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Mapping global impervious surface area and green space within urban environments

Science China Earth Sciences 2019年第10期62卷 1591-1606页

作者： Wenhui KUANG key laboratory of land Surface Pattern and simulation Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences

The mapping of impervious surface area(ISA) and urban green space(UGS) is essential for improving the urban environmental quality toward ecological, livable, and sustainable goals. Currently, accurate ISA and UGS products are lacking in urban areas at the global scale. This study established regression models that estimated the fraction of ISA/UGS in global 30 cities for validation using MODIS NDVI and DMSP/OLS nighttime light imageries. A global dataset of ISA and UGS fraction with a spatial resolution of 250 m×250 m was developed using the regression model, with a mean relative error of 0.19 for its ISA. The results showed the global urban area of 76.29×10~4 km^2, which was primarily distributed in central Europe, eastern Asia,and central and eastern North America. The urban land area in North America, Europe, and Asia was 66.3×10~4 km^2, accounting for 86.91% of the world’s urban area;the urban land area of the top 50 countries accounted for 59.32% of the total urban land area in the world. The global ISA of 45.26×10~4 km^2 was mainly distributed in central and southern North America, eastern Asia, and Europe, as well as coastal regions around the world. The proportion of ISA situated in built-up areas on the continental scale followed the order of Africa(>70%)>South America>Oceania>Asia(>60%)>North America>Europe(>50%), and these areas were mostly in southeastern North America, southwestern Europe, and eastern and western Asia. North America, Europe, and Asia accounted for 89.44% of the world’s total UGS. The cities of developed countries in Europe and North America exposed a dramatic mosaic of ISA and UGS composites in urban construction. Therefore, the proportion of UGS is relatively high in those cities. However, in developing and underdeveloped countries, the proportion of UGS in built-up areas is relatively low, and urban environments need to be improved for livability.

关键词： Impervious surface area Green space Habitat environment Remote sensing classification Global scale

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Analyzing Asymmetric City Connectivity by Toponym on Social Media in China

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Chinese Geographical Science 2021年第1期31卷 14-26页

作者： YE Xinyue GONG Junfang LI Shengwen Department of landscape Architecture and urban Planning Texas A&M University College StationTX 77843 USA School of Geography and Information Engineering China University of GeosciencesWuhan 430074China key laboratory of urban land resources monitoring and simulation Ministry of Natural ResourcesShenzhen 518034China

The connectedness between cities has become one of the most widely discussed topics in urban and regional research in the mobile and big data era. One problem identified is the asymmetric city connectivity, partially due to data availability. We present a data-driven approach based on location and toponym(place name) extracted from social media data, to assess the asymmetric connectivity between cities. The assumption is that a higher frequency of occurrences of the name of city i in posts located in city j would imply that the city i is more influential than other cities upon city j. In addition, we’ve developed a group of measurements such as the relatedness index, impact index, link strength index, dependence index, and structure similar index to characterize such interactions. This framework of connectivity measurements can also be used to support smart planning taking into account the evolving interplay among cities. The space-time structure of urban systems in China is examined as the case study.

关键词： asymmetric city connectivity social media urban system China

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A Grad-CAM and capsule network hybrid method for remote sensing image scene classification

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Frontiers of Earth Science 2024年第3期18卷 538-553页

作者： Zhan HE Chunju ZHANG Shu WANG Jianwei HUANG Xiaoyun ZHENG Weijie JIANG Jiachen BO Yucheng YANG Shenzhen Data Management Center of Planning and Natural resources Key Laboratory of Urban Land Resources Monitoring and Simulation(Ministry of Natural Resources)Shenzhen 518000China key laboratory of Jianghuai Arable land resources Protection and Eco-restoration(Ministry of Natural resources) Hefei 230088China State key laboratory of resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China School of Civil Engineering Hefei University of TechnologyHefei 230009China

Remote sensing image scene classification and remote sensing technology applications are hot research *** CNN-based models have reached high average accuracy,some classes are still misclassified,such as“freeway,”“spare residential,”and“commercial_area.”These classes contain typical decisive features,spatial-relation features,and mixed decisive and spatial-relation features,which limit high-quality image scene *** address this issue,this paper proposes a Grad-CAM and capsule network hybrid method for image scene *** Grad-CAM and capsule network structures have the potential to recognize decisive features and spatial-relation features,*** using a pre-trained model,hybrid structure,and structure adjustment,the proposed model can recognize both decisive and spatial-relation features.A group of experiments is designed on three popular data sets with increasing classification *** the most advanced experiment,92.67%average accuracy is ***,83%,75%,and 86%accuracies are obtained in the classes of“church,”“palace,”and“commercial_area,”*** research demonstrates that the hybrid structure can effectively improve performance by considering both decisive and spatial-relation ***,Grad-CAM-CapsNet is a promising and powerful structure for image scene classification.

关键词： image scene classification CNN Grad-CAM CapsNet DenseNet

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Volunteered remote sensing data generation with air passengers as sensors

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International Journal of Digital Earth 2021年第2期14卷 158-180页

作者： Chisheng Wang Yongquan Wang Leyang Wang Zhongwen Hu Shaobiao Zhang Shuanglong Wang Wenqun Xiu Hongxing Cui Dan Wang Qingquan Li key laboratory for Geo-Environmental monitoring of Great Bay Area Ministry of Land and ResourcesShenzhen UniversityShenzhenPeople’s Republic of China key laboratory of urban land resources monitoring and simulation Ministry of Land and ResourcesShenzhenPeople’s Republic of China Faculty of Geomatics East China University of TechnologyNanchangPeople’s Republic of China Shenzhen urban Public Safety and Technology Institute ShenzhenPeople’s Republic of China Shenzhen Integrated Geotechnical Investigation&Surveying Co.Ltd ShenzhenPeople’s Republic of China

Remote sensing satellites are playing very important roles in diverse earth observation ***,long revisit period,high cost and dense cloud cover have been the main limitations of satellite remote sensing for a long *** paper introduces the novel volunteered passenger aircraft remote sensing(VPARS)concept,which can partly overcome these *** obtaining aerial imaging data from passengers using a portable smartphone on a passenger aircraft,it has various advantages including low cost,high revisit,dense coverage,and partial anti-cloud,which can well complement conventional remote sensing *** paper examines the concept of VPARS and give general data processing framework of *** cases were given to validate this processing *** preliminary applications on land cover classification and economic activity monitoring validate the applicability of the VPARS ***,we examine the issues about data maintenance,potential applications,limitations and *** conclude the VPARS can benefit both scientific and industrial communities who rely on remote sensing data.

关键词： Volunteered geographic information remote sensing handheld cameras passenger aircraft

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Lagrangian eddies in the Northwestern Pacifi c Ocean

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Journal of Oceanology and Limnology 2022年第1期40卷 66-77页

作者： Qiu HE Fenglin TIAN Xiaokun YANG Ge CHEN Department of Marine Technology College of Information Science and EngineeringOcean University of ChinaQingdao 266100China laboratory for Regional Oceanography and Numerical Modeling Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China key laboratory of urban land resources monitoring and simulation Ministry of Natural ResourcesShenzhen 518034China

The Lagrangian eddies in the western Pacifi c Ocean are identifi ed and analysed based on Maps of Sea Level Anomaly(MSLA)data from 1998 to *** calculating the Lagrangian eddy advected by the AVISO velocity fi eld,we analyzed the variations in Lagrangian eddies and the average transport eff ects on diff erent time *** introducing the Niño coeffi cient,the lag response of the Lagrangian eddy to El Niño is *** data are helpful to further explore the role of mesoscale eddies in ocean energy *** normalized chlorophyll data,we observed chlorophyll aggregation and hole eff ects caused by Lagrangian *** fi ndings demonstrate the important role of Lagrangian eddies in material *** transportation volume of the Lagrangian eddy is calculated quantitatively,and several major transport routes have been identifi ed,which helps us to more accurately and objectively estimate the transport capacity of Lagrangian eddies in the western Pacifi c Ocean.

关键词： Lagrangian coherent structure(LCS) mesoscale eddy distribution character material transport

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Seasonal Variation in Air Temperature and Relative Humidity on Building Areas and in Green Spaces in Beijing, China

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Chinese Geographical Science 2020年第1期30卷 75-88页

作者： KUANG Wenhui key laboratory of land Surface Pattern and simulation Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences

The cooling and humidifying effects of urban parks are an essential component of city ecosystems in terms of regulating microclimates or mitigating urban heat islands(UHIs).Air temperature and relative humidity are two main factors of thermal environmental comfort and have a critical impact on the urban environmental quality of human *** measured the 2-m height air temperature and relative humidity at the Beijing Olympic Park and a nearby building roof for more than 1 year to elucidate seasonal variations in air temperature and relative humidity,as well as to investigate the outdoor thermal *** results showed that the lawn of the park could,on average,reduce the air temperature by(0.80±0.19)℃,and increase the relative humidity by(5.24±2.91)% relative to the values measured at the building roof during *** the nighttime,the lawn of the park reduced the air temperature by(2.64±0.64)℃ and increased the relative humidity by(10.77±5.20)%.The park was cooler and more humid than surrounding building area,especially in night period(more pronounced cooling with 1.84℃).Additionally,the lawn of the park could improve outdoor thermal comfort through its cooling and humidifying *** level of thermal comfort in the park was higher than that around the building roof for a total of 11 days annually in which it was above one or more thermal comfort levels(average reduced human comfort index of 0.92)except during the winter.

关键词： air temperature relative humidity outdoor thermal comfort urban park planning

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Modern pollen assemblages of the surface lake sediments from the steppe and desert zones of the Tibetan Plateau

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Science China Earth Sciences 2021年第3期64卷 425-439页

作者： Feng QIN key laboratory of land Surface Pattern and simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing100101China

Modern pollen analysis is the basis for revealing the palaeovegetation and palaeoclimate changes from fossil pollen *** studies pertaining to the modern pollen assemblages on the Tibetan Plateau have been conducted,but little attention has been paid to pollen assemblages of surface lake *** this study,modern pollen assemblages of surface lake sediments from 34 lakes in the steppe and desert zones of the Tibetan Plateau are investigated and results indicate that the two vegetation zones are dominated by non-arboreal pollen taxa and show distinctive *** pollen assemblages from the desert zone contain substantially high relative abundance of Chenopodiaceae while those from the steppe zone are dominated by *** ratios show great potential in terms of separating different vegetation zones and to indicate climate changes on the Tibetan *** Artemisia/Chenopodiaceae ratio and arboreal/non-arboreal pollen ratio could be used as proxies for winter ***/Cyperaceae ratio and the sum of relative abundance of xerophilous elements increase with enhanced warming and *** considering the vegetation coverage around the lakes,hierarchical cluster analysis suggests that the studied sites can be divided into four clusters:meadow,steppe,desert-steppe,and *** pollen-based vegetation classification models are established using a random forest *** random forest model can effectively separate the modern pollen assemblages of the steppe zone from those of the desert zone on the Tibetan *** model for distinguishing the four vegetation clusters shows a weaker but still valid classifying *** is expected that the random forest model can provide a powerful tool to reconstruct the palaeovegetation succession on the Tibetan Plateau when more pollen data from surface lake sediments are included.

关键词： Modern pollen assemblage Tibetan Plateau Surface lake sediment Pollen-climate relationship Pollen-based vegetation classification model

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Solar forcing of desert vegetation and drought frequency during the last 2700 years in the interior Qaidam Basin, northeastern Tibetan Plateau

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Science China Earth Sciences 2020年第4期63卷 561-574页

作者： Quan LI key laboratory of land Surface Pattern and simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China

Knowledge of long-term change in vegetation and climate in semi-arid/arid regions is essential for the study of current climate and development of mitigation strategies against severe drought. Here, a fossil pollen record of annually-varved core from Sugan Lake in interior Qaidam Basin was quantitatively analyzed to reconstruct changes in vegetation, floristic diversity and drought frequency. Results of biomization suggested that regional vegetation was desert vegetation with three short-term occupations of temperate steppe/xerophytic shrub during the last 2700 years. Floristic diversity generally increased/decreased with the expansion/degradation of desert vegetation. Moisture fluctuations showed three distinct stages(extremely dry between 742 BC and ~AD500, relatively wet with an increasing trend between ~AD500 and 1200 and relatively wet with frequent fluctuations after AD1200), interrupted by 14 drought events. Spectral analysis and continuous wavelet transform of moisture variation revealed 200-and 120-year cycles. According to cross-wavelet transform analysis, major drought frequency of ~200-year was explicitly correlated to solar activity. It's suggested that the centennial-scale drought frequency was mainly driven by solar activity, through modulation of large-scale atmospheric circulation. Furthermore, the effect of surface temperature–evaporation and uplifting/subsiding air flow should be notable. The climatic drought in interior Qaidam Basin could be intensified under the continuous global warming.

关键词： Pollen Vegetation change Drought frequency Qaidam Basin Northeastern Tibetan Plateau

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Chemical fertilizer rate, use efficiency and reduction of cereal crops in China, 1998–2018

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Journal of Geographical Sciences 2022年第1期32卷 65-78页

作者： XIN Liangjie key laboratory of land Surface Pattern and simulation Institute of Geographic Sciences and Natural Resources ResearchCASBeijing 100101China

This paper studied the fertilizer rate(FR), fertilizer use efficiency(FUE) and fertilizer overuse rate(FOR) of rice, corn and wheat in China from 1998 to 2018 and briefly analysed the reasons why farmers were willing to apply more fertilizers.(1) The FR of grain in China reached 373.7 kg/ha in 2018, an increase of 26.8% compared to that in 1998. In 2018, the FR for corn was the highest, at 411.2 kg/ha, compared to the values of 338.3 kg/ha for rice and 371.7 kg/ha for wheat.(2) In recent years, the FUE of grain in China has obviously improved, with values of 32.9% in 1998, 36.7% in 2008, and 39.3% in 2018. In 2018, the FUE for rice was the highest(41.2%), followed by that for corn(39.9%), and the FUE for wheat was the lowest(36.0%).(3) By 2018, fertilizer was overused in all zones of rice, corn and wheat. In 2018, the average FOR for wheat reached 69.0%, which was 35.9% higher than that for corn and 42.8% higher than that for rice.(4) The lower price of chemical fertilizers was the main reason leading to overapplication.(5) Establishing market mechanisms and adjusting regional planting structures can be effective in reducing the application of chemical fertilizers.

关键词： fertilizer rate(FR) fertilizer use efficiency(FUE) fertilizer overuse rate(FOR) China 1998–2018 three main grain crops

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Water and salt movement in different soil textures under various negative irrigating pressures

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Journal of Integrative Agriculture 2016年第8期15卷 1874-1882页

作者： WANG Jia-jia HUANG Yuan-fang LONG Huai-yu Department of Soil and Water Sciences College of Resources and Environmental Sciences China Agricultural University/Key Laboratory of Arable Land Conservation (North China) Minstry of Agriculture/Key Laboratory of Agricultural Land Quality Monitoring Ministry of Land and Resources Institute of Agricultural resources and Regional Planning Chinese Academy of Agricultural Sciences

supported by the National High-Tech R＆D Program of China （2013AA102901）

关键词： negative pressure irrigation volumetric water content soil salt content soil texture

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