified outside the urban area.This spike in temperature for a particular region in the rural area is due to industry and the associated built-up area.The study also identified cold spots with a 90 percent confidence level within the rural area.However,cold spots with a 95 and 99 percent confidence level were not identified within the study area.

Impact of the Urban Heat Island Effect on Ozone Pollution in Chengdu City,China

With the advancement of urbanization,the urban heat island effect and ozone pollution have become hot issues in urban research.The urban heat island effect can impact ozone conversion,but its mechanism of action is unclear.In this study,the effects of the urban heat island effect on ozone concentration in Chengdu City,China,were investigated by comparing the ozone concentration under different heat island levels with ozone data from March 2020 to February 2021 and the temperature and wind field data of ERA5-Land during the same period.The results showed that:1)regarding the distribution characteristics,the ozone concentration in Chengdu presented a‘high in summer and low in winter’distribution.The ozone concentration in summer(189.54µg/m^(3))was nearly twice that in winter(91.99µg/m^(3)),and the ozone diurnal variation presented a‘single peak and single valley’distribution,with a peak at 16:00.2)For the characteristics of the heat island effect,the heat island intensity in Chengdu was obviously higher in spring than in other seasons,and the diurnal variation showed a‘single peak and single valley’distribution,with the peak and trough values appearing at 9:00 and 17:00,respectively.Spatially,the eastern part of Chengdu was a heat island,while the western and northwestern parts were mostly cold island.3)The correlation analysis between heat island intensity and ozone concentration showed a significant positive correlation but with a 7–8 h time lag.Ambient air temperature was not the main factor affecting ozone concentration.The heat island effect impacts the ozone concentration in two ways:changing the local heat budget to promote ozone generation and forming local urban wind,which promotes ozone diffusion or accumulation and forms different areas of low and high ozone values.

Changing Characteristics of Urban Heat Island Effect in Weihai City

Based on the local climate zoning theory and the observation data of hourly temperature of 22 automatic weather stations from 2012 to 2021, K-means clustering algorithm was used to analyze the daily, monthly, seasonal, annual and spatial variation characteristics of urban heat island effect in Weihai City in the past 10 years. The results showed that in recent 10 years, the average urban heat island intensity was 1.24 ℃, showing a gradual weakening trend of -0.169 3 ℃/10 a;the summer average heat island intensity was 0.86 ℃, showing a gradual weakening trend of -0.047 5 ℃/10 a. The heat island intensity had obvious diurnal variation characteristics, that is, "it was weak in the day and strong at night". In terms of seasonal variation, heat island effect was the weakest in summer, stronger in spring and autumn, and the strongest in winter. The diurnal, seasonal and annual changes of heat island intensity showed a reverse trend to those of temperature. The high-value area of urban heat island was highly consistent with human residential activity areas and industrial and commercial intensive areas, and the extension trend of heat island intensity was the same as the direction of urban development and construction. The "cold island phenomenon" in some offshore areas was related to the geographical location, terrain and the southeast monsoon trend in summer. The adverse effects of urban heat island effect can be reduced by optimizing the types and distribution of vegetation communities, rationally planning and constructing urban water body, promoting green building materials and adjusting shape design, etc.

Effects of Climate and the Urban Heat Island Effect on Urban Tree Growth in Houston

The growing conditions of urban trees differ substantially from forest sites and are mainly characterized by small planting pits with less water, nutrient and aeration availability, high temperatures and radiation inputs as well as pollution and soil compaction. Especially, global warming can amplify the negative effects of urban microclimates on tree growth, health and well-being of citizens. To quantify the growth of urban trees influenced by the urban climate, ten urban tree species in four climate zones were assessed in an overarching worldwide dendrochronological study. The focus of this analysis was the species water oak (Quercus nigra L.) in Houston, Texas, USA. Similar to the overall growth trend, we found in urban trees, water oaks displayed an accelerated growth during the last decades. Moreover, water oaks in the city center grew better than the water oaks growing in the rural surroundings of Houston, though this trend was reversed with high age. Growth habitat (urban, suburban, rural and forest) significantly affected tree growth (p < 0.001) with urban trees growing faster than rural growing trees and forest trees, though a younger age of urban trees might influence the found growth patterns. Growing site in terms of cardinal direction did not markedly influence tree growth, which was more influenced by the prevalent climatic conditions of Houston and the urban climate. Higher temperatures, an extended growing season and eutrophication can cause an accelerated growth of trees in urban regions across, across all climatic zones. However, an accelerated growth rate can have negative consequences like quicker ageing and tree death resulting in higher costs for new plantings and tree management as well as the decrease in ecosystem services due to a lack of old trees providing greatest benefits for mitigating the negative effects of the urban climate.

Analysis on the Variation Characteristics of Temperature in Anqing City and Urban Heat Island Effect

[Objective] The aim was to analyse the variation characteristics of temperature in Anqing City and urban heat island effect.[Method] Based on the observation data of temperature from Anqing Station,other surrounding meteorological stations and local automatic meteorological stations in suburbs,the annual variation of temperature and regional consistency was analysed,then the abrupt change of annual average temperature was tested by Mann-Kendall test,finally the influences of urban heat island effect on temperature variation in Anqing Station were studied.[Result] Affected by station migration and urban construction,the annual average temperature increased significantly in Anqing Station from 1977 to 2009,and the rising was more prominent after the middle of the 1990s.Mann-Kendall test showed that the change of temperature in Anqing Station was obviously abrupt around 1993;because of the development of urbanization,average temperature in Anqing Station was 0.8 ℃ higher than that in suburbs,and the minimum temperature rose more remarkably.In addition,urban heat island effect was the strongest in spring,followed by summer and autumn,while it was the weakest in winter.[Conclusion] The effects of urbanization development on the temperature in Anqing City were understood through this research.

Predicting Surface Urban Heat Island in Meihekou City, China: A Combination Method of Monte Carlo and Random Forest

Given the rapid urbanization worldwide, Urban Heat Island(UHI) effect has been a severe issue limiting urban sustainability in both large and small cities. In order to study the spatial pattern of Surface urban heat island(SUHI) in China’s Meihekou City, a combination method of Monte Carlo and Random Forest Regression(MC-RFR) is developed to construct the relationship between landscape pattern indices and Land Surface Temperature(LST). In this method, Monte Carlo acceptance-rejection sampling was added to the bootstrap layer of RFR to ensure the sensitivity of RFR to outliners of SUHI effect. The SHUI in 2030 was predicted by using this MC-RFR and the modeled future landscape pattern by Cellular Automata and Markov combination model(CA-Markov). Results reveal that forestland can greatly alleviate the impact of SUHI effect, while reasonable construction of urban land can also slow down the rising trend of SUHI. MC-RFR performs better for characterizing the relationship between landscape pattern and LST than single RFR or Linear Regression model. By 2030, the overall SUHI effect of Meihekou will be greatly enhanced, and the center of urban development will gradually shift to the central and western regions of the city. We suggest that urban designer and managers should concentrate vegetation and disperse built-up land to weaken the SUHI in the construction of new urban areas for its sustainability.

Change in Urban Wetlands and Their Cold Island Effects in Response to Rapid Urbanization

The cold-island effect of urban wetlands has received increasing attention in recent years due to its important role in the alleviation of urban heat islands.Hangzhou,a representative rapidly urbanizing city with rich wetlands in China,was selected as a case study for researching the changes that the urban wetlands have undergone and their impact on the urban thermal environment.Land surface temperature(LST) was acquired from the thermal infrared data of Landsat 5 Thematic Mapper(TM) images in 1990,1995,2000,2006,and 2010,using the single-channel method.The results are as follows:1) considering the changes in land use,the urban wetlands located to the west of Hangzhou have decreased significantly during 1990–2010 because of rapid urbanization.In the Xixi Wetland,the change in land use was relatively small and most of the water body and vegetation were preserved.However,to the east of the Xixi Wetland,large areas of water body and vegetation have been replaced by built-up land as a result of the urbanization process;2) considering the change in LST,it was found from land surface temperature retrieval that the changing spatial pattern of the thermal field was highly correlated with land use changes.Low temperature regions of the eastern Xixi Wetland were gradually eroded by high temperature regions,and the centroid of the heat island in East Xixi was found to be constantly shifting westward.In addition,the difference in LST between the Xixi Wetland and East Xixi has increased;3) considering the impact factors for this area,land use structure and patch shape were found to have a significant impact on LST,shown by the results of multiple linear stepwise regressions.Increasing the size of the wetlands in urban planning is considered to be the most effective measure in alleviating the urban heat island effect.Moreover,reducing the spatial complexity of landscape patches also contributes to the alleviation of the urban heat island effect.

Characteristics of urban heat island effect in Lhasa City

This paper analyzes the Urban Heat Island （UHI） effect in Lhasa City of Tibet using meteorological observations, the Normalized Difference Vegetation Index （NDVI）, Land Surface Temperature （LST） data obtained from Earth Observing System/Moderate resolution Imaging Spectroradiometer （EOS/MODIS） information, and correlation and composite analyses. The results show： （1） Areas with high temperature are primarily located in the center of the city or nearby counties, while low temperature areas are in the suburbs of counties. The area with high temperature has expanded in recent years and some high-temperature centers have even migrated to certain other regions. （2） The UHI intensity tends to be stronger both in annual and seasonal variations, especially in winter. Also, LST is somewhat positively related to mean air temperature. （3） A negative correlation exists between the changes of LST and NDVI with the increase of vegetation from urban to rural areas in different seasons. （4） The UHI intensity is negatively correlated with precipitation while positively correlated with wind speed, and the relation between the UHI intensity and evaporation varies with the seasons, namely, the intensity is positively correlated with summer evaporation but negatively corre- lated with winter evaporation. （5） UHI intensity might be enhanced by intensified urbanization, wherein built-up areas expand, there is increased heat from human activity, and there is more artificial heat input to the atmosphere.

Characteristics of Interdecadal Climate Change and Its Heat Island Effect in Ziyang City in Recent 60 Years

Based on 60 years of climate data from three national-level stations in Ziyang City,the characteristics of interdecadal variations of temperature,humidity,precipitation and sunshine that were closely related to heat island effect were analyzed.The data of township regional stations were used for comparison.The results show that the heat island effect value of Ziyang was between 0.3 and 4.3℃.It was the highest in 2015,up to 4.3℃;the minimum 0.3℃ appeared in 2011.The average heat island strength in the past 10 years was 1.2℃,and the average heating rate was 0.12℃/a.Among the four seasons,the highest value of heat island effect was 3.2℃ in summer,while the lowest value was 1.2℃ in winter.The order of heat island value in various seasons is as follows:summer>autumn>spring>winter.

Inversion of Urban Heat Island Effect in Xi'an City

[Objective] The study aims at conducting the inversion of urban heat island effect in Xi＇an City. [Method] Based on the United States Landsat-7 ETM~ and TM data in different phases, the spatial distribution and changing trends of urban heat island effect in Xi＇an City were ana- lyzed, and some corresponding measures to relieve the heat island effect in Xran were put forward according to its spatial distribution and intensity changes. [ Result] Urban heat island effect was very obvious in Xi＇an City, that is, surface temperature of urban areas was distinctly higher than that of surrounding suburban areas, and the high-temperature region was akin to an island with a clear boundary. As the enlarging of Xi＇an City, the areas subjected to heat island effect expended toward the south and north especially. In addition, heat island effect of Lantian District became more prominent, so it should be paid more attention to. We suggest that some measures like improving urban vegetation coverage, reasonably planing urban buildings, reducing the discharge of man-made heat, preventing and controlling atmospheric pollution should be adopted to control urban heat island effect of Xi＇an City effectively. [ Concision] The study could offer theoretical references for the control of urban heat island effect and the im- provement of ecological environment in Xi＇an City.

The Role of Green Infrastructure in Mitigating the Urban Heat Island Effect

The accelerating urbanization process and intensifying climate change have exacerbated the urban heat island effect, threatening sustainable urban development. This study investigates the role of green infrastructure in mitigating urban heat island effects, its implementation challenges, and applications. Employing a system dynamics approach, the research models the relationships between green infrastructure, urban microclimate, and human well-being. Findings indicate that large, continuous green spaces, such as urban parks and green corridors, are most effective, potentially reducing surrounding temperatures by 1˚C - 4˚C. Green infrastructure also provides multiple ecosystem services, including improved air quality and increased biodiversity. However, its implementation faces challenges such as land resource limitations and financial constraints. To address these issues, the study proposes a performance-based planning method, emphasizing multifunctional design and cross-sectoral collaboration. Through analysis of international and Chinese urban case studies, best practices and lessons learned are summarized. The research demonstrates that successful strategies must be context-specific, integrating local conditions while emphasizing long-term planning and continuous optimization. This study provides a scientific basis for developing effective heat island mitigation strategies and climate adaptation plans, ultimately achieving sustainable urban development and improved living environments.

Research and Experience Reference on London’s Response to Climate Change in the Twenty-first Century

London’s approaches to tackling climate change after the 21st century are multifaceted and relatively systematic.The aim of this research paper is to analyse London’s actions in response to climate change and to draw out what valuable lessons London has for the world in terms of its response to climate change.This paper provides an in-depth analysis of London’s policies and actions on climate mitigation in the areas of“greenhouse gas emissions”and“energy infrastructure”,and climate adaptation actions in the areas of“city green belt and urban afforestation”,“UHI and thermal crisis management”and“water supply infrastructure and sustainable drainage”.It then examines the positive aspects of these actions to determine what London has to say about climate change to the rest of the world and other cities.This paper also discovers that to effectively mitigate and adapt to climate change,London has not only established carbon reduction targets,but also created a large academic research network,represented by the LCCP.At the same time,London has developed a scientific climate change adaptation planning framework(P2R2)that focuses on four key areas:Economic,environmental,health,and infrastructure sectors,and three types of risks:Flooding,heat,and water supply,and emphasizes the dynamics and flexibility of each adaptation strategy.

ANALYSIS OF THE IMPACT OF URBAN GROWTH ON THE TEMPERATURE FIELD IN GUANGZHOU

Based on the 1973 - 2003 temperature data of Guangzhou meteorological station and 1980 - 2000 temperature data of Foshan airport, the variations of urbanization effect on temperature of Pearl River Delta （PRD） and Guangzhou city were analyzed. It was found that the temperature has increased significantly due to the PRD＇s urbanization. During the last 20 years, Foshan airport＇s temperature has increased by 0.7℃, and the Guangzhou city＇s temperature increased by about 1.℃ during last 30 years. The heat island of Guangzhou city is obvious but has some differences from other big Chinese cities.

Characterizing the Urban Temperature Trend Using Seasonal Unit Root Analysis:Hong Kong from 1970 to 2015

This paper explores urban temperature in Hong Kong using long-term time series. In particular, the characterization of the urban temperature trend was investigated using the seasonal unit root analysis of monthly mean air temperature data over the period January 1970 to December 2013. The seasonal unit root test makes it possible to determine the stochastic trend of monthly temperatures using an autoregressive model. The test results showed that mean air temperature has increased by 0.169~ C （10 yr） - 1 over the past four decades. The model of monthly temperature obtained from the seasonal unit root analysis was able to explain 95.9% of the variance in the measured monthly data -- much higher than the variance explained by the ordinary least-squares model using annual mean air temperature data and other studies alike. The model accurately predicted monthly mean air temperatures between January 2014 and December 2015 with a root-mean-square percentage error of 4.2%. The correlation between the predicted and the measured monthly mean air temperatures was 0.989. By analyzing the monthly air temperatures recorded at an urban site and a rural site, it was found that the urban heat island effect led to the urban site being on average 0.865~C warmer than the rural site over the past two decades. Besides, the results of correlation analysis showed that the increase in annual mean air temperature was significantly associated with the increase in population, gross domestic product, urban land use, and energy use, with the R2 values ranging from 0.37 to 0.43.

A ＂Trojan＂ in Climatic Change： The Urban Effect

This paper sets out the preliminary results of an experimental research plan aimed at analysing the thermal processes inherent to the urbanisation effect. Although this effect is undeniable, the extent of its impact is a matter of controversy. The results obtained in this study show both the nature of the phenomenon and its considerable magnitude. Failure to take this process into account might seriously bias any analysis of thermal evolution, the cornerstone of the climate change hypothesis.

Urbanization affects plant flowering phenology and pollinator community:effects of water availability and land cover

Introduction:Climate change and urbanization have been shown to alter plant phenology.However,a mechanistic understanding of these changes in flowering phenology and associated pollinator communities is lacking.Thus,this study was designed to examine finer scale flowering phenological patterns and driving processes in an arid urban ecosystem.Specifically,we tested the effect of water availability and land cover type on the flowering phenology of brittlebush(Encelia farinosa)and investigated the arthropod pollinator community associated with brittlebush.Methods:The fieldwork was carried out as part of a larger community ecology experiment following a factorial nested design.We chose three land cover types,each of which had three replicates,resulting in a total of nine sites.For water availability manipulations,60 genetically different 5-gallon potted plants were placed on the ground within each site.Pan-trapping was used to collect potential pollinators.Results:Our results showed that water availability did not produce significant differences in flowering phenology.However,brittlebush planted in mesiscaped urban sites bloomed later,longer,and at a higher percentage than those planted in desert remnant sites and desert fringe sites.Furthermore,desert remnant sites were significantly lower in pollinator abundance than desert fringe sites.Pollinator richness varied over time in all land cover types.Conclusions:This study provides empirical evidence that land cover type,which is strongly correlated to temperature,is the primary cause for altered flowering phenology of brittlebush in the Phoenix area,although water availability may also be important.Moreover,land cover affects total abundance of bee pollinators.