CHARACTERISTICS OF TEMPORAL AND SPATIAL VARIATION OF NDVI IN BEIJING AND THE RELATIONSHIP WITH URBAN HEAT ISLAND EFFECT

Vegetation is an important part of ecosystems, and the use of vegetation coverage as an indicator to study the spatio-temporal dynamics of regional vegetation is necessary for ecosystem health evaluation. The urban heat island effect can change the structure and functions of urban ecosystems, and affect the climate, hydrology, atmospheric environment, and energy metabolism of cities, as well as the health of residents. Using Beijing as a case study, this research generates vegetation coverage maps using remote sensing imagery from 1998, 2003, 2008, 2013 and 2018. This study indirectly analyzes the urban heat island effect through spatio-temporal changes in vegetation cover. These analyses offer three key findings. First, vegetation coverage in Beijing from 1998 to 2018 experienced an oscillating upward trend, indicating that the urban heat island effect was weakening. Second, the vegetation coverage in Beijing exhibited a concentric structure, which increased from the central area to the surrounding area, indicating that the urban heat island effect gradually weakens from the inside to the outside of the city. Third, from 1998 to 2008, the normalized difference vegetation index (NDVI) of the areas outside the Sixth Ring Road and inside the Third Ring Road was increasing, therefore the urban heat island effect in these areas was weakening. Conversely, NDVI was decreasing between Sixth Ring Road and Third Ring Road; these areas experienced an increase in the urban heat island effect

中国における都市化総合評価及び環境への影響に関する研究

In Chapter one, research background and significance is investigated. In addition, previous studies and current situation in the research fields was reviewed and discussed. In Chapter two, an in-depth review of prior studies associated with the research topic was conducted. The literature review was carried out from three aspects: urbanization and eco-environment evalution and coordination, urban sprawl assessment and urban heat island investigation. In Chapter three, maximum entropy method was applied to help generate the evaluation system of eco-environment level and urbanization level at provincial scale. Comparison analysis and coordinate analysis was carried through to assess the development of urbanization and eco-environment as well as the balance and health degree of the city develops. In Chapter four, DMSP/OLS stable nighttime light dataset was used to measure and assess the urban dynamics from the extraction of built up area. Urban sprawl was evaluated by analyzing the landscape metrics which provided general understanding of the urban sprawl and distribution pattern characteristics could be got from the evaluation. In Chapter five, the investigation of surface urban heat island effects in Beijing city which derive from land surface temperature retrieval from remote sensing data of Landsat TM was carried out. In addition, spatial correlation and relationship between the urbanization level, vegetation coverage and surface urban heat island was carried out in this chapter. In Chapter six, all the works have been summarized and a conclusion of whole thesis is deduced.北九州市立大

Assess the effect of different degrees of urbanization on land surface temperature using remote sensing images

AbstractUrbanization is a human-dominated process and has greatly impacted biodiversity, ecosystem processes, and regional climate. In this study we assess the effect of different degrees of urbanization on land surface temperature using remote sensing images. Landsat TM images were used for land surface temperature retrieval using the algorithm proposed by Artis and Carnahan. ALOS multispectral images were used for landcover classification using classification trees in three study areas, namely Xicheng district(A), Haidian district(B), Shijingshan district(C), of different degrees of urbanization in Beijing. Landcover-specific surface temperatures were estimated through an inversion alorithm. At the different degrees of urbanization, reducing the within-pixel coverage ratio of vegetations will result in an land surface temperature rise. Quantitative assessment of the relationship between different degrees of urbanization and land surface temperature was simulated by an urbanization index which integrates the coverage ratio of built-up landcover type and the cell-average NDVI. Urbanization indices of the Xicheng district, Haidian district, Shijingshan district were calculated to be 0.91, 0.72, and, 0.55 respectively. Such results are consistent with the trend of evaluation using quantitative estimation land surface temperature

The cooling intensity dependent on landscape complexity of green infrastructure in the metropolitan area

The cooling effect of green infrastructure (GI) is becoming a hot topic on mitigating the urban heat island (UHI) effect. Alterations to the green space are a viable solution for reducing land surface temperature (LST), yet few studies provide specific guidance for landscape planning adapted to the different regions. This paper proposed and defined the landscape complexity and the threshold value of cooling effect (TVoE). Results find that: (1) GI provides a better cooling effect in the densely built-up area than the green belt; (2) GI with a simple form, aggregated configuration, and low patch density had a better cooling intensity; (3) In the densely built-up area, TVoE of the forest area is 4.5 ha, while in the green belt, TVoE of the forest and grassland area is 9 ha and 2.25 ha. These conclusions will help the planners to reduce LST effectively, and employ environmentally sustainable planning

Urban Land Use Land Cover Changes and Their Effect on Urban Thermal Pattern: Case Study of Nigeria’s Federal Capital City

Since the official movement of the seat of government from Lagos to Abuja in 1991, the Federal Capital City being the most habitable area in the entire Federal Capital Territory has continued to experience rising urban population growth; this has resulted in a significant modification of its natural landscape. Such modifications often affect the microclimate of cities. This study investigates the effect of changing urban land use/cover on urban thermal pattern through the application of remote sensing, geographic information systems (GIS) and statistical methods. Land use land cover (LULC) and land surface temperature (LST) were extracted from Landsat 4 TM (1987) and Landsat 8 OLI/TIRS (2014). The result of LULC show that while built-up area and wasteland classes increased by 19.93% (from 23.57% in 1987 to 43.50% in 2014) and 15.87% (from 14.88% in 1987 to 30.75% in 2014) respectively, vegetation cover decreased by 35.63% (from 60.63% in 1987 to 25% in 2014). This significant vegetation cover loss to both built-up area and wasteland is an indication of man’s dominance of the landscape of the city.  The study revealed that the lowest values for minimum, maximum and mean temperature occurred in 1987 (17.03, 31.16 and 24.3°C respectively) while the highest values for minimum, maximum and mean temperature occurred in 2014 (25.01, 37.38 and 32.54°C respectively). In 1987, relatively lower LST values (23-26°C) were dominant occupying about 84.38% of the total land area while, in 2014; higher LST values (31-34°C) were dominant occupying approximately 84.14% of the total land area. These results show that a significant portion of the natural landscape elements of the FCC has been removed due to rapid urbanization and this has resulted in the formation of hotspots across the city. The results of this research bring to fore the need for urban planners in the FCC to put in place temperature-mitigation strategies so as to ensure the sustainability of the city. Keywords: LULC; LST; classification; FCC; SUHI

The Impact of Spatial Form of Urban Architecture on the Urban Thermal Environment: A Case Study of the Zhongshan District, Dalian

The correlation of spatial variation in land surface temperature with building height and density in Zhongshan District, Dalian, China, is investigated over the period 2003-2013. We utilize remote sensing data and multisource land-use data, which we evaluate using a combination of a single-window algorithm and correlation analysis. The results show that: 1) during 2003-2013, the number of high surface temperature regions increased by 4339 grid cells (out of a total of 53 601), with most of the high-temperature grid cells distributed along Jiefang Road and Zhongnan Road in the northern part of Zhongshan District. Ninety-eight percent of grid cells had temperature ranges of 293-309 K in July 2003, 296-310 K in August 2003, 295-308 K in July 2008, 296-311 K in August 2008, 305-314 K in July 2013, and 303-318 K in August 2013; 2) during 2003-2008, the number of low-rise buildings increased by 140%, and the number of multistory buildings increased by 100%. During 2008-2013, the number of buildings in all height categories remained relatively unchanged, with the exception of an 11% decrease in the number of low-rise buildings; 3) surface temperature showed weak correlation with building height (0.314, 0.346, and 0.361 in 2003, 2008, and 2013, respectively) but moderate correlation with building density (0.511, 0.533, and 0.563, respectively)

Revealing Kunming’s (China) historical urban planning policies through Local Climate Zones

Over the last decade, Kunming has been subject to a strong urbanisation driven by rapid economic growth and socio-economic, topographical and proximity factors. As this urbanisation is expected to continue in the future, it is important to understand its environmental impacts and the role that spatial planning strategies and urbanisation regulations can play herein. This is addressed by (1) quantifying the cities' expansion and intra-urban restructuring using Local Climate Zones (LCZs) for three periods in time (2005, 2011 and 2017) based on the World Urban Database and Access Portal Tool (WUDAPT) protocol, and (2) cross-referencing observed land-use and land-cover changes with existing planning regulations. The results of the surveys on urban development show that, between 2005 and 2011, the city showed spatial expansion, whereas between 2011 and 2017, densification mainly occurred within the existing urban extent. Between 2005 and 2017, the fraction of open LCZs increased, with the largest increase taking place between 2011 and 2017. The largest decrease was seen for low the plants (LCZ D) and agricultural greenhouse (LCZ H) categories. As the potential of LCZs as, for example, a heat stress assessment tool has been shown elsewhere, understanding the relation between policy strategies and LCZ changes is important to take rational urban planning strategies toward sustainable city development

An Evaluation of Surface Urban Heat Islands in Two Contrasting Cities

This thesis presents a comparative study on surface urban heat islands effects in Baghdad and Perth. The first part evaluates expansion of built-up areas and quantifies its effects on land surface temperature patterns. The second part examines the extent to which the urban thermal environment is influenced by spatial patterns of land use and land cover (LULC) categories. The final part investigates the thermophysical behaviour of various urban LULC categories using albedo and LST parameters

Characteristics of Winter Urban Heat Island in Budapest at Local and Micro Scale

Most of the urban heat island (UHI) researches focused on the phenomenon in summer. They mainly studied the causes, different functional areas, and possible mitigation measures to reduce the high temperature in urban areas. However, UHI also exists in winter, but there are a limited number of studies on winter UHI. The characteristics and causes of UHI in winter have not been received much attention or consideration yet. This study aims to characterize the UHI feature in winter in Budapest, Hungary, based on the analysis of land surface temperature (LST) in relation to the factors of elevation, slope exposure, residential type, and snow coverage. Five different Landsat images in the winter season were applied to detect the surface temperature; besides, pictures of the thermal camera at a micro-scale were also used. Results showed that UHI intensity was not strong in winter; built-up areas were warmer than other urban areas. Topography was one of the significant factors affecting the surface temperature in winter. The surface temperature of the hills (300 m asl) was lower than that of the lowlands (below 120 m asl). The south-facing slopes and south oriented buildings were warmer than north-facing slopes and buildings oriented to the north. Areas with snow coverage had a lower temperature than no snow coverage areas. These findings could give general guidance for further UHI research, urban planning as well as landscape design