Urban areas and its evolution are important anthropogenic indicators and human ecological footprints, and play decisive roles in environmental change analysis, global geo-conditional monitoring, and sustainable develo...Urban areas and its evolution are important anthropogenic indicators and human ecological footprints, and play decisive roles in environmental change analysis, global geo-conditional monitoring, and sustainable development. China has the highest rate of urban expansion and has emerged as an urban expansion hotspot worldwide. In this paper, the progress of studies on Chinese urban expansion based on remote sensing technology are summarized and analyzed from the aspects of urban area definition, remotely sensed imagery applied in urban expansion, monitoring methods of urban expansion, and urban expansion applications. Existing issues and future directions of Chinese urban expansion are discussed and proposed. Results indicate that: 1) The fusion of multi-source remotely sensed imagery is imperative to meet the needs of urban expansion with various monitoring terms and frequencies on different scales and dimensions. 2) To guarantee the classification accuracy and efficiency and describe urban expansion and its influences on local land use simultaneously, the combination of visual interpretation and automatic classification is the tendency of future monitoring methods of urban areas. 3) Urban expansion data have become the prerequisite for recognizing the urban development process, excavating its driving forces, simulating and predicting the future development directions, and also is conducive to revealing and explaining urban ecological and environmental issues. 4) In the past decades, Chinese scholars have promoted the application of remote sensing technology in the urban expansion field, with data construction, methods and models developing from the quotation stage to improvement and innovation stage; however, an independent and consistent urban expansion data on the national scale with long-term and high-frequency(such as annual monitoring) monitoring is still lacking.展开更多
Urbanization has introduced a series of environmental problems worldwide,and particulate matter(PM)is one of the main threats to human health.Due to the lack of high-resolution,large-scale monitoring data,few studies ...Urbanization has introduced a series of environmental problems worldwide,and particulate matter(PM)is one of the main threats to human health.Due to the lack of high-resolution,large-scale monitoring data,few studies have analyzed the intraurban spatial distribution pattern of PM at a fine scale.In this study,portable air monitors carried by five taxis were used to collect the concentrations of PM1,PM2.5 and PM10 for five months in Shenyang during the heating season.The results showed that high concentrations of PM were distributed in the suburbs,while relatively low concentration areas were found in the central area.Agricultural,industrial and development zones had higher concentration values among the eight observed types.The PM concentration exhibited strong spatial autocorrelation based on Moran’s I index analysis.Meteorological factors were the most important influencing factors of the three pollutants,and their total contribution rate accounted for more than 80%among the 13 factors according to boosted regression trees analysis.The taxi monitoring method we proposed was a more efficient and feasible method for monitoring urban air pollution and could obtain higher spatial-temporal resolution data at a lower cost to elucidate the region’s dynamic air pollution distribution patterns.展开更多
基金Under the auspices of National Major Science and Technology Program for Water Pollution Contro and Treatment(No.2017ZX07101001)International Partnership Program of Chinese Academy of Sciences(No.131C11KYSB20160061)
文摘Urban areas and its evolution are important anthropogenic indicators and human ecological footprints, and play decisive roles in environmental change analysis, global geo-conditional monitoring, and sustainable development. China has the highest rate of urban expansion and has emerged as an urban expansion hotspot worldwide. In this paper, the progress of studies on Chinese urban expansion based on remote sensing technology are summarized and analyzed from the aspects of urban area definition, remotely sensed imagery applied in urban expansion, monitoring methods of urban expansion, and urban expansion applications. Existing issues and future directions of Chinese urban expansion are discussed and proposed. Results indicate that: 1) The fusion of multi-source remotely sensed imagery is imperative to meet the needs of urban expansion with various monitoring terms and frequencies on different scales and dimensions. 2) To guarantee the classification accuracy and efficiency and describe urban expansion and its influences on local land use simultaneously, the combination of visual interpretation and automatic classification is the tendency of future monitoring methods of urban areas. 3) Urban expansion data have become the prerequisite for recognizing the urban development process, excavating its driving forces, simulating and predicting the future development directions, and also is conducive to revealing and explaining urban ecological and environmental issues. 4) In the past decades, Chinese scholars have promoted the application of remote sensing technology in the urban expansion field, with data construction, methods and models developing from the quotation stage to improvement and innovation stage; however, an independent and consistent urban expansion data on the national scale with long-term and high-frequency(such as annual monitoring) monitoring is still lacking.
基金Funding for this project was provided by the National Natural Science Foundation of China(Nos.41730647 and 32071580)。
文摘Urbanization has introduced a series of environmental problems worldwide,and particulate matter(PM)is one of the main threats to human health.Due to the lack of high-resolution,large-scale monitoring data,few studies have analyzed the intraurban spatial distribution pattern of PM at a fine scale.In this study,portable air monitors carried by five taxis were used to collect the concentrations of PM1,PM2.5 and PM10 for five months in Shenyang during the heating season.The results showed that high concentrations of PM were distributed in the suburbs,while relatively low concentration areas were found in the central area.Agricultural,industrial and development zones had higher concentration values among the eight observed types.The PM concentration exhibited strong spatial autocorrelation based on Moran’s I index analysis.Meteorological factors were the most important influencing factors of the three pollutants,and their total contribution rate accounted for more than 80%among the 13 factors according to boosted regression trees analysis.The taxi monitoring method we proposed was a more efficient and feasible method for monitoring urban air pollution and could obtain higher spatial-temporal resolution data at a lower cost to elucidate the region’s dynamic air pollution distribution patterns.
