基于时间序列建模的城市热岛时间尺度成分分离方法与应用

城市热岛效应是全球与区域气候变化研究中的焦点问题。基于2001—2012年较长时间序列的北京市MODIS地表温度产品及相关NDVI和反射率产品,给出地表温度时间序列构建方法。基于站点气象观测资料进行的精度验证表明地表温度时间序列构建方法可行,并最终给出城市热岛强度的量化方案。研究选取统计学中X-11-ARIMA时间序列建模方法,分离并分析城市热岛强度时间序列的结构性成分。分析发现,以平均城乡温差为指标的北京城市热岛强度季节性特征明显,与城乡土地利用状况、季节性地表覆盖、地物热特性以及气候因子等联系密切。趋势—循环特征与城市扩张速度及入选城市区域面积相关。以已发生城市热岛区域城乡平均温差为指标的北京城市热岛强度趋势—循环特性在12年间表现平稳。时间序列建模分析提取出不规则变动成分,为定量研究偶然因素对城市热岛的影响提供了可能。     

近十年淮南矿区地表热环境时空演变分析

地表温度是描述陆表过程和反映地表特征的重要参数。研究矿区地表温度的时空演变特征,对于理解煤矿开采活动对矿区生态环境的影响具有重要意义。淮南矿区是我国东部典型的高潜水位煤矿区,为了探究该区域地表温度的时空异质性与开采扰动的关系,利用2008—2018年5期Landsat影像进行地表温度的反演和下垫面信息提取,结合热力景观格局指数和城市热岛比例指数的计算,分析近十年来淮南矿区地表热环境的时空演变特征。结果表明:淮南矿区地表温度分布格局及其变化与下垫面结构及其变化密切相关。2008—2018年间,淮南矿区地表温度总体以中温区为主,其次是次低温和次高温区,高温区和低温区面积及其占比相对较低。由于城镇和矿井建设,以及煤矿开采产生的煤矸石堆积和开采沉陷积水,建设用地和水域面积不断增加,植被面积不断减少,相应的低温区、次高温和高温区增长,中温和次低温区减少,总体上城市热岛比例指数不断增加,热岛效应不断加剧;低温区斑块破碎度和复杂度不断减小,优势度不断增大。其他温度级斑块破碎度和复杂度,景观团聚程度和连通性,多样性和均匀度变化分为2008—2013、2013—2015和2015—2018三个阶段,其中2013—2015年人类干扰强度较大,斑块破碎度和复杂度增大,景观团聚程度和连通性,多样性和均匀度减小。研究成果为淮南矿区生态环境的恢复治理和城市产业规划提供了科学依据。      

北京城市热岛效应的数值试验研究

采用数值模拟方法定量分析不同下垫面条件对于北京的城市风场、温度场等的影响,探讨北京城市热岛的形成机理和可能的改善途径。采用区域大气模拟系统MM5,模拟和分析了2000年秋季北京的城市热岛状况。结果显示,MM5模式能较好地模拟北京城市热岛现象,成功再现了城市高温中心及城市热岛环流。MM5模式与陆面过程模型Noah LSM的耦合能在很大程度上改善对热岛效应的模拟。     

Evaluation of urban heat island effect in Turkey

Recently, the rate of urbanisation has accelerated due to increasing population density which causes unexpected environmental disturbances and problems. One of the major problems encountered to date is the change in the land use/cover (LULC) structure. Increasing the impervious surface cover has changed microclimatic properties of urbanised areas by altering their thermal characteristics. One of the most important problems facing urban planning today is the phenomena known as the urban heat island (UHI), which is largely due to the changing the character of LULC. In this study, to create a national picture of the UHI structure in Turkey, seven cities, namely Istanbul, Bursa, Ankara, Izmir, Gaziantep, Erzurum and Trabzon, each located in different climatic regions of Turkey, were investigated. The Gaussian fitting technique was applied to characterise the UHI effect in the seven cities in the study. An original contribution of the current study was that the rural reference temperature surface was automatically determined by a proposed algorithm including the automatic masking of input data, as well as the application of iterative Gaussian low-pass filtering during the fitting procedure. Within this context, the daytime and nighttime surface urban heat island (SUHI) effect was modelled and temporally analysed from 1984 to 2011 for all the sub-regions using remote sensing techniques. Furthermore, atmospheric UHI was also investigated using the mobile transect method. The findings from this study suggest that UHI is a major environmental problem in urbanised areas, both atmospheric UHI and SUHI were detected in all cities in the study area, and this problem was found to have rapidly increased from 1984 to 2011. Finally, as inferred from the multiple regression results, it can be concluded that the UHI problem in Turkey might have resulted from the altered LULC structure, as well as anthropogenic pressure on and interference in city planning geometries.     

基于土地集约利用水平的城市热岛效应影响因子分析

利用乌鲁木齐市1990年8月6日、2001年7月11日和2013年7月4日三期热红外遥感数据,定量反演亮度温度,利用均值-标准差法对温度进行分级后评价城市热岛效应时间变化特征:1990、2001、2013年3个时段,乌鲁木齐市最大热岛强度分别为11.48℃,12.06℃和14.01℃;加权平均热岛强度分别为1.033℃,1.603℃,1.236℃;城市热岛比例指数分别为0.1054,0.3945和0.4328;乌鲁木齐市城市热岛效应在平均水平上呈现先增强、后减弱的趋势,最大热岛强度、热岛比例指数均增加,城市已初步形成区域内的"热岛",城市高温区温度将继续上升且面积存在扩展趋势.利用PSR模型构建指标体系对城市土地集约利用水平进行评价,在同时段内乌鲁木齐市城市土地集约利用水平和协调性均在提高.从评价结果出发,通过相关分析,得出基于土地集约利用的城市热岛效应影响因子包括:人口密度、建成区绿地覆盖率、地均国民生产总值、人均建设用地面积、人均道路铺装面积、地均固定资产投资,这些因子涵盖了经济、社会、环境三个方面.     

Vertical extension of the urban <Emphasis Type="Italic">heat island</Emphasis> above Moscow

The vertical extension of the urban “heat island” (UHI) has been studied on the basis of long-term data of contact air temperature measurements at three places for the example of Moscow. The existence of steady thermal anomaly related to the city in the form of a UHI in the surface layer at any time of the day and also the existence of a cold layer over it at heights higher than 100 m at night were confirmed. The mean daily altitudinal extension of this anomaly is approximately 300 m.     

Local warming of groundwaters caused by the urban heat island effect in Istanbul, Turkey

The urban heat island (UHI) is a result of urbanization, causing local microclimatologic changes such as increase in ambient temperature. Factors causing the UHI effect are anthropogenic energy release, energy absorption by concrete, tarmac structures and traffic, although the main factor is the replacement of vegetation with man-made structures. These factors cause heating of not only local air but also subsurface and groundwater. Observations of groundwater temperatures from the urban, southern part of Istanbul (Turkey) and the rural, northern part of Istanbul revealed that the urban groundwater temperatures were 3.5°C higher than the rural. Urbanization is a direct consequence of improvements in technology and modern life. However, this comes at the cost of an ever-increasing demand for energy. Exploitation of low-enthalpy geothermal energy is an attractive alternative to fossil fuel based energies. From the environmental point of view, clean and cheap energy is the most preferable, with heat pumps being the best choice for recovery purposes. Usage of elevated groundwater temperature in the heat pumps in urban areas increases the efficiency of the heat pump system and yields more thermal energy than that of rural groundwater. This system may be applicable to Istanbul.     

基于RS与GIS的北京市热岛研究

基于普适性单通道算法，利用2005年5月6日的TM数据反演北京市区的实际地表温度。在此基础上，分析了北京市区的热环境特征、热岛分布的位置。运用GIS空间分析工具，分析了地表温度与地形特征和地表覆盖类型之间的关系。结果表明，北京市热岛分布具有环状和带状分布特征，高程较低处和坡度较小处更容易形成热岛中心，不同地表覆盖类型的热特征具有显著的差异。     

Atlanta’s urban heat island under extreme heat conditions and potential mitigation strategies

The urban heat island (UHI), together with summertime heat waves, foster’s biophysical hazards such as heat stress, air pollution, and associated public health problems. Mitigation strategies such as increased vegetative cover and higher albedo surface materials have been proposed. Atlanta, Georgia, is often affected by extreme heat, and has recently been investigated to better understand its heat island and related weather modifications. The objectives of this research were to (1) characterize temporal variations in the magnitude of UHI around Metro Atlanta area, (2) identify climatological attributes of the UHI under extremely high temperature conditions during Atlanta’s summer (June, July, and August) period, and (3) conduct theoretical numerical simulations to quantify the first-order effects of proposed mitigation strategies. Over the period 1984–2007, the climatological mean UHI magnitude for Atlanta-Athens and Athens-Monticello was 1.31 and 1.71°C, respectively. There were statistically significant minimum temperature trends of 0.70°C per decade at Athens and −1.79°C per decade at Monticello while Atlanta’s minimum temperature remained unchanged. The largest (smallest) UHI magnitudes were in spring (summer) and may be coupled to cloud-radiative cycles. Heat waves in Atlanta occurred during 50% of the years spanning 1984–2007 and were exclusively summertime phenomena. The mean number of heat wave events in Atlanta during a given heat wave year was 1.83. On average, Atlanta heat waves lasted 14.18 days, although there was quite a bit of variability (standard deviation of 9.89). The mean maximum temperature during Atlanta’s heat waves was 35.85°C. The Atlanta-Athens UHI was not statistically larger during a heat wave although the Atlanta-Monticello UHI was. Model simulations captured daytime and nocturnal UHIs under heat wave conditions. Sensitivity results suggested that a 100% increase in Atlanta’s surface vegetation or a tripling of its albedo effectively reduced UHI surface temperature. However, from a mitigation and technological standpoint, there is low feasibility of tripling albedo in the foreseeable future. Increased vegetation seems to be a more likely choice for mitigating surface temperature.     

Development of a parameterization for simulating the urban temperature hazard using satellite observations in climate model

Urban surface temperature is hazardously higher than surrounding regions (so-called urban heat island effect UHI). Accurately simulating urbanization-induced temperature hazard is critical for realistically representing urban regions in the land surface-atmosphere climate system. However, inclusion of urban landscapes in regional or global climate models has been overlooked due to the coarse spatial resolution of these models as well as the lack of observations for urban physical properties. Recently, National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) Moderate Resolution Imaging Spectroradiometer (MODIS) observations illustrate important urban physical properties, including skin temperature, surface albedo, surface emissivity, and leaf area index, It is possible to identify the unique urban features globally and thus simulate global urban processes. An urban scheme is designed to represent the urban-modified physical parameters (albedo, emissivity, land cover, roughness length, thermal and hydraulic properties) and to include new, unique physical processes that exist in urban regions. The urban scheme is coupled with National Center for Atmospheric Research (NCAR) Community Land Model Version 2 (CLM2) and single column coupled NCAR Community Atmosphere Model CAM2/CLM2 to assess the mechanisms responsible for UHI. There are two-steps in our model development. First, satellite observations of albedo, emissivity, LAI, and in situ observed thermal properties are updated in CLM2 to represent the first-order urban effects. Second, new terms representing the urban anthropogenic heat flux, storage heat flux, and roughness length are calculated in the model. Model simulations suggest that human activity-induced surface temperature hazard results in overlying atmosphere instability and convective rainfall, which may enhance the possibility of urban flood hazard.

西安都市圈道路网络化对景观格局的影响

在快速城市化过程中,道路网络快速扩张对区域生态景观的分割、隔离、破坏等是导致生态景观过程与格局演变的重要原因。研究道路网络化对景观格局的影响可为快速城市化地区生态、道路建设和区域可持续发展规划提供参考。本文以西安都市圈为例,利用GIS和RS技术,基于西安都市圈TM遥感影像和Arcgis 10.1、Fragstats 4.2软件平台,通过构建道路网空间指数,定量评价了路网空间结构和景观格局变化,并从空间上分析了道路网络化对景观格局的影响。结果表明:1)1985—2015年,西安都市圈路网发育不断成熟,基本呈现以西安市区为中心、空间指数向四周递减(除杨陵区和阎良区外)且东高西低的趋势。2)随着城市化进程的不断推进,西安都市圈景观呈现多样化、复杂化和破碎化。其中:园地、林地和建设用地规模扩大,景观聚集度上升;耕地、水域及滩涂景观破碎化程度不断加深。3)30年间,高等级道路的修建、低等级道路的不断完善以及市内环路打通等,使得西安都市圈路网逐渐完善,景观优势度下降,破碎化程度上升,形状趋于规则化。此外,路网发育的程度不同对不同地类的影响各不相同:路网成熟的区域,建设用地面积较多,形状较规则,呈聚集状态,林地面积较少,且零星分布,破碎化程度较高;道路结构简单的区域,林地聚集成片,聚集度较高,耕地、水域及滩涂在路网空间指数各等级影响域内均呈现破碎化状态,且形状较不规则。     

Heat wave risk assessment and mapping in urban areas: case study for a midsized Central European city,Novi Sad (Serbia)

Risk assessment and mapping methodologies for heat waves as frequently occurring hazards in central and southeastern Europe were applied in this study, and the impact of heat waves on the mortality of urban populations was determined as part of the assessment. The methodology for conducting the heat wave risk assessment is based on European Commission’s Guidelines for Risk Assessment and Mapping. The Novi Sad (Serbia) urban area was studied during summer 2015, which was one of the hottest summers in the last few decades. In situ air temperature measurements from urban stations and mortality of urban populations were used. Nocturnal urban heat island (UHI) intensity values between the various built-up zones and natural surrounding areas were used for the hazard level calculation. Temperature data from 9 p.m. to 5 a.m. were used because during the night, the UHI intensity reached its maximum values. The average daily number of deaths by LCZs was used to define the impact level of the vulnerability index. Calculations for both hazard levels were completed during two intensive heat waves (in July and August 2015) when it was expected that there may be a high level of risk. The results and maps show that the urban area is complex, and the heat wave risk on the population is not uniform. The most densely built-up areas (LCZs 2, 5 and 6) have very high or high risk values that are influenced by a higher rate of mortality. The obtained results and maps can be used by local authorities to prevent and mitigate climate-related hazards, for medical institutions as well as urban planners and for ancillary local, regional or national services. According to these results, the local authorities could define hot spots where they can place medical and rescue teams and install points with water supplies, etc.     

Responses of water quality to land use in riparian buffers: a case study of Huangpu River,China

Along with the continuous urbanization process, massive riparian buffers are developed to satisfy the increasing demands for flood protection and economic growth. Such changes of land use types and landscape patterns pose a significant challenge to the protection of the eco-system of urban rivers. This research concentrates on revealing the potential relation between the water quality of the urban river and land characteristics including land use types and landscape patterns of the riparian area and discusses if the relationship varies with spatial scales. The study area of this research are the 800 m riparian buffer of the six river water quality monitoring sections along Huangpu River. Based on the long-term monthly collection data of six monitoring points in Huangpu River, Shanghai, China, and the land use data of 100 m downstream of 1 km upstream of the monitoring point. Using landscape indicators, GIS spatial analysis, and statistical methods, the responses of land use and landscape patterns to water quality in different scales are obtained. Results show that: (1) Urban Land (UL) and Agricultural Land (AL) have an enormous negative contribution to each buffer, which is the primary non-point source pollution and influencing factor. (2) The active contribution of Wetland (WL) and Forestry Land (FL) is the most significant in the small range buffer of 0–200 m. (3) The negative effect of Industrial Land (IL) on water quality is only significant in the small buffer. (4) The effect of landscape pattern on water quality is more significant on the large spatial scale than the small scale. At the same time, this paper extends the conclusion to discuss the land use of the 800 m buffer zone of Huang River by using point to the area, proving that the research result is helpful for the political decision of urban management and provides suggestions for the land optimization of riparian buffers.

     

Dynamics of land use/cover changes and the analysis of landscape fragmentation in Dhaka Metropolitan, Bangladesh

Rapid urban expansion due to large scale land use/cover change, particularly in developing countries becomes a matter of concern since urbanization drives environmental change at multiple scales. Dhaka, the capital of Bangladesh, has been experienced break-neck urban growth in the last few decades that resulted many adverse impacts on the environment. This paper was an attempt to document spatio-temporal pattern of land use/cover changes, and to quantify the landscape structures in Dhaka Metropolitan of Bangladesh. Using multi-temporal remotely sensed data with GIS, dynamics of land use/cover changes was evaluated and a transition matrix was computed to understand the rate and pattern of land use/cover change. Derived land use statistics subsequently integrated with landscape metrics to determine the impact of land use change on landscape fragmentation. Significant changes in land use/cover were noticed in Dhaka over the study period, 1975–2005. Rapid urbanization was manifested by a large reduction of agricultural land since urban built-up area increased from 5,500?ha in 1975 to 20,549?ha in 2005. At the same time, cultivated land decreased from 12,040 to 6,236?ha in the same period. Likewise, wetland and vegetation cover reduced to about 6,027 and 2,812?ha, respectively. Consequently, sharp changes in landscape pattern and composition were observed. The landscape became highly fragmented as a result of rapid increase in the built-up areas. The analysis revealed that mean patch size decreased while the number of patches increased. Landscape diversity declined, urban dominance amplified, and the overall landscape mosaics became more continuous, homogenous and clumped. In order to devise sustainable land use planning and to determine future landscape changes for sound resource management strategies, the present study is expected to have significant implications in rapidly urbanizing cities of the world in delivering baseline information about long term land use change and its impact on landscape structure.     

50余年来岩溶山地近郊村域土地利用与景观格局演变——以贵州省清镇市王家寨地区为例

选取贵州省清镇市近郊村域王家寨地区为研究对象,在GIS支持下,利用该区域1963年、1982年、2005年、2010年和2015年5期土地利用图形数据叠加分析,提取出研究区50余年来的土地利用/覆盖信息,并结合相应的社会经济统计数据,分析了其驱动力因子,其结果表明:(1)1963—2015年间,土地覆盖类型的总体变化为高被草地和平坝旱耕地明显减少,低被草地、农村居民点、工矿用地、公路用地面积大幅增加,其中,平坝旱耕地有向经济效益更高的土地利用方式转变的趋势;（2）景观格局演变的总体趋势是:自1963年起,斑块数量、斑块密度持续增加,到2015年呈下降趋势,而最大斑块指数逐年减小,形状趋于不规则,同时,近50年景观的多样性指数持续增加;（3）区内土地利用/覆盖和景观格局呈阶段性变化,从1963年到2005年,坡地土地利用活动较强,2005年后,平地土地利用强度增加、农业逐渐转型、聚落持续扩展;（4）区内土地利用及景观格局的变化主要受经济、人口和政策因素的影响。      

黑龙江省漠河地区土地覆被与地表温度时空变化特征研究

以我国高纬度多年冻土区漠河县城区及郊区862 km²的区域为研究对象,基于RS和GIS技术对该区地表覆被变化和地表温度进行研究。结果表明：地表类型和地表温度反演结果与现场比对结果一致;从1988年到2015年,经过火灾后重建和城镇化发展,建设用地面积增加了11.33 km²;以2015年为例,冬季由于积雪覆盖,有79.02%的区域无植被覆盖,夏季有80.91%的区域为高植被覆盖。冬季地表温度和高程具有高度相关性,高程每升高100 m,地表温度平均升高2.27℃,表明该区地表温度也存在显著的逆温现象。该区城镇热岛效应全年存在,城镇区域地表温度高于全区平均值,夏季最显著,最高温差可达6.37℃。地表温度与NDVI具有明显的负相关关系;不同土地利用类型地表温度由低到高的顺序为水体-林地-草地-裸地-建筑用地。     

城区与郊区土体湿度监测与对比分析——以南京市为例

由城市化进程改变的城市空间热环境对城区土体湿度产生了重要影响。为了了解城区与郊区土体湿度的差异,以南京市为例,分别在城区、郊区建立了土体湿度监测站,分析2009年6月1日至2010年6月7日南京城区、郊区地下1 m范围内裸土、草地及混凝土覆盖环境下土体湿度的时空演化特征。研究结果表明,南京城区土体湿度总体上小于郊区,存在显著的城市土体"干岛效应",年平均干岛强度为-7.4%。在时间尺度上,1月的干岛强度最小,为-2.1%;7月最大,达到-20.5%。在空间尺度上,郊区土体湿度随深度增加而增大,城区土体则无明显规律。在不同地面覆盖环境下,城区、郊区土体湿度变化规律不同:城区裸土环境下土体湿度日变化明显,而草地及混凝土下的土体湿度日变化相对较小,3种地面覆盖环境的年均土体湿度变化规律为草地(19.0%)<混凝土(26.4%)<裸土(29.5%);郊区3种地面覆盖环境下土体湿度日变化区间及变化频率均比城区大,且年均土体湿度为混凝土(27.4%)<草地(34.7%)<裸土(36.2%)。最后,分析了造成城区、郊区土体湿度差异的原因。     

Observation and analysis of the urban heat island effect on soil in Nanjing, China

The heat island effect in urban meteorology has received significant attention in the recent years. In order to investigate the heat island effect on urban soil, two observation stations were built, respectively, in an urban area and a rural area of Nanjing city, China. The temperatures of underground soil (0?C300?cm depth) were recorded continuously for 1?year from June 2009 to June 2010. The data show that the urban soil temperature is generally higher than the rural soil temperature, and reveal an obvious heat island effect in urban soil with average intensity of 2.02°C over the 1-year period. The intensity varies between days, months and seasons: the daily urban heat island intensity (UHII) of soil ranges from 0.37°C to 3.98°C; the monthly UHII of soil ranges from 1.34°C (November) to 3.05°C (July); the order of seasonal UHII is summer (2.45°C)?>?winter (2.03°C)?>?spring (1.63°C)?>?autumn (1.53°C). The temperature data indicate that the maximum influence depth of daily synoptic events on the subsurface temperature is approximately 60?cm; the UHII generally increases with increasing depth. In addition to soil temperature, the temporal?Cspatial variation of soil moisture in a 100?cm profile depth was also investigated in this study. It is found that the moisture content of urban soil is generally lower than that of rural soil, which reveals an obvious dry island effect with average intensity of ?7.2% over the 1-year period; the maximum single-day urban dry island intensity (UDII) in soil is ?28.0%; the maximum average monthly UDII is ?19.1%, observed in July; the seasonal UDII shows a tendency of summer (?13.8%)?>?spring (?6.3%)?>?autumn (?5.2%)?>?winter (?3.7%). In profile, soil moisture content generally increases with increasing depth, and the maximum UDII is ?25.8% at 40?cm depth. In addition, the large-scale measurement results of 600 general points also confirm that the heat island and dry island effects are exist in urban soil.     

基于遥感夜间灯光数据的大连城市用地扩张的空间特征分析

为揭示大连城市用地扩张的空间分布特征,基于DSMP/OLS夜间灯光数据提取1998—2013年大连地域边界,并得到各地区的灯光阈值及地域边界分区统计面积。通过计算不同时期不同区域的城市用地增长景观格局指数,研究该市16年来的城市用地扩张方向、强度和空间景观格局变化,以揭示大连20年来城市用地扩张的空间分布特征。结果表明,城市用地扩张主要集中在沙河口区、中山区和西岗区,并以其为中心向甘井子区、旅顺口区、金州区等区域扩张。城市用地空间格局总体基本稳定,受地理条件、空间距离、经济发展和政策指引等因素的影响,城市用地扩张在不同方向上差异化显著。研究成果可作为大连城市规划的依据。     

Effects of land use change on landscape pattern of the Manas River watershed in Xinjiang, China

The mechanism of interaction between land use change and landscape pattern is pivotal in research concerning global environmental change. Quantitative evaluation of land use change that has resulted from excessive land development and its impact on landscape pattern are important for sustainable utilization of local land resources. The study area was the Manas River watershed, a typical watershed in an arid area. The present study evaluated the influence of long-term land use change on the landscape pattern; the findings are valuable for economic development and environmental protection. The processes for land use change and changes in landscape pattern were reconstructed and analyzed for data in topographic maps dated 1962 and in remote sensing images taken in 1976, 1989, 1999 and 2008 using mathematical models and landscape metrics. The results indicate significant changes in land use over the past 50 years, with increases in the areas of cultivated land and construction land, and a significant decrease in unused land and woodland areas; grassland and water resources first increased and then tended to decrease over this time. The comprehensive index of land use change is 0.55, indicating an unbalanced, one-way transition in the study area. Landscape fragmentation and diversity increased and landscape dominance decreased; in other words, differences between landscapes decreased. The changes resulted in a significant tendency toward diversity and fragmentation of the landscape. Therefore, large-scale intensive agricultural development can reduce the negative influence of land use change on the landscape pattern.