Suburbanization and Subcentering of Population in Beijing Metropolitan Area:A Nonparametric Analysis

This study focuses on the suburbanization and subcentering of population and examines the nature of spatial restructuring in terms of the population distribution in the Beijing metropolitan area.Instead of the classic density function approach,we employ the nonparametric analysis to characterize the spatial pattern of population densities in the Beijing metropolitan area and identify the suburban subcenters.Our findings suggest that the population has spread with rapid urban growth in the Beijing metropolitan area,and the compact urban form has been replaced by a more dispersed polycentric spatial distribution.However,compared with the decentralization of western cities,the spatial extent of the decentralization of population in the Beijing metropolitan area is quite limited.The rapid growth of population in the near suburbs has expedited the sprawl of the central city,with a larger central agglomeration of population dominating the metropolitan area.In this sense,the spatial pattern of the Beijing metropolitan area is still characterized by the continuous compactness.However,our findings do provide the evidence that the city has been turning to a polycentric structure.We find significant population subcenters have emerged in the suburbs of Beijing since the 1980s.But the polycentricity emerged in the Beijing metropolitan area is very different by nature from that observed in Western cities.The subcenters emerged are adherent to the development scheme planned for the city,so it can be referred to as the so called 'planned polycentricity'.

Diurnal Variations of Summer Precipitation in the Beijing Area and the Possible Effect of Topography and Urbanization

The present study examined the diurnal variations of summer precipitation in the Beijing area by usingsubdaily precipitation and wind observations. A combined effect of topography and urbanization on thecharacteristics of diurnal variations was suggested. It was shown that stations located in the plain areaexhibited typical night rain peaks, whereas those in the mountainous area exhibited clear afternoon peaks ofprecipitation diurnal variations. The precipitation peaks were associated with wind fields around the Beijingarea, which were found to be highly modulated by mountain-valley circulation and urban-country circulation.The lower-tropospheric wind exhibited a clear diurnal shift in its direction from north at 0800 LST to southat 2000 LST, which reflected mountain-valley circulation. The transitions from valley to mountain windand the opposite generally happened after sunset and sunrise, respectively, and both occurred earlier for thestations located closer to mountains. By comparing the diurnal variations of precipitation at stations in anortheast suburb, an urban area, and a southwest suburb, it was revealed that the northeast suburb grouphad the highest normalized rainfall frequency, but the southwest group had the lowest from late afternoon tolate evening. On the contrary, in the early morning from about 0200 to 1000 LST, the southwest group andurban group had the highest normalized rainfall frequency. This pattern might originate from the combinedeffects of mountain-valley topography and urbanization.

Sensitivity Assessment and Optimization Strategy of Climatic Environment in Central Urban Area of Beijing

As one of the methods of urban environmental assessment,sensitivity assessment of urban climatic environment can accurately reflect the problem areas of current urban climate and built environment through visual means,and help cities to carry out sustainable transformation and renewal in the stock era to optimize the living environment.Taking the central urban area of Beijing as the research object,the sensitivity of climatic environment was evaluated by meteorological data and built environment element data.The results showed that the distribution of sensitive units showed a centrifugal radiation pattern of"high in the center and low in the periphery".Block units with high climate sensitivity were mostly concentrated in Xicheng District and Dongcheng District,accounting for 93%of the total number of units.Further research showed that complex built environment and lack of elements to regulate climatic environment were the main reasons for the poor local climatic environment in the region with high climate sensitivity.Finally,a comprehensive evaluation of the remolding capacity,renewal potential and future development intensity of different grades of climate sensitive units was given.The results will provide scientific reference for urban renewal and reconstruction under climatic and environmental changes,so as to promote urban sustainable development and improvement of living environment.

Walkability Assessment of Microclimatic Environments of Six Typical Communities in Central Urban Area of Beijing from the Perspective of the Elderly

Community walking space is the most used space in residents’daily life,such as commuting and walking,and is also the most basic type of space for outdoor activities.The microclimatic environment of walking space not only affects the health status of residents,but also determines the service effi ciency of outdoor public space.Based on actual measurement and simulation of microclimatic environment,the status quo of walkability of microclimatic environments in six typical communities is evaluated by quantitative methods,and general problems and optimization suggestions are put forward,in order to provide new ideas for future community environment transformation.

Measurement of Urban Economic Gravity of China’s Three Major Agglomerations and Its Implications for the Coordinated Development of the Beijing-Tianjin-Hebei Region

This paper adopts the perspective of urban economic linkage and the modified urban economic gravity model to conduct a comparative analysis of the economic gravity among cities in China’s three major urban agglomerations,including the Beijing-Tianjin-Hebei region,the Yangtze River Delta,and the Pearl River Delta.The results show that,despite the ever-tightening economic linkages among cities in the urban agglomerations,the development of the Beijing-Tianjin-Hebei region falls behind that of the Yangtze River Delta and the Pearl River Delta in terms of coordination,closeness,and balance.The economic linkages among cities in the Beijing-Tianjin-Hebei region are not as cohesive as they could be and display a significant“siphon effect”through Beijing and Tianjin as well as a prominently unidirectional economic flow.This study suggests that efforts should be put into directing the orderly flow of resources from Beijing and Tianjin to cities in Hebei and promoting a balanced economic flow among cities,thus facilitating the coordination of regional development.

Using Impervious Surfaces to Detect Urban Expansion in Beijing of China in 2000s

The change of impervious surface area(ISA) can effectively reveal the gradual process of urbanization and act as a key index for monitoring urban expansion. Experiencing rapid growth of the built environment in the 2000 s, urban expansion of Beijing has not been fully characterized through ISA. In this study, Landsat TM images of Beijing in 2001 and 2009 were obtained, and the eight-year urban expansion process in Beijing was analyzed using the ISA extracted by means of the vegetation-imperious surface-soil(V-I-S) model. From the spatial variation in ISA, the ring structure of urban expansion in Beijing was significant during the study period, with decreasing urban density from the city center to the periphery. In the ring road analysis, the most dramatic changes of ISA were found between the fifth ring and the sixth ring. This area has experienced the most new residential development, and is currently the main source of urban expansion. The typical profile lines revealed the directional characteristics of urban expansion. The east-west profile was the most urbanized axes in Beijing, while ISA change in the east-north profile was more significant than in the other five profiles. Moreover, the transition matrix of ISA levels revealed an increase in urban density in the low density built areas; the Moran′s I index showed a clear expansion of the central urban area, which spread contiguously; and the standard deviational ellipse indicated the northeast was the dominant direction of urban expansion. These findings can provide important spatial control guidelines in the next round of national economic and social development planning, overall urban and rural planning, and land use planning.

The diurnal and seasonal characteristics of urban heat island variation in Beijing city and surrounding areas and impact factors based on remote sensing satellite data

Based on the land surface temperature (LST), the land cover classification map,vegetation coverage, and surface evapotranspiration derived from EOS-MODIS satellite data, and by the use of GIS spatial analytic technique and multivariate statistical analysis method, the urban heat island (UHI) spatial distribution of the diurnal and seasonal variabilities and its driving forces are studied in Beijing city and surrounding areas in 2001. The relationships among UHI distribution and landcover categories, topographic factor, vegetation greenness, and surface evapotranspiration are analyzed. The results indicate that: (i) The significant UHI occur in Beijing city areas in the four seasons due to high heat capacity and multi-reflection of compression building, as well as with special topographic features of its three sides surrounded by mountains,especially in the summer. The UHI spatial distribution is corresponding with the urban geometry structure profile. The LST difference is approximately 4-6℃ between Beijing city and suburb areas, comparatively is 8- 10℃ between Beijing city area and outer suburb area in northwestern regions. (ii) The UHI distribution and intensity in daytime are different from nighttime in Beijing city area, the nighttime UHI is obvious. However, in the daytime, the significant UHI mainly appears in the summer, the autumn takes second place, and the UHI in the winter and the spring seem not obvious. The surface evapotranspiration in suburb areas is larger than that in urban areas in the summer, and high latent heat exchange is evident, which leads to LST difference between city area and suburb area. (iii) The reflection of surface landcover categories is sensitive to the UHI, the correlation between vegetation greenness and UHI shows obviously negative.The scatterplot shows that there is the negative correlation between NDVI and LST (R2 = 0.6481).The results demonstrate that the vegetation greenness is an important factor for reducing the UHI,and large-scale construction of greenbelts can considerably reduce the UHI effect.

Accuracy assessments and uncertainty analysis of spatially explicit modeling for land use/cover change and urbanization:A case in Beijing metropolitan area

Spatially explicit modeling plays a vital role in land use/cover change and urbanization research as well as resources management;however,current models lack proper validation and fail to incorporate uncertainty into the formulation of model predictions.Consequently,policy makers and the general public may develop opinions based on potentially misleading research,which fails to allow for truly informed decisions.Here we use an uncertainty strategy of spatially explicit modeling combined with the series statistic of Kappa index for location and quantity to estimate the uncertainty of future predications and to determine model accuracy.We take the Beijing metropolitan area as an example to demonstrate the uncertainty in extrapolations of predictive land use change and urban sprawl with spatially explicit modeling at multiple resolutions.The sensitivity of scale effects is also discussed.The results show that an improvement in specification of location is more helpful in increasing accuracy as compared to an improvement in the specification of quantity at fine spatial resolutions.However,the spatial scale has great effects on modeling accuracy and correct due to chance tends to increase as resolution becomes coarser.The results allow us to understand the uncertainty when using spatially explicit models for land-use change or urbanization estimates.

京津冀建设中国式现代化先行区、示范区的理论逻辑与路径选择

基于建设中国式现代化先行区、示范区的战略使命,回顾了京津冀协同发展的演进历程及阶段特征,识别了京津冀协同发展的新要求;依托区域经济发展机制分析了京津冀协同发展面临的经济社会环境变化,结合京津冀创新实践构建了“疏建结合的要素投入”“内涵集约的要素组合”“地方品质导向的要素聚集”“多节点网络化的要素布局”“深化协同的要素治理”五个方面的京津冀协同发展理论框架。在此基础上,从根植国家经济社会发展宏观背景、立足区域发展现实基础、遵循区域经济发展规律出发,围绕着经济发展、协同开放、空间布局、政府治理、共同富裕和生态改善提出了京津冀建设中国式现代化先行区、示范区的路径构想。

An efficient method of evaluating large scale urban residential skylight environment and an empirical study of Beijing main area

A good skylight environment in urban residential areas is an important component of a healthy city,and has always been highly valued.With the rapid development of new-type urbanization,the density of buildings continues to increase,and megacities have entered the stage of stock transformation.An effective method for evaluating the skylight environment of large-scale urban residential areas is urgently needed.However,there is still a lack of empirical research methods and cases of large-scale residential skylight environment.In this regard,this article takes the megacity Beijing as the research object,and proposes an efficient analysis method of residential skylight environment that integrates multiple real-world data at city scale.In terms of data,it collects and integrates 3D data of urban-scale building space and residential boundary data;in terms of algorithm,Sky View Factor(SVF)is used as the evaluation index of residential skylight environment,and an efficient analysis method of urban-scale skylight environment based on cloud parallel simulation is realized.Through analysis,it is found that:(1)the average SVF value of Beijing residential area is 61%,which means that its skylight quality is in general level;(2)the skylight environment of Beijing residential area is distributed in a circle,and there are 4 types of skylight environment quality residential areas;(3)The skylight environment of Beijing residential area is relatively weakly related to the distance from the residential area to the city center and the average height of the residential buildings,and is closely related to the plot volume ratio,the residential building density and the shading from surrounding buildings.The highlight of this study lies in the empirical research on the skylight environment of mega-city residential areas that incorporates multiple real data for the first time,which can promote the study of skylight environment on a city scale and provide a reference for the updating of Beijing’s residential daylight environment.

时空感知:基于历史地理信息的北京西北郊聚落空间解析

城郊聚落处于城乡环境长时段的互动影响中,积存形成多元历史文化要素,促进城市建成区的蔓延或更新,并支持与历史建成环境的融合,其空间演变是探索聚落当代发展的重要支撑点。利用历史地理信息(HGI)的方法,在梳理历史、识别资源、明确价值的前提下,对北京西北郊聚落发展作历史演变规律探索,总结出北京西北郊聚落具有城乡统筹、中心吸引、多元共生的发展特征,并在多尺度层级中呈现耦合向关联转向、地缘向业缘适配、廊道对要素牵引等演变倾向。综上,时空感知下的聚落空间解析为探索地域聚落的在地性发展路径提供有效指导。

基于参与式地理信息系统的城市绿地生态系统文化服务评价——以北京市核心区为例

【目的】目前中国的城市建设发展模式已逐渐转变为注重提升城市文化软实力和城市精神的新模式。北京市核心区作为全国文化中心建设的核心承载区,评价其生态系统文化服务(cultural ecosystem services,CES)有助于促进城市绿地文化功能建设及体系完善,提升居民福祉。【方法】引入参与式地理信息系统(participatory geographic information system,PGIS),对被调查者感知到的文化功能、服务价值进行参与式互动制图,实现北京市核心区生态空间中CES感知点的空间落位,并进行空间分析。【结果】揭示了不同人群对CES的差异化感知、CES感知点的空间分布特征及各类CES之间的空间自相关性。【结论】为北京市核心区及其他区域城市绿地的更新优化提供参考意见,探索以文化为根基的城市创新发展之路。

多圈层视角下北京市轨道交通发展策略研究——基于与东京都市圈的对比分析

为更好支撑新发展阶段下北京市轨道交通的规划建设,以东京都市圈与北京市的轨道交通线网为研究对象,在多尺度分析和总结东京都市圈轨道交通发展经验的基础上,梳理东京都市圈和北京市在8 km以内、8~15km、15~30km、30~50km和50km以外5个圈层的轨道交通线网规模及不同圈层的轨道交通服务水平,形成相关量化指标,并通过指标对比,总结东京都市圈和北京市不同圈层轨道交通的特征差异,最后以此为据提出北京市未来的轨道交通发展建议,以期推动北京市轨道交通高质量、可持续发展。

绿色空间景观格局对热环境的影响研究——以北京市平原地区为例

在城市高密度建设、热环境恶化的背景下,绿色空间格局对调控热环境、保障健康人居环境起重要作用。研究基于北京市平原地区的Landsat遥感数据,运用监督分类、景观生态学理论及统计分析方法,揭示了绿色空间格局与平原地区热环境的耦合关系。结果显示:(1)MSPA分析显示总体降温效果,支线>桥接>边缘>核心>孔隙>环道>孤岛;(2)核心、环道、边缘型绿色空间随着绿量的减少和破碎化,其降温效果逐年下降;(3)孤岛型绿色空间的降温效果逐年增加,桥接和支线型绿色空间的降温效果则更为稳定;(4)北京市平原地区的线状绿色空间在近二十年发挥的作用大于面状、点状。研究可为北京市应对气候变化、优化平原地区的绿色空间格局提供理论参考。

聚焦同城化 加快推动首都都市圈发展的思考

顺应城镇化发展演变规律,推动同城化发展是构建现代化首都都市圈的内在要求,有利于拓展北京发展空间和促进内部功能重整,提升周边交界地区发展水平,增强中心城市辐射带动作用。近年来,环京周边地区与北京的经济社会联系持续增强,重点区域合作不断深化,同城化发展具有较好基础,但与长三角等同城化发展成熟的地区相比,其同城化水平还有很大差距,存在交通通勤能力较弱、产业协同能力有限、要素流通不畅和公共服务不均衡等问题,可以从强化设施联通、增进服务共通、促进产业协同、深化制度创新等方面入手,加快推动首都都市圈同城化发展。

北京市PM_(2.5)中水溶性有机碳污染特征研究

于2019年的1月1日—12月31日采集了315个细颗粒物(PM_(2.5))样品,用于研究北京大气气溶胶中水溶性有机碳(WSOC)的特点和来源。结果表明:2019年北京城区WSOC平均质量浓度为4.58μg/m^(3),浓度范围为0.50~23.87μg/m^(3)。WSOC的质量浓度呈现了显著的季节差异,按照从大到小的顺序排列依次是冬季>秋季>春季>夏季。相关性分析结果表明在夏、秋季受到一次源和二次源的共同影响,而在春、冬季受到一次源的影响更大,在夏、秋季二次源影响高于春、冬季。在冬季WSOC受到燃煤的影响。

北京城市副中心及周边区域蓝绿空间景观格局及降温效应评估

科学评估北京城市副中心及周边区域建设不同阶段景观格局和热环境,对其今后的发展规划和相关政策制定具有重要意义。以北京城市副中心外围规划为基准稍作调整作为研究区,选取2016年、2018年、2020年和2022年共4期资源三号遥感影像数据,以及Google Earth Engine(GEE)中4年6月1日-9月30日的Landsat 8遥感影像数据,通过面向对象分类、地表温度反演、相关性分析方法定量分析不同时期的蓝绿空间景观格局以及蓝绿空间的降温效应。结果表明:(1)2016-2022年,研究区蓝空间的面积占比在保持稳定的同时逐渐增加,绿空间的面积占比先减少后增加;(2)2016-2022年,北京城市副中心及周边区域蓝绿空间景观格局中各斑块类型在景观中的分布越来越均衡;(3)2016-2022年间,地表温度均值呈“上升—下降—上升”的波动变化,蓝空间的地表温度最低,其次是绿空间,蓝空间和绿空间在一定程度上起到降温的作用;(4)提高聚集度、减少人类活动的割裂程度、减小空间破碎度均可提升蓝绿空间的降温效应。总体而言,北京城市副中心及周边区域建设使得蓝绿空间面积增加,景观格局分布更加均衡,蓝绿空间的降温效果较为明显。

Effect of urbanization on the winter precipitation distribution in Beijing area

According to the urbanization extent of Beijing area, and with 1980 as a turning point, the duration from 1961 to 2000 is divided into two periods: one is defined as the slow urbanization period from 1961 to 1980, and other one as the fast urbanization period from 1981 to 2000. Based on the 40-year’s precipi-tation data of 14 standard weather stations in Beijing area, the effect of urbanization on precipitation distribution is studied. It is found that there has been a noticeable and systematic change of winter precipitation distribution pattern between these two periods in Beijing area: in the slow urbanization period, the precipitation in the southern part of Beijing is more than that in the northern part; but in the fast urbanization period, the precipitation distribution pattern is reverse, i.e. the precipitation in the southern part is less than that in the northern part; But in other seasons, the precipitation distribution pattern did not change remarkably in general. The possible cause resulting in the change of winter precipitation distribution pattern, might be that with urban area extension, the effects of "urban heat island" and "urban dry island" become more and more intensified, and increase hydrometeors evapo-ration below precipitable cloud, and then cause less precipitation received on the ground surface in the downtown and the southern part. It is also noteworthy to further research why the precipitation distri-bution pattern does not change systematically in other seasons except winter after intense urbaniza-tion in Beijing area.

Numerical Simulation of Wind and Temperature Fields over Beijing Area in Summer

The non-hydrostatic mesoscale model MM5V3 is used to simulate the wind andtemperature fields of the atmospheric boundary layer over Beijing area in summer with the meshresolution of 1 km. The simulation results show that the numerical model can successfully simulatethe urban heat island effect and the wind and temperature fields which are affected by thecomplicated topography and urban heat island. The results show that: (1) the west area (from Haidianto Fengtai Districts) is always the high temperature center of Beijing, where the surfacetemperature is about 6 K higher than the other suburbs; and (2) due to the unique topography thewind of Beijing area during the daytime is southern anabatic wind and at the night is northernkatabatic wind. The results comparing well with the data from surface observation stations validatethe accuracy of the simulation.

Factors of spatial distribution of recreation areas in peri-urban Beijing

Based on the case study of peripheral urban areas in Beijing, this paper aims to identify the factors which will influence the spatial distribution of peri-urban recreation areas, by analyzing the collected data from questionnaires, online survey, documentation and field investigations （2007）. In order to achieve sound information, relevant data from different management departments, owners and land-use types involved in the case study area are collected. A sampling database for peri-urban recreation areas in Beijing is established, and GIS spatial analyses as well as statistic analyses are applied. The result indicates that spatial distribution of recreation areas is majorly influenced by four factors, e.g. tourism attractions and environmental conditions, policy and spatial governance, consumption demand and preference, land price and availability. Tourism attractions and environmental conditions are dominant factors for public recreation areas. Commercial recreation areas are highly related with accessibility. Agricultural recreation areas are usually attached to special farmlands near large-scaled scenic areas. Meanwhile, recreational business clusters have appeared in sub- urbs influenced by mass recreation market growth. Controlled by the land price, commercial recreation areas are differentiated on their scales and developing intensity. Policy and spatial governance have made arrangements of recreation areas more balancing and more hu- man-oriented. A peri-urban recreation area model is therefore established on the basis of this analysis, which can guide urban planning and designing, land-use planning and recreation resource development.