scholarly journals Evaluating Bi-temporal Dynamics and Trend of Urbanization-induced Land Cover Temperature in Shanghai, China

2019 ◽  
Vol 1 ◽  
pp. 1-1
Author(s):  
Fei Liu ◽  
Yuji Murayama
Keyword(s):  
Land Cover ◽  
Rural Area ◽  
Land Surface ◽  
Temporal Dynamics ◽  
Thermal Environment ◽  
Impervious Surfaces ◽  
Land Utilization ◽  
Local Climate ◽  
Human System ◽  
Urban Thermal Environment

<p><strong>Abstract.</strong> In China today, massive land use/land cover change (LULCC) driven by urbanization has become a dominant phenomenon in the interactions between the human system and land surface. Drastic urbanization has changed land surface properties where a great deal of physical landscapes has been replaced by artificial buildings, and this evolution has brought about great potential risks and pressures physically and socially. In this study, taking the Shanghai metropolitan area (SMA) as the study area, we examine the spatiotemporal dynamics of temperature in urban land cover and explore the sustainable strategies for future development.</p><p>Shanghai, one of the Chinese gigantic cities, had the residential population of 24.15 million in 2015. The phenomena of urban heat island (UHI) in SMA have become prominent by the urbanization-related anthropic activities and increasing population. Until the present, a substantial number of investigations has been conducted in the Shanghai's thermal environment based on remote sensing data. However, the comprehensive assessments of urban thermal environment are not enough in Shanghai. This kind of research is expected to provide a significant paradigm for the exploration of a sustainable development of Chinese megacities, which examines the mechanism of the interactions between urban thermal environment and human system and addresses its adverse effect on the urban environment.</p><p>In this study, bi-temporal Landsat satellite data (Sep.2000 and Aug.2015) were used for the detection of LULCC and the estimation of land surface temperature (LST) in SMA. The LST was retrieved using the radiation transfer equation (RTE), and then normalized and graded in order to remove the influence of the seasonality and local climate characteristics. The spatiotemporal configuration and variation of urban thermal environment in SMA between 2000 and 2015 were synthetically monitored and evaluated through the analyses of the urban-rural gradient, gravity center change, spatial landscape pattern, and geographically weighted regression. Furthermore, the spatial determinants for the formation of UHI in SMA were identified in the analysis.</p><p>The results showed that (1) in 2000, the LST in the downtown of SMA was higher than that in the outskirts and rural area; (2) the extent of UHI in SMA was gradually expanding from 2000 to 2015 along the direction of urban growth, however, the UHI intensity in the downtown area was relatively declining due to the explosive increase of impervious surfaces in the suburban and rural area; (3) the spatiotemporal evolution of SMA's urban thermal environment was highly consistent with the track of LULCC, and greatly influenced by the spatial pattern and variation of urban landscape; (4) impervious surfaces obviously facilitated and strengthened the UHI effect, inversely, greenbelt and water space contributed to the mitigation and alleviation of the UHI effect; and (5) population convergence, industrial growth, dense land utilization, and urban development policies also affected the SMA's urban thermal environment.</p>

scholarly journals Impacts of Land Cover/Use on the Urban Thermal Environment: A Comparative Study of 10 Megacities in China

2020 ◽  
Vol 12 (2) ◽  
pp. 307 ◽  
Author(s):  
Fei Liu ◽  
Xinmin Zhang ◽  
Yuji Murayama ◽  
Takehiro Morimoto
Keyword(s):  
Land Cover ◽  
Surface Temperature ◽  
Land Surface Temperature ◽  
Rural Areas ◽  
Land Surface ◽  
Thermal Environment ◽  
Causal Mechanism ◽  
Impervious Surfaces ◽  
Rapid Urbanization ◽  
Urban Thermal Environment

Satellite-derived land surface temperature (LST) reveals the variations and impacts on the terrestrial thermal environment on a broad spatial scale. The drastic growth of urbanization-induced impervious surfaces and the urban population has generated a remarkably increasing influence on the urban thermal environment in China. This research was aimed to investigate land surface temperature (LST) intensity response to urban land cover/use by examining the thermal impact on urban settings in ten Chinese megacities (i.e., Beijing, Dongguan, Guangzhou, Hangzhou, Harbin, Nanjing, Shenyang, Suzhou, Tianjin, and Wuhan). Surface urban heat island (SUHI) footprints were scrutinized and compared by magnitude and extent. The causal mechanism among land cover composition (LCC), population, and SUHI was also identified. Spatial patterns of the thermal environments were identical to those of land cover/use. In addition, most impervious surface materials (greater than 81%) were labeled as heat sources, on the other hand, water and vegetation were functioned as heat sinks. More than 85% of heat budgets in Beijing and Guangzhou were generated from impervious surfaces. SUHI for all megacities showed spatially gradient decays between urban and surrounding rural areas; further, temperature peaks are not always dominant in the urban core, despite extremely dense impervious surfaces. The composition ratio of land cover (LCC%) negatively correlates with SUHI intensity (SUHII), whereas the population positively associates with SUHII. For all targeted megacities, land cover composition and population account for more than 63.9% of SUHI formation using geographically weighted regression. The findings can help optimize land cover/use to relieve pressure from rapid urbanization, maintain urban ecological balance, and meet the demands of sustainable urban growth.

scholarly journals Analysis of Seasonal Daytime Urban Thermal Environment Dynamics in a Tropical Coastal City Based on the Spatiotemporal Fusion Model

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Yuan Yao ◽  
Yiling Lu ◽  
Fang Zhang ◽  
Lulu Liu ◽  
Min Liao
Keyword(s):  
Land Cover ◽  
Landscape Metrics ◽  
Seasonal Variations ◽  
Land Surface ◽  
Thermal Environment ◽  
Fusion Model ◽  
Spatiotemporal Resolution ◽  
High Spatiotemporal Resolution ◽  
Urban Thermal Environment ◽  
The Relationship

This study investigated the seasonal variations of daytime urban thermal environment (UTE) based on land surface temperature (LST) in Shenzhen of 2015. The spatial and temporal adaptive reflectance fusion model (STARFM) was used for retrieving seasonal daytime LST at high spatiotemporal resolution by combining MODIS and HJ-1B LST data. Next, the relationship between the land cover and daytime in each season was examined. Finally, daytime LST patterns were classified, and the effects of seasonal variations of high-grade daytime LSTs were analyzed with landscape metrics. The results showed that (1) the STARFM is capable of generating seasonal daytime LST data at high spatiotemporal resolution. (2) Daytime LSTs were generally higher in the western parts of Shenzhen in spring and summer. (3) Daytime LST in each land cover type showed an increasing trend form winter to summer and decreased from summer to autumn. The highest and lowest daytime LSTs in each season were observed in ISAs and water bodies. (4) Landscape metrics provided a quantitative method for describing seasonal variations in daytime LSTs, and it was found that seasons influenced the intensity and extent of daytime LSTs in Shenzhen. These findings may be helpful for urban planners developing regional urban strategies to improve daytime urban thermal comfort conditions.

Remote Sensing-Based Approach to Identify the Influence of Land Use/Land Cover Change on the Urban Thermal Environment

2021 ◽  
pp. 217-240
Author(s):  
Abdulla-Al Kafy ◽  
Muhaiminul Islam ◽  
Soumik Sikdar ◽  
Tahera Jahan Ashrafi ◽  
Abdullah Al-Faisal ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Land Use ◽  
Land Cover ◽  
Land Cover Change ◽  
Thermal Environment ◽  
Land Use Land Cover ◽  
Urban Thermal Environment

scholarly journals Quantifying the Effects of Urban Form on Land Surface Temperature in Subtropical High-Density Urban Areas Using Machine Learning

2019 ◽  
Vol 11 (8) ◽  
pp. 959 ◽  
Author(s):  
Yanwei Sun ◽  
Chao Gao ◽  
Jialin Li ◽  
Run Wang ◽  
Jian Liu
Keyword(s):  
Surface Temperature ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Urban Form ◽  
Urban Areas ◽  
Thermal Environment ◽  
High Density ◽  
Cooling Effects ◽  
Urban Thermal Environment ◽  
The Impact

It is widely acknowledged that urban form significantly affects urban thermal environment, which is a key element to adapt and mitigate extreme high temperature weather in high-density urban areas. However, few studies have discussed the impact of physical urban form features on the land surface temperature (LST) from a perspective of comprehensive urban spatial structures. This study used the ordinary least-squares regression (OLS) and random forest regression (RF) to distinguish the relative contributions of urban form metrics on LST at three observation scales. Results of this study indicate that more than 90% of the LST variations were explained by selected urban form metrics using RF. Effects of the magnitude and direction of urban form metrics on LST varied with the changes of seasons and observation scales. Overall, building morphology and urban ecological infrastructure had dominant effects on LST variations in high-density urban centers. Urban green space and water bodies demonstrated stronger cooling effects, especially in summer. Building density (BD) exhibited significant positive effects on LST, whereas the floor area ratio (FAR) showed a negative influence on LST. The results can be applied to investigate and implement urban thermal environment mitigation planning for city managers and planners.

scholarly journals Effect of Land Cover Fractions on Changes in Surface Urban Heat Islands Using Landsat Time-Series Images

2019 ◽  
Vol 16 (6) ◽  
pp. 971 ◽  
Author(s):  
Tao Chen ◽  
Anchang Sun ◽  
Ruiqing Niu
Keyword(s):  
Land Cover ◽  
Urban Heat Island ◽  
Land Surface ◽  
Urban Heat Islands ◽  
Urban Heat Island Intensity ◽  
Heat Island ◽  
Impervious Surfaces ◽  
Heat Islands ◽  
Urban Heat ◽  
Surface Urban Heat Island

Man-made materials now cover a dominant proportion of urban areas, and such conditions not only change the absorption of solar radiation, but also the allocation of the solar radiation and cause the surface urban heat island effect, which is considered a serious problem associated with the deterioration of urban environments. Although numerous studies have been performed on surface urban heat islands, only a few have focused on the effect of land cover changes on surface urban heat islands over a long time period. Using six Landsat image scenes of the Metropolitan Development Area of Wuhan, our experiment (1) applied a mapping method for normalized land surface temperatures with three land cover fractions, which were impervious surfaces, non-chlorophyllous vegetation and soil and vegetation fractions, and (2) performed a fitting analysis of fierce change areas in the surface urban heat island intensity based on a time trajectory. Thematic thermal maps were drawn to analyze the distribution of and variations in the surface urban heat island in the study area. A Multiple Endmember Spectral Mixture Analysis was used to extract the land cover fraction information. Then, six ternary triangle contour graphics were drawn based on the land surface temperature and land cover fraction information. A time trajectory was created to summarize the changing characteristics of the surface urban heat island intensity. A fitting analysis was conducted for areas showing fierce changes in the urban heat intensity. Our results revealed that impervious surfaces had the largest impacts on surface urban heat island intensity, followed by the non-chlorophyllous vegetation and soil fraction. Moreover, the results indicated that the vegetation fraction can alleviate the occurrence of surface urban heat islands. These results reveal the impact of the land cover fractions on surface urban heat islands. Urban expansion generates impervious artificial objects that replace pervious natural objects, which causes an increase in land surface temperature and results in a surface urban heat island.

scholarly journals How Do the Multi-Temporal Centroid Trajectories of Urban Heat Island Correspond to Impervious Surface Changes: A Case Study in Wuhan, China

2019 ◽  
Vol 16 (20) ◽  
pp. 3865 ◽  
Author(s):  
Chen Yang ◽  
Qingming Zhan ◽  
Sihang Gao ◽  
Huimin Liu
Keyword(s):  
Urban Heat Island ◽  
Thermal Environment ◽  
Impervious Surface ◽  
Heat Island ◽  
Impervious Surfaces ◽  
Spatiotemporal Variations ◽  
Multi Temporal ◽  
Urban Heat ◽  
Region Scale ◽  
Urban Thermal Environment

Conspicuous expansion and intensification of impervious surfaces accompanied by rapid urbanization are widely recognized to have exerted evident impacts on the urban thermal environment. Investigating the spatially and temporally varying relationships between Land Surface Temperature (LST) and impervious surfaces (IS) at multiple scales is of great significance for steering IS expansion and intensification. This study proposes an analytical framework to investigate the spatiotemporal variations of LST and its responses to IS in Wuhan, China at both city scale and sub-region scale. The summer LST patterns in 2002–2017 are extracted by Multi-Task Gaussian Process (MTGP) model from raw 8-day synthesized MODerate-resolution Imaging Spectroradiometer (MODIS) LST data. At the city scale, the weighted center of LST (LSTWC) and impervious surface fraction (ISFWC), multi-temporal trajectories and coupling indicators are utilized to comprehensively examine the spatial and temporal dynamics of LST and IS within Wuhan. At the sub-region scale, urban heat island ratio index (URI), impervious surfaces contribution index (ISCI) and sprawl rate are introduced for further quantifying the relationships of LST and IS. The results reveal that IS and hot thermal landscapes expanded by 407.43 km2 and 255.82 km2 in Wuhan in 2002–2017 at city scale. The trajectories of LSTWCs and ISFWCs are visually coherent and both heading to southeast direction in general. At the sub-region scale, the specific cardinal directions with the highest ISCI variations are examined to be the exact directions of ISFWC trajectories in 2002–2017. The results reveal that the spatiotemporal variations of LST and IS are highly correlated at both city and sub-region scales within Wuhan, thus testifying the significance of steering IS expansion and renewal for controlling urban thermal environment deterioration.

Study on Urban Thermal Environment based on Diurnal Temperature Range

2020 ◽  
Author(s):  
Zheng Guo ◽  
Miaomiao Cheng
Keyword(s):  
Surface Temperature ◽  
Air Temperature ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Thermal Environment ◽  
Surface Air Temperature ◽  
Heat Island ◽  
Near Surface ◽  
Diurnal Range ◽  
Urban Thermal Environment

&lt;p&gt;Diurnal temperature range (includes land surface temperature diurnal range and near surface air temperature diurnal range) is an important meteorological parameter, which is a very important factor in the field of the urban thermal environmental. Nowadays, the research of urban thermal environment mainly focused on surface heat island and canopy heat island.&lt;/p&gt;&lt;p&gt;Based on analysis of the current status of city thermal environment. Firstly, a method was proposed to obtain near surface air temperature diurnal range in this study, difference of land surface temperature between day and night were introduced into the improved temperature vegetation index feature space based on remote sensing data. Secondly, compared with the district administrative division, we analyzed the spatial and temporal distribution characteristics of the diurnal range of land surface temperature and near surface air temperature.&lt;/p&gt;&lt;p&gt;The conclusions of this study are as follows:&lt;/p&gt;&lt;p&gt;1 During 2003-2012s, the land surface temperature and near surface air temperature diurnal range of Beijing were fluctuating upward. The rising trend of the near surface air temperature diurnal range was more significant than land surface temperature diurnal range. In addition, the rise and decline of land surface temperature and near surface air temperature diurnal range in different districts were different. In the six city districts, the land surface temperature and near surface air temperature diurnal range in the six areas of the city were mainly downward. The decline trend of near surface air temperature diurnal range was more significant than land surface temperature diurnal range.&lt;/p&gt;&lt;p&gt;2 During 2003-2012s, the land surface temperature and near surface air temperature diurnal range of Beijing with similar characteristics in spatial distribution, with higher distribution land surface temperature and near surface air temperature diurnal range in urban area and with lower distribution of land surface temperature and near surface air temperature diurnal range in the Northwest Mountainous area and the area of Miyun reservoir.&lt;/p&gt;

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