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Environmental Monitoring in Northern Aksu, China Based on Remote Sensing Ecological Index Model 被引量:1
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作者 Yun Zhang Liangjun Zhao +1 位作者 Kai Niu Asiya Manlike 《Open Journal of Applied Sciences》 2022年第5期757-768,共12页
In order to understand the development status of ecological environment quality in the Aksu region of China, to effectively adjust the ecological environment quality, so as to promote the sustainable development of it... In order to understand the development status of ecological environment quality in the Aksu region of China, to effectively adjust the ecological environment quality, so as to promote the sustainable development of its social economy and ecological environment protection. This paper selects the Landsat series remote sensing images of the northern Aksu region in 2013, 2016, and 2019, and uses the tools such as ENVI5.3 and ArcGIS 10.8.1 to process the image data accordingly. The principal component analysis method is used to calculate the Remote Sensing Ecological Index (RSEI) of the northern Aksu region. The data show that: 1) The ecological environment quality index in the northern Aksu region in 2013, 2016, and 2019 was 0.706087, 0.25243 and 0.362991 respectively;2) The areas where the ecological environment quality declined significantly in the northern Aksu region were the human settlements and the Gobi, fan-shaped land and other special terrain areas;3) The humidity index and the heat index are the two factors that have the greatest impact on the ecological environment quality in the northern Aksu area. The data as a whole show that the ecological environment in the northern part of the Aksu region has deteriorated seriously, and the severely deteriorated area is close to the human living area. 展开更多
关键词 Aksu china Ecological Environment Quality Principal Component Analysis Remote Sensing Ecological index
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Spatial-temporal changes and driving factors of eco-environmental quality in the Three-North region of China 被引量:10
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作者 LONG Yi JIANG Fugen +2 位作者 DENG Muli WANG Tianhong SUN Hua 《Journal of Arid Land》 SCIE CSCD 2023年第3期231-252,共22页
Eco-environmental quality is a measure of the suitability of the ecological environment for human survival and socioeconomic development.Understanding the spatial-temporal distribution and variation trend of eco-envir... Eco-environmental quality is a measure of the suitability of the ecological environment for human survival and socioeconomic development.Understanding the spatial-temporal distribution and variation trend of eco-environmental quality is essential for environmental protection and ecological balance.The remote sensing ecological index(RSEI)can quickly and objectively quantify eco-environmental quality and has been extensively utilized in regional ecological environment assessment.In this paper,Moderate Resolution Imaging Spectroradiometer(MODIS)images during the growing period(July-September)from 2000 to 2020 were obtained from the Google Earth Engine(GEE)platform to calculate the RSEI in the three northern regions of China(the Three-North region).The Theil-Sen median trend method combined with the Mann-Kendall test was used to analyze the spatial-temporal variation trend of eco-environmental quality,and the Hurst exponent and the Theil-Sen median trend were superimposed to predict the future evolution trend of eco-environmental quality.In addition,ten variables from two categories of natural and anthropogenic factors were analyzed to determine the drivers of the spatial differentiation of eco-environmental quality by the geographical detector.The results showed that from 2000 to 2020,the RSEI in the Three-North region exhibited obvious regional characteristics:the RSEI values in Northwest China were generally between 0.2 and 0.4;the RSEI values in North China gradually increased from north to south,ranging from 0.2 to 0.8;and the RSEI values in Northeast China were mostly above 0.6.The average RSEI value in the Three-North region increased at an average growth rate of 0.0016/a,showing the spatial distribution characteristics of overall improvement and local degradation in eco-environmental quality,of which the areas with improved,basically stable and degraded eco-environmental quality accounted for 65.39%,26.82%and 7.79%of the total study area,respectively.The Hurst exponent of the RSEI ranged from 0.20 to 0.76 and the future trend of eco-environmental quality was generally consistent with the trend over the past 21 years.However,the areas exhibiting an improvement trend in eco-environmental quality mainly had weak persistence,and there was a possibility of degradation in eco-environmental quality without strengthening ecological protection.Average relative humidity,accumulated precipitation and land use type were the dominant factors driving the spatial distribution of eco-environmental quality in the Three-North region,and two-factor interaction also had a greater influence on eco-environmental quality than single factors.The explanatory power of meteorological factors on the spatial distribution of eco-environmental quality was stronger than that of topographic factors.The effect of anthropogenic factors(such as population density and land use type)on eco-environmental quality gradually increased over time.This study can serve as a reference to protect the ecological environment in arid and semi-arid regions. 展开更多
关键词 eco-environmental quality remote sensing ecological index Google Earth Engine Hurst exponent geographical detector Three-North region of china
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Evaluation of Forest Damaged Area and Severity Caused by Ice-snow Frozen Disasters over Southern China with Remote Sensing 被引量:2
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作者 WANG Xuecheng YANG Fei +2 位作者 GAO Xing WANG Wei ZHA Xinjie 《Chinese Geographical Science》 SCIE CSCD 2019年第3期405-416,共12页
The accurate assessment of forest damage is important basis for the forest post-disaster recovery process and ecosystem management. This study evaluates the spatial distribution of damaged forest and its damaged sever... The accurate assessment of forest damage is important basis for the forest post-disaster recovery process and ecosystem management. This study evaluates the spatial distribution of damaged forest and its damaged severity caused by ice-snow disaster that occurred in southern China during January 10 to February 2 in 2008. The moderate-resolution imaging spectroradiometer(MODIS)13 Q1 products are used, which include two vegetation indices data of NDVI(Normalized Difference Vegetation Index) and EVI(Enhanced Vegetation Index). Furtherly, after Quality Screening(QS) and Savizky-Golay(S-G) filtering of MODIS 13 Q1 data, four evaluation indices are obtained, which are NDVI with QS(QSNDVI), EVI with QS(QSEVI), NDVI with S-G filtering(SGNDVI) and EVI with S-G filtering(SGEVI). The study provides a new way of firstly determining the threshold for each image pixel for damaged forest evaluation, by computing the pre-disaster reference value and change threshold with vegetation index from remote sensing data. Results show obvious improvement with the new way for forest damage evaluation, evaluation result of forest damage is much close to the field survey data with standard error of only 0.95 and 1/3 less than the result that evaluated from other threshold method. Comparatively, the QSNDVI shows better performance than other three indices on evaluating forest damages. The evaluated result with QSNDVI shows that the severe, moderate, mild damaged rates of Southern China forests are 47.33%, 34.15%, 18.52%, respectively. By analyzing the influence of topographic and meteorological factors on forest-vegetation damage, we found that the precipitation on freezing days has greater impact on forest-vegetation damage, which is regarded as the most important factor. This study could be a scientific and reliable reference for evaluating the forest damages from ice-snow frozen disasters. 展开更多
关键词 ice-snow DISASTER vegetation index forest remote sensing SOUtheRN china
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Study of Sand Dunes and Their Effect on Desertification of Cultivated Lands in Shaanxi Province, China Using Remote Sensing Techniques 被引量:1
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作者 Mushtak Talib Jabbar Hu Guangdao Chen Jianguo Faculty of Earth Resources, China University of Geosciences, Wuhan 430074 《Journal of China University of Geosciences》 SCIE CSCD 2002年第3期234-239,共6页
About half of the arid and semi-arid lands in the world are deserts thatcomprise various types of aeolian sand dunes deposits. In Shaanxi Province, aeolian sand dunes coverconsiderable areas of the Yulin desert and no... About half of the arid and semi-arid lands in the world are deserts thatcomprise various types of aeolian sand dunes deposits. In Shaanxi Province, aeolian sand dunes coverconsiderable areas of the Yulin desert and northern Jinbian. Sand dunes are moving in the main winddirection and converting some agricultural area to wasteland. Remote sensing of sand dunes helps inthe understanding of aeolian process and desertification. Remote sensing data combined with fieldstudies are valuable in studying sand dunes, regional aeolian depositional history. In particular,active and inactive sand dunes of the north Shaanxi Province were studied using remote sensing andgeographic information system. In this study, we describe the Landsat thematic mapper (TM) images,covering north Shaanxi Province, which were used to study the distribution, shape, size, trends,density and movement of sand dunes and their effect on desertification of cultivated lands.Estimation was made depending on soil erodibility factor (Ⅰ) and local climatic factor (C) duringthe period (June to September). The result indicates that soil erosion caused sand drift of 8.957 5,7. 03 ton for Yulin and Jinbian, respectively. The mean sand dunes movement rate were 4.37, 3.11 m,whereas, monthly sand dune advance rate were 1. 092 5, 0. 777 5m, for the two locations,respectively. The study reveals that cultivated lands extended obliquely to the direction of sanddune movement are extremely affected, while other segments that extend parallel to the direction ofthe movement are not affected. Accordingly the north Shaanxi Province was divided into areas ofdifferent classes of potential risk. Moreover, blown sands and sand movement from neighboringhighlands also affect the area of western desert. 展开更多
关键词 sand dunes DESERTIFICATION remote sensing crust index china
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Spatio-temporal Evolution of Urban Expansion Based on a Novel Adjusted Index and GEE: A Case Study of Central Plains Urban Agglomeration, China
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作者 SU Yanlin LU Chunyan +3 位作者 SU Yue WANG Zili HUANG Yufei YANG Nuocheng 《Chinese Geographical Science》 SCIE CSCD 2023年第4期736-750,共15页
It is crucial to investigate the urban agglomerations spatio-temporal evolution patterns and driving factors for analyzing the urban spatial structure-functional division and promoting the coordinated development of u... It is crucial to investigate the urban agglomerations spatio-temporal evolution patterns and driving factors for analyzing the urban spatial structure-functional division and promoting the coordinated development of urban agglomerations.In this study,a novel vegetation-building-nighttime light-adjusted index(VBNAI)was established for rapid and effective mapping of urban construction land(UCL)in Central Plains Urban Agglomeration(CPUA),China during 2000–2020 based on Google Earth Engine(GEE)platform.Compared with traditional indices,VBNAI can significantly decrease the blooming effect,Normalized Difference Vegetation Index(NDVI)saturation,and soil background of nighttime light data.In addition,the urban expansion indices and standard deviation ellipse model were synthetically adopted to analyze the spatio-temporal evolution pattern of urban expansion.The gravity model and the geographically weighted regression model were employed to determine the spatial interaction forces and drivers of urban expansion,respectively.The results showed that the VBNAI index has obvious advantages in efficiency and accuracy to extract UCL with the overall accuracy of more than 91%.The UCL of CPUA had increased by 4489.84 km2 during 2000–2020 with the gravity center moving towards southeast continuously.From 2000 to 2010,the urban expansion was in a‘center-hinterland’pattern which had benefit from the favorable effect of the traffic shaft belt.During 2010–2020,the urban network structure had basically established.Urban expansion had been influenced by a variety of socio-economic and demographic factors,and the impact degree varied from region to region.This study could provide scientific references for facilitating the intensive utilization of urban resources and optimizing the spatial development pattern of urban agglomeration. 展开更多
关键词 urban expansion urban construction land(UCL)mapping vegetation-building-nighttime light-adjusted index(VBNAI) multi-source remote sensing Google Earth Engine(GEE) Central Plains Urban Agglomeration(CPUA) china
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Distribution of lipids in modern soils from various regions with continuous climate (moisture-heat) change in China and their climate significance 被引量:12
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作者 WANG YongLi FANG XiaoMin +3 位作者 BAI Yan XI XiaoXia ZHANG XiZheng WANG YouXiao 《Science China Earth Sciences》 SCIE EI CAS 2007年第4期600-612,共13页
Total 26 modern soil samples were collected from various regions under different climate conditions from tropical to arid temperate in China and systematically analyzed for their organic matters by GC/MS in order to e... Total 26 modern soil samples were collected from various regions under different climate conditions from tropical to arid temperate in China and systematically analyzed for their organic matters by GC/MS in order to evaluate climatic impacts on soil organic components. Abundant lipids molecules were recognized, including n-alkanes, n-alkenones, and long-chain branched alkanes. We find the pre- dominance of main peaks of long-chain n-alkanes (nC29, nC31, nC33) and short-chain ones (nC16, nC17, nC18) records information of soil generation in warm-humid and cold-dry regions. The proportion of n-alkanes (nC16+nC17+nC18) to (nC29+nC31+nC33) varies in good agreement with moisture-heat conditions and thus probably can serve as a new index for climate change. The ratios of C21-/nC22+, nC17/nC31 and (nC15+nC17+nC19) / ( nC27+nC29 +nC31) of n-alkanes, indicating respectively input ratios of lower bacterial alga, aquatic organisms, and higher plants and terraneous organisms, co-vary well in different climate regions from forest to grassland and desert, suggesting that they have also reflected the difference of climates between monsoon region and inland one. The C21-/C22+ ratio of n-alkan-2-one records largely the discrepancy of temperature from north to south of China bordered by the Qinling Mountains, but less humidity. The C21-/C22+ ratio of n-alkan-3-ones changes well with climatic factors, such as tem- perature and humidity. The biogenic source of series A-D long-chain branched alkanes may be derived from some kinds of special epiphyte that most likely live in weak oxic-anoxic and moisture-heat envi- ronments, suggesting their distribution record as well some information on climatic change. All these researches demonstrate that the distributions of lipids molecules in modern soils in China record well signals of climates from quite different climatic regions, and can serve as important climatic proxies to reveal climatic change over China. 展开更多
关键词 LIPIDS molecule modern soil CLIMATE (moisture-heat) continuously changing REGIONS CLIMATE index china
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Does palynological diversity reflect floristic diversity?A case study from Northeast China
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作者 Yifan CUI Feng QIN +3 位作者 Yan ZHAO Qiaoyu CUI Rongwei GENG Quan LI 《Science China Earth Sciences》 SCIE EI CAS CSCD 2023年第9期2097-2108,共12页
Fossil pollen data can provide important information of past vegetation diversity,on the basis of established relationship between modern palynological and floristic diversity.However,current studies on modern pollen ... Fossil pollen data can provide important information of past vegetation diversity,on the basis of established relationship between modern palynological and floristic diversity.However,current studies on modern pollen assemblages in China have not examined this relationship yet.Herein,we report a case study from Northeast China,aiming to investigate the representation of modern palynological diversity to regional floristic diversity.A total of 87 sets of modern pollen and vegetation data from various vegetation types were applied to assess modern palynological diversity and floristic diversity in Northeast China,and the relationship between palynological and floristic diversity was studied using spatial pattern comparison and correlation analysis.Moreover,to reduce representation bias related to pollen production and dispersal,we calibrated pollen data using the Regional Estimates of Vegetation Abundance from Large Sites(REVEALS)model with Pollen Productivity Estimates(PPEs)and Fall Speeds of Pollen(FSP).The results show that the spatial variations of palynological and floristic richness among vegetation types are similar,and have a good positive correlation(r=0.41,p<0.01).However,palynological evenness presents a different spatial pattern from floristic evenness,with a weaker positive correlation(r=0.21,p>0.05).The calibration on pollen data using REVEALS model minimized the differences in spatial patterns between palynological and floristic diversity,and improved the correlations between them(richness,r=0.50,p<0.01;evenness,r=0.33,p<0.01).Our study indicates that palynological richness in Northeast China could reflect regional floristic richness in general,and the calibration with REVEALS model is recommended for reconstructing past floristic diversity from pollen data. 展开更多
关键词 Northeast china modern palynological diversity Floristic diversity Richness and evenness Community dissimilarity index REVEALS model
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中国乡村教育指数的构建与测算 被引量:1
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作者 张炜 周洪宇 《统计与决策》 CSSCI 北大核心 2024年第1期41-45,共5页
在大数据时代背景下,为推进教育强国建设,面向中国乡村教育的指数研究亟待开展。文章利用乡村教育现代化CQS模型、德尔菲法、层次分析法构建并测算了2016年和2021年的中国乡村教育指数,结果显示:与2016年相比,2021年中国乡村教育发展势... 在大数据时代背景下,为推进教育强国建设,面向中国乡村教育的指数研究亟待开展。文章利用乡村教育现代化CQS模型、德尔菲法、层次分析法构建并测算了2016年和2021年的中国乡村教育指数,结果显示:与2016年相比,2021年中国乡村教育发展势头持续向好,中西部地区省份不仅在综合指数的得分上持续提升,而且在师资建设指数、学生支持指数、教育生态指数上与北京的整体差距均有不同程度的缩小。分区域来看,中国乡村教育发展虽不存在“马太效应”,但仍然存在“中部塌陷”现象,其“东南强、西部弱、东北滞、中部塌陷”的旧格局仍未被打破。在加快建设教育强国的重大战略部署下,充分利用好制度、政策、技术等方面的后发优势,因地制宜、持之以恒地改善乡村教育生态,最终实现“破局”,将成为“十四五”时期至2035年国家教育治理推进“义务教育优质均衡发展和城乡一体化”目标的重点和关键。 展开更多
关键词 中国乡村教育指数 中部塌陷 教育强国 乡村教育现代化CQS模型
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Mapping paddy rice with multi-date moderate-resolution imaging spectroradiometer (MODIS) data in China 被引量:13
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作者 Hua-sheng SUN Jing-feng HUANG +2 位作者 Alfredo R. HUETE Dai-liang PENG Feng ZHANG 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2009年第10期1509-1522,共14页
The objective of this study was to obtain spatial distribution maps of paddy rice fields using multi-date moderate-resolution imaging spectroradiometer(MODIS) data in China.Paddy rice fields were extracted by identify... The objective of this study was to obtain spatial distribution maps of paddy rice fields using multi-date moderate-resolution imaging spectroradiometer(MODIS) data in China.Paddy rice fields were extracted by identifying the unique char-acteristic of high soil moisture in the flooding and transplanting period with improved algorithms based on rice growth calendar regionalization.The characteristic could be reflected by the enhanced vegetation index(EVI) and the land surface water index(LSWI) derived from MODIS sensor data.Algorithms for single,early,and late rice identification were obtained from selected typical test sites.The algorithms could not only separate early rice and late rice planted in the same fields,but also reduce the uncertainties.The areal accuracy of the MODIS-derived results was validated by comparison with agricultural statistics,and the spatial matching was examined by ETM+(enhanced thematic mapper plus) images in a test region.Major factors that might cause errors,such as the coarse spatial resolution and noises in the MODIS data,were discussed.Although not suitable for monitoring the inter-annual variations due to some inevitable factors,the MODIS-derived results were useful for obtaining spatial distribution maps of paddy rice on a large scale,and they might provide reference for further studies. 展开更多
关键词 Remote sensing Moderate-resolution imaging spectroradiometer (MODIS) Enhanced vegetation index (EVI) Land surface water index (LSWI) Paddy rice china
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中国式现代化视域下中华民族共同体意识培育铸牢的逻辑理路
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作者 蒋永发 《广西民族研究》 CSSCI 北大核心 2024年第2期51-58,共8页
“中国式现代化”与“铸牢中华民族共同体意识”作为习近平新时代中国特色社会主义思想的重要内容,二者在逻辑上贯通、价值上契合、归旨上一致。中华民族伟大复兴的美好愿景框定了共同奋斗目标,为维护各族人民的根本利益指明了共同价值... “中国式现代化”与“铸牢中华民族共同体意识”作为习近平新时代中国特色社会主义思想的重要内容,二者在逻辑上贯通、价值上契合、归旨上一致。中华民族伟大复兴的美好愿景框定了共同奋斗目标,为维护各族人民的根本利益指明了共同价值关切,为坚持中国共产党的领导提供了共同政治保障。以中国式现代化推进中华民族共同体建设是实现中华民族伟大复兴的根本要求,需推动经济、政治、文化、社会、生态“五个文明”协调一体发展。要在实现高质量发展中打牢各族人民幸福生活的物质基础;在发展全过程人民民主中夯实各族人民团结进步的政治根基;在推进文化自信自强中赓续各族人民共同拥有的文化血脉;在增进民生福祉中巩固各族人民团结和睦的社会基础;在实现人与自然和谐共生中建设各族人民共同生活的绿色家园。 展开更多
关键词 中国式现代化 中华民族共同体意识 中华民族伟大复兴 中国共产党
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我国省级生态文明治理体系与治理能力现代化程度评估方法与实证研究
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作者 贾真 李晓亮 +3 位作者 李婕旦 王青 冀云卿 董战峰 《环境影响评价》 2024年第4期32-38,共7页
生态文明治理体系与治理能力现代化既是推进美丽中国建设的动力工具,也是美丽中国建设达到较高水平的显性标志。本文以生态文明治理体系与治理能力为主题,采用主题框架模型,构建了省级生态文明治理体系与治理能力现代化程度评估指标体系... 生态文明治理体系与治理能力现代化既是推进美丽中国建设的动力工具,也是美丽中国建设达到较高水平的显性标志。本文以生态文明治理体系与治理能力为主题,采用主题框架模型,构建了省级生态文明治理体系与治理能力现代化程度评估指标体系;设计了法治化程度、体制机制健全度、制度完备度、体系有效性、生态环境保护能力、社会与公众参与能力6项二级指标和18项三级指标,并利用隶属函数建立综合指数评价方法,开展了省级层面的指数实证评估;通过分析发现治理体系与治理能力存在区域间、领域间差异与不平衡,并提出了进一步提升生态文明治理体系与治理能力现代化水平的政策建议。 展开更多
关键词 美丽中国 治理体系 治理能力 现代化程度 指数
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党、团、队一体化“育新人”的评价指标体系及应用
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作者 栾淳钰 白洁 《天津大学学报(社会科学版)》 2024年第6期497-504,共8页
入队、入团、入党,是青年追求政治进步的“人生三部曲”。构建党、团、队一体化“育新人”的评价指标体系是青少年奏好“人生三部曲”的衡量依据和重要抓手。从历史、理论、现实三重维度出发,党、团、队一体化“育新人”的评价指标体系... 入队、入团、入党,是青年追求政治进步的“人生三部曲”。构建党、团、队一体化“育新人”的评价指标体系是青少年奏好“人生三部曲”的衡量依据和重要抓手。从历史、理论、现实三重维度出发,党、团、队一体化“育新人”的评价指标体系包括胸怀“两个大局”的总体性评价指标、“德智体美劳”全要素评价的静态性评价指标、“入队、入团、入党”阶梯式评价的动态化评价指标。基于“时代新人铸魂工程”对一体化育人的要求,应从“队伍+合力”“理论+制度”“资源+平台”多元角度,促进评价指标体系落地、落实、落细,发挥党、团、队一体化“育新人”评价指标体系的现实价值,助力培养担当民族复兴重任的时代新人。 展开更多
关键词 党团队 一体化 时代新人 现代化 评价指标
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Ecological Assessment of Oxygen Balance:A Case Study of China’s Natural Oxygen Bars
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作者 Hao GAO Xiuzhen HAN +2 位作者 Xiurong WANG Yu FU Chen MIAO 《Journal of Meteorological Research》 SCIE CSCD 2023年第3期404-416,共13页
Ecological assessment plays a vital role in sustainable development of the environment,and thus exploration of specific and integrated ecological assessment methods has become a critical task.In this study,based on th... Ecological assessment plays a vital role in sustainable development of the environment,and thus exploration of specific and integrated ecological assessment methods has become a critical task.In this study,based on the concept of oxygen balance and by accommodating both natural factors and socioeconomic elements,we establish an oxygen(O_(2))balance index(OBI),i.e.,the ratio of the O_(2)production from the ecosystem to the O_(2)consumption by human behavior,based on the net primary productivity(NPP),fuel consumption,gross domestic production(GDP),population data,and so on.The results show that the spatial distributions of OBI in China are intimately correlated to the regional vegetation and socioeconomic development.The estimated OBI values are then validated by statistical data from 27 counties in China,and it is found that the OBI reflects the ecological environment status well.Moreover,the average OBI values derived from 190 natural oxygen bars in China reveal extreme imbalance between O_(2)production and consumption in highly developed regions,especially in the cities,in contrast to good O_(2)balance in areas with high-quality ecological status and less industrialization.The findings from this study have quantitatively captured the regional ecological quality,providing guidance for sustainable natural and socioeconomic developments in local areas of China. 展开更多
关键词 oxygen balance index(OBI) ecological environment remote sensing china’s natural oxygen bars meteorological satellites
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基于ROTI和AATR的测地型GNSS接收机监测北半球高纬度区域电离层闪烁准确性分析
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作者 赵东升 张雪礼 +5 位作者 崔双雷 王潜心 李冠青 李龙江 李宸栋 张克非 《测绘学报》 EI CSCD 北大核心 2024年第7期1251-1264,共14页
当前,第25个太阳周期已进入强活跃时期,能引发大量电离层不规则体,进而对使得穿行其中的GNSS信号产生电离层闪烁。这已成为影响GNSS全球稳定导航定位服务的重要干扰源。对全球电离层闪烁进行广泛且全面的监测是消除闪烁对GNSS干扰的重... 当前,第25个太阳周期已进入强活跃时期,能引发大量电离层不规则体,进而对使得穿行其中的GNSS信号产生电离层闪烁。这已成为影响GNSS全球稳定导航定位服务的重要干扰源。对全球电离层闪烁进行广泛且全面的监测是消除闪烁对GNSS干扰的重要前提,然而传统电离层闪烁监测接收机(ISMR)分布有限,无法满足闪烁全球监测需求;测地型接收机分布广泛,但从其低采样数据中提取的闪烁因子缺乏新太阳周期长时序监测数据验证,导致其闪烁监测可靠性存疑。为此,本文基于近3 a新太阳周期测地型接收机数据,以ISMR提供的闪烁因子为参考,从代表性空间天气事件闪烁响应、日闪烁发生率、闪烁持续时间概率分布、闪烁日发生规律及其随极昼、极夜、地磁指数的特征变化等方面,对比研究了两种测地型接收机电离层闪烁因子(即电离层总电子含量变化率指数ROTI和沿弧段电子含量变化率指数AATR)监测北极高纬度区域电离层闪烁的准确性,并给出了ROTI和AATR在高纬度区域判断闪烁发生的经验阈值。结果表明,ROTI和AATR均能较为准确探测到地磁扰动、太阳活动等因素驱动的区域电离层闪烁,并能有效表征电离层闪烁统计学上的日变化规律,但两种闪烁因子不能准确区分闪烁和电离层电子密度梯度变化,导致在电子密度梯度变化剧烈期间存在较高虚警。该研究成果可为准确选择区域电离层闪烁监测因子提供指导。 展开更多
关键词 GNSS 电离层闪烁 相位闪烁因子 测地型接收机
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近20年中国耕地复种指数的时空变化 被引量:114
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作者 闫慧敏 刘纪远 曹明奎 《地理学报》 EI CSCD 北大核心 2005年第4期559-566,共8页
多熟种植是中国重要的种植制度,对保障国家食物安全和促进农村经济发展有十分重要的意义。复种指数受自然条件和农村社会状况的影响处于不断变化之中,及时获取其变化信息是国家食物安全评估和农业发展科学决策的基础。近年来对食物安全... 多熟种植是中国重要的种植制度,对保障国家食物安全和促进农村经济发展有十分重要的意义。复种指数受自然条件和农村社会状况的影响处于不断变化之中,及时获取其变化信息是国家食物安全评估和农业发展科学决策的基础。近年来对食物安全的研究集中于耕地面积变化的影响,对复种指数变化及其影响的研究较少。作物种植面积和复种指数变化的估计一直以行政区划为单元的统计数据为基础,但获得这些数据费时费力,时效性和可靠性都比较差,更缺乏准确的空间和时间变化信息。卫星遥感是探测大尺度土地覆被格局实时变化的最有效手段,因此可以作为获取全国和区域尺度作物复种指数变化信息的重要途径。作者应用多时相NOAA/AVHRR遥感观测数据和峰值特征点检测法提取全国尺度的复种指数,并分析其从20世纪80年代初到90年代末的变化。结果表明全国复种指数整体增加,但在珠江三角洲、长江中下游、四川盆地丘陵山地以及山东丘陵等地区有所降低。复种指数下降的耕地占全国总面积15%左右。在四川盆地和黄淮海区,复种指数在平原地区有所增加或保持稳定,下降多发生在丘陵山地,但在长江中下游和华南精耕细作地区出现复种指数降低的趋势。 展开更多
关键词 遥感观测 种植制度 复种指数 时空变化 中国 耕地 20世纪80年代 NOAA/AVHRR 农村经济发展 长江中下游
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基于长时间序列NDVI资料的我国西北干旱区植被覆盖动态监测 被引量:28
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作者 王玮 冯琦胜 +4 位作者 郭铌 沙莎 胡蝶 王丽娟 李耀辉 《草业科学》 CAS CSCD 北大核心 2015年第12期1969-1979,共11页
植被是表征陆地生态系统的重要指标,气候变化对植被具有显著影响。虽然MODIS NDVI具有较高的精度,但时间序列长度有限,在年代际尺度的变化趋势研究中,仍然需要对AVHRR NDVI数据集进行时间序列的扩展和完善。本研究通过建立MODIS NDVI与A... 植被是表征陆地生态系统的重要指标,气候变化对植被具有显著影响。虽然MODIS NDVI具有较高的精度,但时间序列长度有限,在年代际尺度的变化趋势研究中,仍然需要对AVHRR NDVI数据集进行时间序列的扩展和完善。本研究通过建立MODIS NDVI与AVHRR NDVI逐月线性回归模型,生成了长时间序列(1981-2013年)NDVI数据集;并以NDVI作为植被活动的指标,分析研究了近33年来西北干旱区的植被动态变化。结果表明:1)MODIS NDVI与LTDR NDVI数据具有较好的线性相关性,两者之间线性回归模型的决定系数均在0.7以上;2)近33年以来,西北干旱区的植被活动均呈现出增强的态势,其中稀疏植被区的植被活动在持续增强,植被整体状况在好转,而草地区的植被活动较为稳定,并未出现较大的变化;3)西北干旱区的气候呈现出暖湿化的特点,植被活动对气候变化较为敏感,NDVI与年平均温度和年降水量之间呈显著相关关系(P<0.05)。 展开更多
关键词 植被指数 遥感监测 西北干旱区 AVHRR MODIS
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1982~2001年间中国干旱发生时空特征的遥感分析 被引量:10
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作者 齐述华 牛铮 +1 位作者 王军邦 王长耀 《土壤学报》 CAS CSCD 北大核心 2006年第3期376-382,共7页
利用1982~2001年NOAA-AVHRR旬合成的光谱植被指数和NOAA-AVHRR第4和第5通道亮温计算的陆地表面温度资料,利用水分亏缺指数(WDI)作为干旱评价指标,分析了全国近20 a干旱时空分布特征,并对近20 a来各月份发生干旱的频率进行了分析.提... 利用1982~2001年NOAA-AVHRR旬合成的光谱植被指数和NOAA-AVHRR第4和第5通道亮温计算的陆地表面温度资料,利用水分亏缺指数(WDI)作为干旱评价指标,分析了全国近20 a干旱时空分布特征,并对近20 a来各月份发生干旱的频率进行了分析.提取全国雨量观测站点的水分亏缺指数和20 a干旱发生频次,分析了它们与降水量的关系.研究结果表明:(1)我国地域辽阔,气候类型多样,干旱发生具有明显的时空差异.四川盆地属于冬春旱型;西北为常年干旱型;黄淮海平原为春夏旱型;西南青藏区为常年湿润型;华南为冬春旱型;(2)在年降水量少于500mm时,20 a平均降水量与20a平均水分亏缺指数和20a总干旱发生频次都呈明显线性关系,但在年均降水大于500mm时,水分亏缺指数及干旱发生频次与降水量关系都不显著,表明WDI可以很好地评价干旱胁迫的程度,但并不适宜评价湿润程度. 展开更多
关键词 干旱 遥感 水分亏缺指数 中国
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中国区域植被叶面积指数时空分布——机理模型模拟与遥感反演比较 被引量:47
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作者 黄玫 季劲钧 《生态学报》 CAS CSCD 北大核心 2010年第11期3057-3064,共8页
叶面积指数是表征植被冠层特征的重要参数,同时也是决定生态系统净初级生产力的重要因子,它对全球变化和生态系统碳循环研究具有重要意义。目前大范围的叶面积指数只能通过遥感反演和机理模型模拟获得,而通过这两种方法获取的叶面积指... 叶面积指数是表征植被冠层特征的重要参数,同时也是决定生态系统净初级生产力的重要因子,它对全球变化和生态系统碳循环研究具有重要意义。目前大范围的叶面积指数只能通过遥感反演和机理模型模拟获得,而通过这两种方法获取的叶面积指数都存在一定的不确定性。利用大气-植被相互作用模型(AVIM2)在0.1°×0.1°经纬度网格上模拟产生了中国区域叶面积指数并与两套使用不同遥感反演方法生成的叶面积指数在空间分布和季节变化特征方面进行了比较。通过比较说明中国区域植被叶面积指数分布主要受水分条件限制,整体呈现东南部高西北部低的趋势。中国区域植被生长的季节变化受季风影响显著,与气温及地表太阳辐射的季节变化趋势相一致。中国区域叶面积指数整体呈现夏季高、春秋季次之而冬季低的趋势。 展开更多
关键词 叶面积指数 AVIM2 遥感反演 样带 中国区域
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基于时间序列叶面积指数傅里叶变换的作物种植区域提取 被引量:25
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作者 王鹏新 荀兰 +2 位作者 李俐 解毅 王蕾 《农业工程学报》 EI CAS CSCD 北大核心 2017年第21期207-215,共9页
为了获取不同农作物的空间分布信息,以华北平原黄河以北地区为研究区域,利用Savitzky-Golay滤波对2014—2016年的时间序列叶面积指数(leaf area index,LAI)进行重构,进而应用一阶差分法和重构LAI的傅里叶变换的谐波特征对研究区域主要... 为了获取不同农作物的空间分布信息,以华北平原黄河以北地区为研究区域,利用Savitzky-Golay滤波对2014—2016年的时间序列叶面积指数(leaf area index,LAI)进行重构,进而应用一阶差分法和重构LAI的傅里叶变换的谐波特征对研究区域主要农作物冬小麦、玉米和棉花种植区域进行识别和提取,并对不同作物的识别精度进行验证。结果表明,基于Savitzky-Golay滤波重构的LAI能够去除由云、大气等因素造成的LAI骤降的影响,重构LAI曲线平滑且符合作物的生长规律特征。研究区域2014—2016年作物识别的总体精度均大于80.00%,2015年达到87.08%,冬小麦-夏玉米、春玉米、棉花和单季夏玉米的识别精度分别为92.50%、80.00%、85.00%和82.50%,表明利用一阶差分法能够准确提取研究区域一年一季和一年两季作物种植区域。结合傅里叶变换方法和作物物候信息能够有效地识别不同作物的种植区域,进而获取研究区域主要农作物的分布信息。该研究可为研究区域主要作物的长势监测及产量估测预测提供参考。 展开更多
关键词 作物 遥感 提取 面积 叶面积指数 傅里叶变换 Savitzky-Golay滤波 华北平原
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中国农业现代化发展水平的定量综合评价 被引量:130
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作者 蒋和平 黄德林 《农业现代化研究》 CSCD 北大核心 2006年第2期87-91,共5页
采用多指标综合分析方法,建立中国农业现代化指标体系评价模型,对中国农业现代化发展水平进行了定量评价。结果显示:1980—2003年,总体上,中国农业现代化水平呈上升趋势,农业现代化区域发展总体水平表现为东部最高,中部次之,西部最低。
关键词 中国农业现代化 综合指数法 发展水平 综合评价
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