Temporal-spatial characteristics of observed key parameters of snow cover in China during 1957–2009

Using observed snow cover data from Chinese meteorological stations, this study indicated that annual mean snow depth, Snow Water Equivalent (SWE), and snow density during 1957–2009 were 0.49 cm, 0.7 mm, and 0.14 g/cm³ over China as a whole, respectively. On average, they were all the smallest in the Qinghai-Tibetan Plateau (QTP), and were greater in northwestern China (NW). Spatially, the regions with greater annual mean snow depth and SWE were located in northeastern China including eastern Inner Mongolia (NE), northern Xinjiang municipality, and a small fraction of southwestern QTP. Annual mean snow density was below 0.14 g/cm³ in most of China, and was higher in the QTP, NE, and NW. The trend analyses revealed that both annual mean snow depth and SWE presented increasing trends in NE, NW, the QTP, and China as a whole during 1957–2009. Although the trend in China as a whole was not significant, the amplitude of variation became increasingly greater in the second half of the 20th century. Spatially, the statistically significant (95%-level) positive trends for annual mean snow depth were located in western and northern NE, northwestern Xinjiang municipality, and northeastern QTP. The distribution of positive and negative trends for annual mean SWE were similar to that of snow depth in position, but not in range. The range with positive trends of SWE was not as large as that of snow depth, but the range with negative trends was larger.     

2000年以来华北平原植被生产力和蒸散变化的归因分析（英文）

Quantifying the contributions of climate change and human activities to ecosystem evapotranspiration(ET)and gross primary productivity(GPP)changes is important for adaptation assessment and sustainable development.Spatiotemporal patterns of ET and GPP were estimated from 2000 to 2014 over North China Plain(NCP)with a physical and remote sensing-based model.The contributions of climate change and human activities to ET and GPP trends were separated and quantified by the first difference de-trending method and multivariate regression.Results showed that annual ET and GPP increased weakly,with climate change and human activities contributing 0.188 mm yr~(–2) and 0.466 mm yr~(–2) to ET trend of 0.654 mm yr~(–2),and–1.321 g C m~(–2) yr~(–2) and 7.542 g C m~(–2) yr~(–2) to GPP trend of 6.221 g C m~(–2) yr~(–2),respectively.In cropland,the increasing trends mainly occurred in wheat growing stage;the contributions of climate change to wheat and maize were both negative.Precipitation and sunshine duration were the major climatic factors regulating ET and GPP trends.It is concluded that human activities are the main drivers to the long term tendencies of water consumption and gross primary productivity in the NCP.     

1990-2015年中国山地城市的扩张特点及其驱动机制研究（英文）

Land expansion of mountain cities in China is not systematically studied yet.This study identified 55 major mountain cities at and above prefecture level,and analyzed the land expansion characteristics and driving forces,based on visually interpreted data from TM images in 1990,2000,2010 and 2015.From 1990 to 2015,total built-up land area of the mountain cities increased by 3.87 times,5.56%per year.The urban land growth was apparently accelerated after 2000,from 4.35%per year during 1990–2000 increased to 6.47%during 2000–2010 and 6.2%during 2010–2015.Compared to the urban population growth,the urban land expansion rate was 44% higher.As a result,the urban land area per capita increased,but it was still within the government control target,and also was much lower than the average of all cities in China.Urban development policy,changes to administrative divisions,GDP and population growth,and road construction were identified as the major driving forces of land expansion.Terrain conditions were not found a relevance to the urban land expansion rate during 1990–2015,but had a significant impact on the layout and shape,and also probably on the urban land efficiency.     

基于区域划分方法的中国人口分布格局及变化研究——从1953年到2010年（英文）

This study uses six censuses(1953, 1964, 1982, 1990, 2000, and 2010) at the county level since the foundation of the People's Republic of China to examine the changes of population density pattern in mainland China over time. Based on the Gini coefficient, the change of disparity in population density followed a "U-shaped" trend, i.e., decreasing during 1953–1982 and increasing during 1982–2010. The shrinking disparity in the pre-reform periods was largely attributable to various ill-conceived political movements, and the enlarging gap in population growth rates in the post-reform era reflected a natural outcome of urbanization, which will continue in the foreseeable future. In addition, this research employs a GIS-automated regionalization method, REDCAP, to uncover a natural demarcation line like the classic "Hu Line" that divides China into two regions of similar area sizes but a strong contrast in population. The results show that the regionalization-derived lines were largely consistent with the Hu Line over time. Therefore, the disparity between the high-density southeast and low-density northwest regions is likely due to differing physical environments that form a natural barrier. Any public policy to overcome this barrier at a large scale is destined to be a vain attempt.     

1961-2014年中国高温事件频率和强度的时空变化（英文）

In this study, we explored spatial patterns and the temporal trends in high-temperature events(HTEs) for the mainland of China during 1961–2014 based on a daily-maximum surface-air-temperature dataset of 494 stations and nonparametric trend detection methods. With three thresholds of 35°C(HTE35), 37°C(HTE37), and 40°C(HTE40), HTEs occurred in 82%, 71%, and 37% of the surveyed stations and showed an overall increasing trend in both frequency and intensity during 1961–2014. In northern and southeastern China, HTEs showed a significant increasing trend in both frequency and intensity, whilst a decreasing trend for both was observed in central China. Despite such regional heterogeneity, HTEs overwhelmingly presented three-phase characteristics in all three representative regions and throughout China; the phases are 1961–1980, 1980–1990, and 1990–2014. Both frequency and intensity of HTEs have strongly increased during 1990–2014 at 54.86%, 48.38%, and 23.28% of the investigated stations for HTE35, HTE37 and HTE40, respectively. These findings implied that HTEs adaptation should be paid further attention in the future over China because the wide spread distribution of HTEs and their increasing trends in both frequency and intensity during recent decades might pose challenges to the sustainability of human society and the ecosystem.     

The characteristics of oasis urban expansion and drive mechanism analysis: a case study on Ganzhou District in Hexi Corridor, China

Ganzhou District is an oasis city in the Zhangye Municipality of Gansu Province,China.Based on multi-temporal TM and ETM satellite remote sensing data in 1985,1996,2000,and 2012,and by using corrected figures of land use status over the same periods,the spatial area of Ganzhou District since 1985 was extracted with statistical methods,and urban spatial expansion was measured by quantitative research methods.The characteristics of spatial expansion of Ganzhou District were analyzed by urban expansion rate,expansion intensity index,compactness,fractal dimension,and the city center shift method.The results showed that the built-up area of Ganzhou District increased by 3.46 times during 1985–2012.The expansion in 1985–1996 was slow,during 1996–2000 it was rapid,and during 2000–2012 it was at a high speed.This city mainly expanded to the northeast and northwest.Government decision making had a decisive influence on urban expansion.Initially the expansion was uniform,but later the local transportation,economy,resources,population,and national policies factors had an obvious influence on urban expansion.     

1990–2010年中国土地覆被变化引起反照率改变的辐射强迫(英文)

Land cover change affects surface radiation budget and energy balance by changing surface albedo and further impacts the regional and global climate. In this article, high spatial and temporal resolution satellite products were used to analyze the driving mechanism for surface albedo change caused by land cover change during 1990–2010. In addition, the annual-scale radiative forcing caused by surface albedo changes in China's 50 ecological regions were calculated to reveal the biophysical mechanisms of land cover change affecting climate change at regional scale. Our results showed that the national land cover changes were mainly caused by land reclamation, grassland desertification and urbanization in past 20 years, which were almost induced by anthropogenic activities. Grassland and forest area decreased by 0.60% and 0.11%, respectively. The area of urban and farmland increased by 0.60% and 0.19%, respectively. The mean radiative forcing caused by land cover changes during 1990–2010 was 0.062 W/m2 in China, indicating a warming climate effect. However, spatial heterogeneity of radiative forcing was huge among different ecological regions. Farmland conversing to urban construction land, the main type of land cover change for the urban and suburban agricultural ecological region in Beijing-Tianjin-Tangshan region, caused an albedo reduction by 0.00456 and a maximum positive radiative forcing of 0.863 W/m2, which was presented as warming climate effects. Grassland and forest conversing to farmland, the main type of land cover change for the temperate humid agricultural and wetland ecological region in Sanjiang Plain, caused an albedo increase by 0.00152 and a maximum negative radiative forcing of 0.184 W/m2, implying cooling climate effects.     

Spatial and temporal variabilities of rainstorms over China under climate change

Rainstorms are one of the extreme rainfall events that cause serious disasters, such as urban flooding and mountain torrents. Traditional studies have used rain gauge observations to analyze rainstorm events, but relevant information is usually missing in gauge-sparse areas. Satellite-derived precipitation datasets serve as excellent supplements or substitutes for the gauge observations. By developing a grid-based rainstorm-identification tool, we used the Tropical Rainfall Measurement Mission(TRMM) Multi-satellite Precipitation Analysis(TMPA) time series product to reveal the spatial and temporal variabilities of rainstorms over China during 1998–2017. Significant patterns of both increasing and decreasing rainstorm occurrences were detected, with no spatially uniform trend being observed across the whole country. There was an increase in the area being affected by rainstorms during the 20-year period, with rainstorm centers shifting along the southwest–northeast direction. Rainstorm occurrence was found to be correlated with local total precipitation. By comparing rainstorm occurrence with climate variables such as the El Ni?o-Southern Oscillation and Pacific Decadal Oscillation, we also found that climate change was likely to be the primary reason for rainstorm occurrence in China. This study complements previous studies that used gauge observations by providing a better understanding of the spatiotemporal dynamics of China's rainstorms.     

1971-2000年青藏高原气候变化趋势

Trends of annual and monthly temperature, precipitation, potential evapotranspi- ration and aridity index were analyzed to understand climate change during the period 1971–2000 over the Tibetan Plateau which is one of the most special regions sensitive to global climate change. FAO56–Penmen–Monteith model was modified to calculate potential evapotranspiration which integrated many climatic elements including maximum and mini- mum temperatures, solar radiation, relative humidity and wind speed. Results indicate gen- erally warming trends of the annual averaged and monthly temperatures, increasing trends of precipitation except in April and September, decreasing trends of annual and monthly poten- tial evapotranspiration, and increasing aridity index except in September. It is not the isolated climatic elements that are important to moisture conditions, but their integrated and simulta- neous effect. Moreover, potential evapotranspiration often changes the effect of precipitation on moisture conditions. The climate trends suggest an important warm and humid tendency averaged over the southern plateau in annual period and in August. Moisture conditions would probably get drier at large area in the headwater region of the three rivers in annual average and months from April to November, and the northeast of the plateau from July to September. Complicated climatic trends over the Tibetan Plateau reveal that climatic factors have nonlinear relationships, and resulte in much uncertainty together with the scarcity of observation data. The results would enhance our understanding of the potential impact of climate change on environment in the Tibetan Plateau. Further research of the sensitivity and attribution of climate change to moisture conditions on the plateau is necessary.     

中国近期主要农业自然灾害的时空变化分析(英文)

China is a disaster prone country, and a comprehensive understanding of change of disasters is very important for China’s agricultural development. In this study, statistical techniques and geographic information system tools are employed to quantify the main agriculture disasters changes and effects on grain production in China during the period of 1990–2011. The results show that China’s grain production was severely affected by disasters including drought, flood, hail, frost and typhoon. The annual area covered by these disasters reached up to 48.7×106 ha during the study period, which accounted for 44.8% of the total sown area, and about 55.1% of the per unit area grain yield change was caused by disasters. In addition, all of the disasters showed high variability, different changing trends, and spatial distribution. Drought, flood, and hail showed significantly decreasing trends, while frost and typhoon showed increasing trends. Drought and flood showed gradual changes and were distributed across the country, and disasters became more diversified from north to south. Drought was the dominated disaster type in northern China, while flood was the most important disaster type in the southern part. Hail was mainly observed in central and northern China, and frost was mainly distributed in southern China. Typhoon was greatly limited to the southeast coast. Furthermore, the resilience of grain production of each province was quite different, especially in several major grain producing areas, such as Shandong, Liaoning, Jilin and Jiangsu, where grain production was seriously affected by disasters. One reason for the difference of resilience of grain production was that grain production was marginalized in developed provinces when the economy underwent rapid development. For China’s agricultural development and grain security, we suggest that governments should place more emphasis on grain production, and invest more money in disaster prevention and mitigation, especially in the major grain producing provinces.     

基于DEA的中国特大城市资源效率及其变化

利用DEA、Malmquist指数模型方法,对1990-2006年中国特大城市要素资源效率及其变化进行了深入的研究.城市效率研究显示,特大城市平均效率一般,只有少数城市达到了效率最优.进一步的分类研究发现:①东、中部地区特大城市综合效率一般要高于西部地区,呈现出与我国区域经济格局相似的特征;②纯技术效率与城市规模成弱负相关关系,即城市规模越大,城市纯技术效率越低;③城市规模与规模效率成一定的正相关关系,即城市规模越大,规模效率越高.城市效率变化研究显示,1990-2006年特大城市效率呈现弱改善趋势,但技术退步和生产率下降明显.其中1990-2000年全都呈上升趋势,而2000-2006年全都呈下降趋势.进一步的分类研究显示:①城市综合效率和生产率变化趋势是,东部沿海地区有一定提高,中西部地区下降,其中,西部地区下降最明显.②不同规模城市的综合效率变化表现为,特大城市提高,超大城市和巨型城市下降;③不同规模城市的生产率都呈现下降趋势;④不同规模城市的规模效率都呈上升趋势,存在随特大城市规模的增大,城市规模效率提高的趋势呈现递减的现象.     

中国东部城市旅游效率的空间特征——以沿海城市群为例(英文)

The traditional data envelopment analysis(DEA), bootstrap-DEA and Malmquist models are employed to measure different tourism efficiencies and their spatial characteristics of 61 cities in six coastal urban agglomerations in eastern China. The following conclusions are drawn.(1) The comprehensive efficiency(CE) of urban tourism using the bootstrap-DEA model is lower than the CE level using the DEA-CRS model, which confirms the significant tendency of the DEA-CRS model to overestimate results.(2) The geometric CE averages of urban tourism in the Yangtze River Delta(YRD) and the Pearl River Delta(PRD) have changed from ineffective to effective since 2000, the averages in the Beijing-TianjinHebei(BTH) and the Shandong Peninsula(SDP) have changed from ineffective to moderately effective since 2000, and those in the Central and Southern Liaoning(CSL) and the West Bank of Taiwan Strait(WBTS) have been ineffective since 2000.(3) The CE values of urban tourism in the PRD, the YRD, the BTH and the SDP have been slightly affected by the pure technical efficiency(PTE), whereas the CE values in the CSL and the WBTS have been slightly affected by the scale efficiency(SE) since 2000.(4) Spatially, the range of geometric averages of the total factor productivity(TFP) for the PRD, the YRD, the BTH, the SDP, the WBTS and the CSL has decreased sequentially, while the one for most cities in six urban agglomerations has exhibited a downward trend since 2000.(5) Collectively, the natural conditions, the economic policies and the tourism capital drive the SE change of urban tourism of the CSL and the WBTS. The tourism enterprises for increasing returns to scale and imitating innovative technology have an effect on the CE change of urban tourism in the BTH and the SDP. The tourism market competition drives the PTE change of urban tourism in the PRD and the YRD. Although the PTE and the SE of urban tourism in six coastal urban agglomerations suffer from uncertain events, the CE maintained overall sound momentum since 2000.     

Spatial characteristics of development efficiency for urban tourism in eastern China: A case study of six coastal urban agglomerations

The traditional data envelopment analysis（DEA）, bootstrap-DEA and Malmquist models are employed to measure different tourism efficiencies and their spatial characteristics of 61 cities in six coastal urban agglomerations in eastern China. The following conclusions are drawn.（1） The comprehensive efficiency（CE） of urban tourism using the bootstrap-DEA model is lower than the CE level using the DEA-CRS model, which confirms the significant tendency of the DEA-CRS model to overestimate results.（2） The geometric CE averages of urban tourism in the Yangtze River Delta（YRD） and the Pearl River Delta（PRD） have changed from ineffective to effective since 2000, the averages in the Beijing-TianjinHebei（BTH） and the Shandong Peninsula（SDP） have changed from ineffective to moderately effective since 2000, and those in the Central and Southern Liaoning（CSL） and the West Bank of Taiwan Strait（WBTS） have been ineffective since 2000.（3） The CE values of urban tourism in the PRD, the YRD, the BTH and the SDP have been slightly affected by the pure technical efficiency（PTE）, whereas the CE values in the CSL and the WBTS have been slightly affected by the scale efficiency（SE） since 2000.（4） Spatially, the range of geometric averages of the total factor productivity（TFP） for the PRD, the YRD, the BTH, the SDP, the WBTS and the CSL has decreased sequentially, while the one for most cities in six urban agglomerations has exhibited a downward trend since 2000.（5） Collectively, the natural conditions, the economic policies and the tourism capital drive the SE change of urban tourism of the CSL and the WBTS. The tourism enterprises for increasing returns to scale and imitating innovative technology have an effect on the CE change of urban tourism in the BTH and the SDP. The tourism market competition drives the PTE change of urban tourism in the PRD and the YRD. Although the PTE and the SE of urban tourism in six coastal urban agglomerations suffer from uncertain events, the     

2000年以来中国东部四大沿海城市群城市旅游业发展效率的综合测度与时空特征

以城市群地级以上城市为生产单元,采用传统DEA、Bootstrap-DEA纠偏和Malmquist指数模型测算和分析中国东部4 大沿海城市群城市旅游业发展效率与时空特征。结果表明：①由传统DEA模型测度的城市群城市旅游业综合效率及其分解效率值均要高于Bootstrap-DEA纠偏模型测度后的效率值,表明了传统模型测度存在明显高估倾向的问题。② 2000 年以来4 大城市群主要直辖市、省会城市和核心城市旅游业投入资源利用综合水平呈持续良好态势;同时,长三角和珠三角城市旅游业平均投入资源利用综合水平呈无效向良好转变,京津冀和山东半岛城市旅游业则呈无效向中等转变。③ 2000 年以来珠三角和长三角城市旅游业综合效率受纯技术效率的影响程度略强于规模效率,而京津冀和山东半岛城市旅游业则反之。④ 2000年以来4 大城市群大多数城市提高幅度大但趋于下降,珠三角和长三角主要直辖市、省会城市和核心城市全要素生产率变化提高幅度略高于京津冀和山东半岛;同时,珠三角、长三角、京津冀和山东半岛城市旅游业平均全要素生产率提高幅度呈依次下降态势。     

The Spatial Restructuring of Population in Metropolitan Beijing: Toward Polycentricity in the Post-Reform ERA

Based on data from the third (1982), fourth (1990), and fifth (2000) Population Census of China, this research examines the changing patterns of population distribution in the Beijing metropolitan area in the post-reform era. In the mid-1980s, China launched a series of urban land use reforms aimed toward achieving a market economy. A direct impact of these reforms in Beijing was the restructuring of land uses, evidenced by the relocation of central-city residents to the suburbs to make room for commercial development. This residential suburbanization trend emerged during the 1980s and accelerated in the 1990s. Population change rates varied significantly across subdistricts, and variation was much greater in the 1990s than in the 1980s, indicating an increasingly diverse set of growth trajectories across metropolitan Beijing over time. Various population density functions are tested. The population density pattern is best characterized by a monocentric model in 1982, a dual-centered model in 1990, and a seven-centered model in 2000. This transition in Beijing's urban form toward polycentricity is similar to trends in most Western cities.     

2000-2013年中国城市群经济绩效动态实证分析——基于DEA和Malmquist生产率指数法

在全球化和新型城镇化大背景下,城市群是辐射面最广、潜力最大、活力最强的核心增长极,但其高速成长背后是各类要素的大量投入,客观评估城市群经济绩效对于推动中国城镇化持续健康发展意义深远。在总结既有研究的基础上,选取中国13个典型城市群为样本,以2000-2013年为研究时段,采用资本、土地、劳动、科技和经济五大要素长时间序列数据,在全要素生产率(TFP)分析框架下,通过数据包络分析方法(DEA)静态评价时间截面的城市群投入产出效率,进而运用Malmquist生产率指数法动态分析城市群TFP年际变化,探讨其时空格局和内在演化机制。研究发现：城市群经济绩效进步明显,但空间分布仍不均衡;科技进步贡献的滞后在一定程度上抵消了通过规模扩张和资源配置优化带来的正效应,只有长三角、珠三角和京津冀三大城市群初步实现依靠科技进步促进发展,表明各城市群所处发展阶段和动力机制差异显著。据此,提出针对不同地区、不同发展阶段城市群的发展策略。     

环渤海地区城市旅游业发展效率时空特征及其演化阶段——以三大城市群为例

以环渤海地区京津冀、山东半岛和辽东半岛三大城市群地级以上城市为单元,采用数据包络分析和全要素生产率指数模型测算和分析三大城市群城市旅游业发展效率及其时空特征分解效率差异及其影响因素的演化阶段。结果表明：①2000 年以来京津冀和山东半岛城市群城市旅游业平均投入资源利用综合水平呈无效向中等转变,而辽东半岛城市群始终处于无效状态,各城市群主要直辖市、省会城市和核心城市旅游业投入资源利用综合水平呈无效向中等转变;②2000 年以来京津冀和山东半岛城市群城市旅游业综合效率受纯技术效率的影响和制约程度略强于规模效率,而辽东半岛城市群则反之;③2000 年以来环渤海地区三大城市群城市旅游业平均全要素生产率变化呈依次下降态势,且大多数城市提高幅度大但趋于下降,京津冀和山东半岛城市群主要直辖市、省会城市和核心城市全要素生产率变化提高幅度明显高于辽东半岛城市群。④环渤海地区三大城市群城市旅游业发展效率分别受旅游投资、旅游技术和旅游市场因素、旅游产品和旅游技术因素、旅游资源、旅游政策和旅游项目（产品）因素的影响,各自处于技术创新阶段、技术学习阶段和规模主导阶段。     

中国大都市区的界定和发展研究——基于第六次人口普查数据的研究

借鉴都市区概念,采用“六普”城乡统计口径,以区、县为基本单元,利用人口密度、城镇化率等指标界定了128个大都市区。其次,对2000~2010年中国大都市区人口规模结构和空间分布的特征及变动进行了研究。从规模结构上看,以大都市区人口表征的中国城市规模分布符合位序规模法则,且属于较为分散的类型,但斜率q从2000年的0.787提高到2010年的0.891,显示都市区的规模分布趋向集聚,且高等级都市区仍有一定发展空间。从空间分布上看,东部是中国大都市区的主要分布地带,且人口有进一步向该地区集聚的趋势,并形成了三大都市区连绵地区;中部地区都市区数量增加较多,但人口比重有所下降;西部地区大都市区发展最为滞后,都市区极化现象十分突出。最后就中国大都市区的发展提出了建议。     

Change and continuity of income divide in the American Southeast: A metropolitan scale analyses, 2000–2014

Changing racial/ethnic diversity along with economic growth have also drawn renewed public attention to growing income inequality and lack of economic well-being in the American society. This paper investigates one element of contemporary inequality – the income divide between the richest and the poorest population groups in the metropolises of the U.S. Southeast. This paper examines income divide across southern U.S. metropolises in 2000 and 2014, their change during 2000–2014, their variation across major races/ethnicities, and their relationships with important metropolitan characteristics such as diversity, intermixing, socio-economic status and built-environment attributes. Cartographic, ranking/matrix, and correlations analyses suggest that the largest, most diverse, most segregated, and those with a greater presence of better educated are the most income divided metropolises, whereas the small-to-mid-sized metropolises, with lesser educated population are less divided. The income divide has increased during 2000–2014 in a majority of these metropolises, and for all races/ethnicities, even though Whites and Asians are relatively better-off compared to overall population whereas Blacks and Hispanics lag behind.     

中国地级以上城市工业创新效率空间格局研究

以中国288个地级以上城市为研究对象,运用2008年第二次全国经济普查工业创新活动数据,综合考察城市工业创新效率的空间格局及其影响因素。首先,从投入和产出两方面构建了中国城市工业创新效率评价体系,运用DEA包络分析方法,从规模效率和纯技术效率两个维度对城市工业创新技术效率进行分析。然后,以聚类分析划分了3类工业创新效率城市,总结工业创新效率模式的空间特征,并分析了影响空间格局的原因。研究发现：中国城市工业创新效率呈现东强西弱,阶梯状减弱的总体空间格局,工业创新规模效率和纯技术效率的空间特征并不重合;全国尺度上,工业创新效率城市的空间分布与人口密度“黑河-腾冲”线的分布基本一致,区域尺度上,城市间呈现“核心-边缘”空间结构;城市工业创新效率空间格局受到工业发展基础与工业创新能力影响,提高城市工业创新效率关键在于提升工业创新中人力资本要素和优化工业创新投入规模。