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Variations of Vegetation Phenology Extracted from Remote Sensing Data over the Tibetan Plateau Hinterland during 2000–2014

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Journal of Meteorological Research 2020年第4期34卷 786-797页

作者： Ya LIU Junbang WANG jinwei dong Shaoqiang WANG Hui YE Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural ResourcesChinese Academy of SciencesBeijing 100101 Key Laboratory of Watershed Geographic Sciences Nanjing Institute of Geography and LimnologyChinese Academy of SciencesNanjing 210008

How vegetation phenology responds to climate change is a key to the understanding of the mechanisms driving historic and future changes in regional terrestrial ecosystem productivity. Based on the 250-m and 8-day moderate resolution imaging spectroradiometer(MODIS) normalized difference vegetation index(NDVI) data for 2000-2014 in the Three-River Source Region(TRSR) of Qinghai Province, China, i.e., the hinterland of the Tibetan Plateau, we extracted relevant vegetation phenological information(e.g., start, end, and length of growing season) and analyzed the changes in the TRSR vegetation in response to climate change. The results reveal that, under the increasingly warm and humid climate, the start of vegetation growing season(SOS) advanced 1.03 day yr-1 while the end of vegetation growing season(EOS) exhibited no significant changes, which led to extended growing season length. It is found that the SOS was greatly affected by the preceding winter precipitation, with progressively enhanced precipitation facilitating an earlier SOS. Moreover, as the variations of SOS and its trend depended strongly on topography, we estimated the elevation break-points for SOS. The lower the elevations were, the earlier the SOS started. In the areas below 3095-m elevation, the SOS delay changed rapidly with increasing elevation;whereas above that, the SOS changes were relatively minor. The SOS trend had three elevation break-points at 2660, 3880, and 5240 m.

关键词： Three-River Source Region(TRSR) start of vegetation growing season(SOS) spatiotemporal change elevation climate change China

Quantifying the response of surface urban heat island to urbanization using the annual temperature cycle model

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Geoscience Frontiers 2022年第1期13卷 478-487页

作者： Huidong Li Yuyu Zhou Gensuo Jia Kaiguang Zhao jinwei dong Department of Geological and Atmospheric Sciences Iowa State UniversityAmes 50011USA Key Laboratory of Regional Climate-Environment for Temperate East Asia Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Ohio Agricultural Research and Development Center School of Environment and Natural ResourcesThe Ohio State UniversityWoosterOH 44691USA Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101

Urban heat island(UHI),driving by urbanization,plays an important role in urban sustainability under climate ***,the quantification of UHI’s response to urbanization is still challenging due to the lack of robust and continuous temperature and urbanization datasets and reliable quantification *** study proposed a framework to quantify the response of surface UHI(SUHI)to urban expansion using the annual temperate cycle *** built a continuous annual SUHI series at the buffer level from 2003 to 2018 in the Jing-Jin-Ji region of China using MODIS land surface temperature and imperviousness derived from *** then investigated the spatiotemporal dynamic of SUHI under urban expansion and examined the underlying ***,the largest SUHI interannual variations occurred in suburban areas compared to the urban center and rural ***,the increase in SUHI under urban expansion was more significant in daytime compare to *** found that the seasonal variation of SUHI was largely affected by the seasonal variations of vegetation in rural areas and the interannual variation was mainly attributed to urban expansion in urban ***,urban greening led to the decrease in summer daytime SHUI in central urban *** findings deepen the understanding of the long-term spatiotemporal dynamic of UHI and the quantitative relationship between UHI and urban expansion,providing a scientific basis for prediction and mitigation of UHI.

关键词： Urban heat island Urbanization Spatiotemporal dynamics Annual temperature cycle model Diurnal temperature range

Mapping paddy rice distribution using multi-temporal Landsat imagery in the Sanjiang Plain, northeast China

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Frontiers of Earth Science 2016年第1期10卷 49-62页

作者： Cui JIN Xiangming XIAO jinwei dong Yuanwei QIN Zongming WANG Department of Microbiology and Plant Biology Center for Spatial Analysis University of Oklahoma Norman OK 73019 USA Institute of Biodiversity Sciences Fudan University Shanghai 200433 China Northeast Institute of Geography and Agricultural Ecology Chinese Academy of Sciences Changchun 130102 China

Information of paddy rice distribution is essential for food production and methane emission calculation. Phenology-based algorithms have been uti- lized in the mapping of paddy rice fields by identifying the unique flooding and seedling transplanting phases using multi-temporal moderate resolution （500m to 1 km） images. In this study, we developed simple algorithms to identify paddy rice at a fine resolution at the regional scale using multi-temporal Landsat imagery. Sixteen Landsat images from 2010-2012 were used to generate the 30 m paddy rice map in the Sanjiang Plain, northeast China-one of the major paddy rice cultivation regions in China. Three vegetation indices, Normalized Difference Vegetation Index （NDVI）, Enhanced Vegetation Index （EVI）, and Land Surface Water Index （LSWI）, were used to identify rice fields during the flooding/transplanting and ripening phases. The user and producer accuracies of paddy rice on the resultant Landsat-based paddy rice map were 90% and 94%, respectively. The Landsat-based paddy rice map was an improvement over the paddy rice layer on the National Land Cover Dataset, which was generated through visual interpretation and digitalization on the fine-resolution images. The agricultural census data substantially underreported paddy rice area, raising serious concern about its use for studies on food security.

关键词： phenology flooding transplanting ripening,land use

The 2012 Flash Drought Threatened US Midwest Agroecosystems

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Chinese Geographical Science 2019年第5期29卷 768-783页

作者： JIN Cui LUO Xue XIAO Xiangming dong jinwei LI Xueming YANG Jun ZHAO Deyu College of Urban and Environment Liaoning Normal UniversityDalian116029China Department of Microbiology and PlantBiology Center for Spatial AnalysisUniversity of OklahomaNormanOK73019USA Ministry of Education Key Laboratory ofBiodiversity Science and Ecological Engineering Institute of Biodiversity ScienceFudan UniversityShanghai200433China KeyLaboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academyof SciencesBeijing100101China

In the summer of 2012, the US Midwest, the most productive agricultural region in the world, experienced the most intense and widespread drought on record for the past hundred years. The 2012 drought, characterized as ‘flash drought’, developed in May with a rapid intensification afterwards, and peaked in mid-July. ~76% of crop region and 60% of grassland and pasture regions have been under moderate to severe dry conditions. This study used multiple lines of evidences, i.e., in-situ AmeriFlux measurements, spatial satellite observations, and scaled ecosystem modeling, to provide independent and complementary analysis on the impact of 2012 flash drought on the US Midwest vegetation greenness and photosynthesis carbon uptake. Three datasets consistently showed that 1) phenological activities of all biomes advanced 1–2 weeks earlier in 2012 compared to the other years of 2010–2014;2) the drought had a more severe impact on agroecosystems(crop and grassland) than on forests;3) the growth of crop and grassland was suppressed from June with significant reduction of vegetation index, sun-induced fluorescence(SIF) and gross primary production(GPP), and did not recover until the end of growing season. The modeling results showed that regional total GPP in 2012 was the lowest(1.76 Pg C/yr) during 2010–2014, and decreased by 63 Tg C compared with the other-year mean. Agroecosystems, accounting for 84% of regional GPP assimilation, were the most impacted by 2012 drought with total GPP reduction of 9%, 7%, 6%, and 29% for maize, soybean, cropland, and grassland, respectively. The frequency and severity of droughts have been predicted to increase in future. The results imply the importance to investigate the influences of flash droughts on vegetation productivity and terrestrial carbon cycling.

关键词： food security terrestrial carbon cycling eddy covariance Vegetation Photosynthesis Model sun-induced fluorescence(SIF)

Divergent effects of climate change on cropland ecosystem water use efficiency at different elevations in southwestern China

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Journal of Geographical Sciences 2022年第8期32卷 1601-1614页

作者： TAO Jian ZHU Juntao ZHANG Yangjian dong jinwei ZHANG Xianzhou School of Public Administratio n Shand ong Tech no logy and Business UniversityYantai 264005ShandongChina Nagqu Alpine Grassland Research Station Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources ResearchCASBeijing 100101China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchCASBeijing 100101China

Understanding climatic effects on cropland water use efficiency at different elevations is imperative for managing agricultural water and production in response to ongoing climate change in climate-sensitive areas with complex topography, such as southwestern China. We investigated climatic effects on cropland water use efficiency in southwestern China at each 100-m elevation bin during 2001–2017. The maximum water use efficiency was 1.71 gC kg^(–1) H_2O for the 1900–1999 m elevation bin under the growing season temperature and precipitation of 14.58±0.32℃ and 965.40±136.45 mm, respectively. The water use efficiency slopes were dominated by the evapotranspiration slopes at elevations below 1999 m but were controlled by the gross primary productivity slopes at elevations above 2000 m. This difference was caused by the substantial responses of evaporation to climate change at lower elevations and the increased climatic sensitivity of gross primary productivity at higher elevations. In comparison to those at other elevations, croplands at lower elevations were more vulnerable to extreme drought because of the dominant role fluctuating evapotranspiration played in water use efficiency. The findings will improve cropland water management in the study area.

关键词： cropland water use efficiency southwestern China elevational gradient

The relationships between urban-rural temperature difference and vegetation in eight cities of the Great Plains

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Frontiers of Earth Science 2019年第2期13卷 290-302页

作者： Yaoping CUI Xiangming XIAO Russell B DOUGHTY Yaochen QIN Sujie LIU Nan LI Guosong ZHAO jinwei dong Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions Henan UniversityKaifeng 475004China Department of Microbiology and Plant Biology Center for Spatial AnalysisUniversity of OklahomaNormanOK 73019USA Ministry of Education Key Laboratory of Biodiversity Science and Ecological Engineering Institute of Biodiversity ScienceFudan UniversityShanghai 200438China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China

Interpreting the relationship between urban heat island (UHI) and urban vegetation is a basis for understanding the impacts of underlying surfaces on UHL The calculation of UHI intensity (UHII) requires observations from paired stations in both urban and rural *** to the limited number of paired meteorological stations,many studies have used remotely sensed land surface temperature,but these time-series land surface temperature data are often heavily affected by cloud cover and other *** factors,together with the algorithm for inversion of land surface temperature,lead to accuracy problems in detecting the UHII,especially in cities with weak *** on meteorological observations from the Oklahoma Mesonet,a world-class network,we quantified the UHII and trends in eight cities of the Great Plains,USA,where data from at least one pair of urban and rural meteorological stations were *** examined the changes and variability in urban temperature,UHII,vegetation condition (as measured by enhanced vegetation index,EVI),and evapotranspiration (ET).We found that both UHI and urban cold islands (UCI) occurred among the eight cities during 2000-2014 (as measured by impervious surface area).Unlike what is generally considered,UHII in only three cities significantly decreased as EVI and ET increased (p < 0.1),indicating that the UHI or UCI cannot be completely explained simply from the perspective of the underlying *** vegetative cover (signaled by EVI) can increase ET,and thereby effectively mitigate the *** study station clearly showed that the underlying surface or vegetation affects urban-rural temperature,and that these factors should be considered during analysis of the UHI effect over time.

关键词： urbanization evapotranspiration urban cold island background climate air temperature

Decoding the inconsistency of six cropland maps in China

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The Crop Journal 2024年第1期12卷 281-294页

作者： Yifeng Cui Ronggao Liu Zhichao Li Chao Zhang Xiao-Peng Song Jilin Yang Le Yu Mengxi Chen jinwei dong Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Department of Geographical Sciences University of MarylandCollege ParkMD 20740USA College of Grassland Science and Technology China Agricultural UniversityBeijing 100193China Ministry of Education Ecological Field Station for East Asian Migratory Birds Department of Earth System ScienceInstitute for Global Change StudiesTsinghua UniversityBeijing 100084China Ministry of Education Ecological Field Station for East Asian Migratory Birds Beijing 100084China Tsinghua University(Department of Earth System Science)-Xi’an Institute of Surveying and Mapping Joint Research Center for Next-Generation Smart Mapping Beijing 100084China Institute of Remote Sensing and Geographic Information System Peking UniversityBeijing 100871China Department of Forest and Conservation Sciences University of British ColumbiaVancouverBCV6T 1Z4Canada

Accurate cropland information is critical for agricultural planning and production,especially in foodstressed countries like *** widely used medium-to-high-resolution satellite-based cropland maps have been developed from various remotely sensed data sources over the past few decades,considerable discrepancies exist among these products both in total area and in spatial distribution of croplands,impeding further applications of these *** factors influencing their inconsistency are also *** this study,we evaluated the consistency and accuracy of six cropland maps widely used in China in circa 2020,including three state-of-the-art 10-m products(i.e.,Google Dynamic World,ESRI Land Cover,and ESA WorldCover)and three 30-m ones(i.e.,GLC_FCS30,GlobeLand 30,and CLCD).We also investigated the effects of landscape fragmentation,climate,and agricultural *** using a ground-truth sample revealed that the 10-m-resolution WorldCover provided the highest accuracy(92.3%).These maps collectively overestimated Chinese cropland area by up to 56%.Up to 37%of the land showed spatial inconsistency among the maps,concentrated mainly in mountainous regions and attributed to the varying accuracy of cropland maps,cropland fragmentation and management practices such as *** work shed light on the promotion of future cropland mapping efforts,especially in highly inconsistent regions.

关键词： Consistency and accuracy 10-and 30 m Cropland mapping Agricultural management China

English Speech Recognition and Multidimensional Pronunciation Evaluation

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教育研究前沿（中英文版） 2020年第3期10卷 184-188页

作者： jinwei dong Shaohui Li School of English Education Guangdong University of Foreign StudiesGuangzhou 510006China

As one of the four major skills in English learning,speaking is an important part in English learning which getting more and more *** study set out to improve the accuracy of speech recognition by applying speech recognition technology to the evaluation of English *** this basis,the study attempts to improve computer speech evaluation *** model employs indexes such as intonation,speech rate,rhythm and intonation,using multi-dimensional indicators as evaluation criteria to establish a more comprehensive and objective English speech evaluation *** learners can use the evaluation systems to guide their self-study,and the system can have a profound influence on the practice of teaching spoken English.

关键词： Spoken English Speech Recognition Pronunciation Evaluation

Comparison of three remotely sensed drought indices for assessing the impact of drought on winter wheat yield

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International Journal of Digital Earth 2020年第4期13卷 504-526页

作者： Jianxi Huang Wen Zhuo Ying Li Ran Huang Fernando Sedano Wei Su jinwei dong Liyan Tian Yanbo Huang Dehai Zhu Xiaodong Zhang College of Land Science and Technology China Agricultural UniversityBeijingPeople’s Republic of China Key Laboratory of Remote Sensing for Agri-Hazards Ministry of AgricultureBeijingPeople’s Republic of China CMA·Henan Key Laboratory of Agrometeorological Support and Applied Technique ZhengzhouPeople’s Republic of China Henan Institute of Meteorological Sciences ZhengzhouPeople’s Republic of China Department of Geographical Sciences University of MarylandCollege ParkMDUSA Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijingPeople’s Republic of China Department of Geography College of GeosciencesTexas A&M UniversityCollege StationTXUSA United States Department of Agriculture Agricultural Research ServiceCrop Production Systems Research UnitStonevilleMSUSA

Agricultural drought threatens food *** remote-sensing drought indices have been developed,but their different principles,assumptions and physical quantities make it necessary to compare their suitability for drought monitoring over large ***,we analyzed the performance of three typical remote sensing-based drought indices for monitoring agricultural drought in two major agricultural production regions in Shaanxi and Henan provinces,northern China(predominantly rain-fed and irrigated agriculture,respectively):vegetation health index(VHI),temperature vegetation dryness index(TVDI)and drought severity index(DSI).We compared the agreement between these indices and the standardized precipitation index(SPI),soil moisture,winter wheat yield and National Meteorological Drought Monitoring(NMDM)*** average,DSI outperformed the other indices,with stronger correlations with SPI and soil *** also corresponded better with soil moisture and NMDM *** jointing and grain-filling stages of winter wheat are more sensitive to water stress,indicating that winter wheat required more water during these ***,the correlations between the drought indices and SPI,soil moisture,and winter wheat yield were generally stronger in Shaanxi province than in Henan province,suggesting that remote-sensing drought indices provide more accurate predictions of the impacts of drought in predominantly rain-fed agricultural areas.

关键词： Agricultural drought remote sensing drought index winter wheat yield