城市发展对中国华北区域极端温度事件的影响(英文)

The regional changes of daily temperature extremes in North China caused by urbanization are studied further from observed facts and model estimates on the basis of homogenized daily series of maximum and minimum temperature observations from 268 meteorological stations, NCEP/DOE AMIP-Ⅱ reanalysis data(R-2), and the data of simulations by regional climate model(RegCM3). The observed facts of regional warming on long time scales are obtained by analyzing the indices of temperature extremes during two time periods of 1961–2010 and 1951–2010. For urbanization effect, the contributions to decreases in annual and winter diurnal temperature range(DTR) are 56.0% and 52.9%, respectively, and increases in the lowest minimum temperature(TNn) are 35.7% and 26.2% by comparison of urban and rural observations. Obtained by R-2 data with observations for contrast, on the other hand, increase in the number of annual warm nights(TN90p) contributed by urbanization is 60.9%. And observed facts of regional warming in daily temperature extremes are also reflected in the simulations, but what difference is urbanization progress at rural areas in North China would be prominent in the next few years relative to urban areas to some extent from model estimates.     

长江三角洲城市带扩展对区域温度变化的影响

Based on non-radiance-calibrated DMSP/OLS nighttime light imagery from 1992 to 2003, urban land area statistical data, meteorological data and land surface temperature data retrieved by MODIS and NOAA/AVHRR data, the influence of urbanization on regional cli- matic trend of temperature in the Yangtze River Delta (YRD) was analyzed. Conclusions are as follows: 1) There is a significant urbanization process from 1992 to 2003 in the YRD. Four city clusters of Nanjing–Zhenjiang–Yangzhou, Suzhou–Wuxi–Changzhou, Shanghai and Hangzhou Bay form a zigzag city belt. The increase rate of annual mean air temperature in city-belt is 0.28–0.44℃/10a from 1991 to 2005, which is far larger than that of non-city-belt. 2) The urban heat island (UHI) effect on regional mean air temperature in different seasons is summer>autumn>spring>winter. 3) The UHI intensity and the urban total population logarithm are creditably correlated. 4) The UHI effect made the regional annual mean air temperature increased 0.072℃ from 1961 to 2005, of which 0.047℃ from 1991 to 2005, and the annual maximum air temperature increased 0.162℃, of which 0.083℃ from 1991 to 2005. All these indicating that the urban expansion in the YRD from 1991 to 2005 may be regarded as a serious climate signal.     

Impact of urban expansion on regional tempera-ture change in the Yangtze River Delta

Based on non-radiance-calibrated DMSP/OLS nighttime light imagery from 1992 to 2003, urban land area statistical data, meteorological data and land surface temperature data retrieved by MODIS and NOAA/AVHRR data, the influence of urbanization on regional cli-matic trend of temperature in the Yangtze River Delta (YRD) was analyzed. Conclusions are as follows: 1) There is a significant urbanization process from 1992 to 2003 in the YRD. Four city clusters of Nanjing–Zhenjiang–Yangzhou, Suzhou–Wuxi–Changzhou, Shanghai and Hangzhou Bay form a zigzag city belt. The increase rate of annual mean air temperature in city-belt is 0.28–0.44℃/10a from 1991 to 2005, which is far larger than that of non-city-belt. 2) The urban heat island (UHI) effect on regional mean air temperature in different seasons is summer>autumn>spring>winter. 3) The UHI intensity and the urban total population logarithm are creditably correlated. 4) The UHI effect made the regional annual mean air temperature increased 0.072℃ from 1961 to 2005, of which 0.047℃ from 1991 to 2005, and the annual maximum air temperature increased 0.162℃, of which 0.083℃ from 1991 to 2005. All these indicating that the urban expansion in the YRD from 1991 to 2005 may be regarded as a serious climate signal.     

Effects of urbanization on daily temperature extremes in North China简

The regional changes of daily temperature extremes in North China caused by ur- banization are studied further from observed facts and model estimates on the basis of ho- mogenized daily series of maximum and minimum temperature observations from 268 mete- orological stations, NCEP/DOE AMIP- Ⅱ reanalysis data （R-2）, and the data of simulations by regional climate model （RegCM3）. The observed facts of regional warming on long time scales are obtained by analyzing the indices of temperature extremes during two time periods of 1961-2010 and 1951-2010. For urbanization effect, the contributions to decreases in an- nual and winter diurnal temperature range （DTR） are 56.0% and 52.9%, respectively, and increases in the lowest minimum temperature （TNn） are 35.7% and 26.2% by comparison of urban and rural observations. Obtained by R-2 data with observations for contrast, on the other hand, increase in the number of annual warm nights （TN90p） contributed by urbaniza- tion is 60.9%. And observed facts of regional warming in daily temperature extremes are also reflected in the simulations, but what difference is urbanization progress at rural areas in North China would be prominent in the next few years relative to urban areas to some extent from model estimates.     

20世纪80年代以来全球气温变化特征

The study of temperature change in major countries of the world since the 1980 s is a key scientific issue given that such data give insights into the spatial differences of global temperature change and can assist in combating climate change. Based on the reanalysis of seven widely accepted datasets, which include trends in climate change and spatial interpolation of the land air temperature data, the changes in the temperature of major countries from 1981 to 2019 and the spatial-temporal characteristics of global temperature change have been assessed. The results revealed that the global land air temperature from the 1980 s to 2019 varied at a rate of 0.320℃/10 a, and exhibited a significantly increasing trend, with a cumulative increase of 0.835℃. The mean annual land air temperature in the northern and southern hemispheres varied at rates of 0.362℃/10 a and 0.147℃/10 a, respectively, displaying significantly increasing trends with cumulative increases of 0.828℃ and 0.874℃, respectively. Across the globe, the rates of change of the mean annual temperature were higher at high latitudes than at middle and low latitudes, with the highest rates of change occurring in regions at latitudes of 80°–90°N, followed by regions from 70°–80°N, then from 60°–70°N. The global land surface air temperature displayed an increasing trend, with more than 80% of the land surface showing a significant increase. Greenland, Ukraine, and Russia had the highest rates of increase in the mean annual temperature;in particular, Greenland experienced a rate of 0.654℃/10 a. The regions with the lowest rates of increase of mean annual temperature were mainly in New Zealand and the equatorial regions of South America, Southeast Asia, and Southern Africa, where the rates were <0.15℃/10 a. Overall, 136 countries(93%), out of the 146 countries surveyed, exhibited a significant warming, while 10 countries(6.849%) exhibited no significant change in temperature, of which 3 exhibited a downward trend. Since the 1980 s, there have been 4, 34 and 68 countries with levels of global warming above 2.0℃, 1.5℃ and 1.0℃, respectively, accounting statistically for 2.740%, 23.288% and 46.575% of the countries examined. This paper takes the view that there was no global warming hiatus over the period 1998–2019.     

中国城市扩展对气温观测的影响及其高估程度(英文)

Since the implementation of the reform and opening up policy in China in the late 1970s, some meteorological stations ’entered’ cities passively due to urban expansion. Changes in the surface and built environment around the stations have influenced observations of air temperature. When the observational data from urban stations are applied in the interpolation of national or regional scale air temperature dataset, they could lead to overestimation of regional air temperature and inaccurate assessment of warming. In this study, the underlying surface surrounding 756 meteorological stations across China was identified based on remote sensing images over a number of time intervals to distinguish the rural stations that ’entered’ into cities. Then, after removing the observational data from these stations which have been influenced by urban expansion, a dataset of background air temperatures was generated by interpolating the observational data from the remaining rural stations. The mean urban heat island effect intensity since 1970 was estimated by comparing the original observational records from urban stations with the background air temperature interpolated. The result shows that urban heat island effect does occur due to urban expansion, with a higher intensity in winter than in other seasons. Then the overestimation of regional air temperature is evaluated by comparing the two kinds of grid datasets of air temperature which are respectively interpolated by all stations’ and rural stations’ observational data. Spatially, the overestimation is relatively higher in eastern China than in the central part of China; however, both areas exhibit a much higher effect than is observed in western China. We concluded that in the last 40 years the mean temperature in China increased by about 1.58℃, of which about 0.01℃ was attributed to urban expansion, with a contribution of up to 0.09℃ in the core areas from the overestimation of air temperature.     

Variations of the temperature and solar activity in China

In this paper we analyze daily mean, minimum, and maximum temperature data collected at 119 meteorological stations over five regions of China during the period 1951-2010. The series of minimum, maximum, and mean temperatures from each climatic region have similar signatures, but there are differences among the five regions and the countrywide average. The results indicate that the periods of faster warming were not synchronous across the regions studied： warming in northeast China and Tibet began in 1986, while in central-east, southeast, and northwest China the warming emerged in 1995. Furthermore, central-east and northwest China, and Tibet, have warmed continuously since 2000, but the temperature has decreased during this period in southeast China. We evaluated the evolution of these temperature series using a novel nonlinear filtering technique based on the concept of the lifetime of temperature curves. The decadal to secular evolution of solar activity and temperature variation had similar signatures in the northeast, southeast, and northwest re- gions and the average across the whole country, indicating that solar activity is a significant control on climate change over secular time scales in these regions. In comparison with these regions, the signatures were different in central-east China and Tibet because of regional differences （e.g., landforms and elevation） and indirect effects （e.g., cloud cover influencing the radiation balance, thereby inducing climate change）. Furthermore, the results of wavelet analysis indicated that the El Nino Southem Oscillation （ENSO） has had a significant impact on climate change, but at different times among the regions, and these changes were most probably induced by differing responses of the atmospheric system to solar forcing.     

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.     

Radiative forcing over China due to albedo change caused by land cover change during 1990–2010

Land cover change affects surface radiation budget and energy balance by chang- ing 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 WIm2, 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.     

1910-2014年湖南省均一化气温序列构建及其变化特征（英文）

Based on the statistical method and the historical evolution of meteorological stations,the temperature time series for each station in Hunan Province during 1910–2014 are tested for their homogeneity and then corrected.The missing data caused by war and other reasons at the 8 meteorological stations which had records before 1950 is filled by interpolation using adjacent observations,and complete temperature time series since the establishment of stations are constructed.After that,according to the representative analysis of each station in different time periods,the temperature series of Hunan Province during 1910–2014 are built and their changes are analyzed.The results indicate that the annual mean temperature has a significant warming trend during 1910–2014 and the seasonal mean temperature has the largest rising amplitude in winter and spring,followed by autumn,but no significant change in summer.Temperature variation over Hunan Province has several significant warm-cold alternations and more frequent than that in whole China.Annual and seasonal mean temperatures except summer and autumn have abrupt warming changes in the recent 100 years.The wavelet analysis suggests that the annual and four seasonal mean temperatures in recent 100 years have experienced two climatic shifts from cold to warm.     

长江三角洲城市带扩展对区域温度变化的影响

利用DMSP/OLS 夜间灯光数据、土地利用统计数据和气象站常规观测资料, 结合NOAA/AVHRR、MODIS 反演的月地表温度数据, 定量考察了长江三角洲城市群热岛增温效应对区域温度气候趋势的贡献, 结果表明: ① 1992-2003 年长江三角洲城市化经历了一个快速的空间扩展过程, 宁镇扬、苏锡常、上海大城市区、杭州湾4 个城市群构成了一个“之” 字形城市带, 城市群之间出现城市化连片趋势, 城市带区域内1961-2005 年年平均气温增温 速率为0.28~0.44 ^oC/10a, 显著高于非城市带区域。② 城市热岛效应对区域平均温度的影响以夏秋季最强, 春季次之, 冬季最弱。③ 长江三角洲城市带热岛强度和城市总人口对数呈线性正相关关系。④ 城市带增温效应使得区域的年平均气温在1961-2005 年间增加了0.072 ^oC, 其中1991-2005 年间增温幅度为0.047 ^oC; 年最高气温升高了0.162 ^oC, 其中1991-2005 年间 增温幅度为0.083 ^oC, 表明1991-2005 年间长江三角洲城市带的空间扩展正在改变区域温度变化趋势, 且这种增温趋势显著。     

中国西北近50 a来气温变化特征的进一步研究

 利用国家气象信息中心最新整编的西北地区135站1960—2005年逐月资料,通过对该地区温度变化特征的分析,在前人研究成果的基础上,进一步揭示出了近50 a来西北地区气温变化的一些新特征: ①西北地区的年和各季节均表现为一致的增温趋势,但陕西南部在夏季出现降温的趋势。冬季和秋季,从塔里木盆地西侧到河套地区,在35°—40°N的带状区域内是增温趋势最强的区域。西北区域整体年平均气温的变化幅度达0.37℃/10a,冬季增温可达0.56℃/10a。无论是年或四季平均的增温率,西北地区都比全国平均的要高。②西北地区冬季和年的平均气温在20世纪80年代中期以后开始表现为明显上升趋势;但春季、夏季和秋季均到了20世纪90年代中期以后,才开始出现气温明显上升的趋势。③西北地区年气温异常首先表现为全区一致的变化型,然后依次为南北相反变化型和陕南气温变化与其他地区不同的独特性。且整体一致型变化近50 a来呈加强态势,而陕南与西北其他地区气温非同步变化的趋势在逐渐缩小。④西北地区近50 a来年气温可分为南疆-高原区、北疆区、西北东部区3个主要空间异常气候区。且从长期倾向来看,南疆-高原区和北疆区有明显的上升变化倾向,西北东部区则表现为波动式的上升趋势。     

中国城市扩展对气温观测的影响及其高估程度

由于中国城市扩展导致部分气象站点被动进入城市内部,从而造成对区域气温的高估.本文利用遥感多期影像对中国700多个气象站点各历史时期的下垫面进行判别,得到"进城"站点及其进城时间.通过比较"进城"站点的观测数据和背景气温,计算出70年代以来"进城"气象站点上的平均热岛效应强度,并对热岛效应强度的季节性筹异进行了分析,得出70年代以来秋冬季节的热岛强度高于春季和夏季的结沦.通过比较真实气温和背景气温的空间数据,识别出了气温高估区域,得出中国东部地区的气温高估略高于中部地区,东部地区和中部地区的气温高估均远高于西部地区的结论.通过计算真实气温和背景气温序列的年平均气温变化趋势,得出近40年来全国的增温值约为1.58℃,其中凶城市扩展带来的增温贡献约为0.01℃,在气温高估的核心区域的贡献约为0.09℃.     

20世纪末中国中东部耕地扩张对表面气温影响的模拟

利用WRF模式,通过4个21年（1980-2000年）的模拟实验,研究了20世纪末中国中东部耕地扩张对表面气温的影响。控制实验分析发现WRF模式能够捕捉温度场的空间格局,模拟与观测的季节平均温度场的相关系数为0.91~0.99（P < 0.001）,但模拟温度比观测温度系统性偏低2~3 ℃。控制实验与敏感实验对比分析发现,东北区和中部区的毁林和毁草开荒具有降温效应,冬季平均降幅约为-0.41 ℃,居四季之首,主要是由地表反照率增加,净短波辐射减少,感热通量随之减少所致;东南区的毁林开荒具有升温效应,夏季温度升幅最大,平均升幅为0.14 ℃,主要原因是地表粗糙度减小,湍流减弱,热量在近地层集聚,难以扩散。农业扩张的升、降温效应主要出现在局地,对区域温度变化的影响甚微,一方面是因为农业扩张占区域面积份数甚小,另一方面是因为升、降温效应在区域平均过程中相互抵消。     

中国南方不同土地利用/覆被类型对气温升温的影响

基于我国南方六省国家气象台站历史气象资料、1:10万土地利用/覆被数据和NCEP再分析气温资料,通过比较气温变化在不同观测环境气象站之间的差异,分析中国南方三种主要土地利用/覆被类型对气温趋势的影响。结果显示:土地利用/覆被类型对气温趋势具有稳定的影响,建设用地的年均温、年均最高和最低气温的升温幅度均最高,耕地次之,林地最小。进一步利用再分析资料剔除区域大尺度气候背景影响后,建设用地的年均温升温趋势仍最大(0.105℃/10a),其次是耕地(0.056℃/10a),林地的升温趋势最小(-0.025℃/10a),且为负。这表明对于研究区气温的升温趋势,林地具有抑制作用,建设用地具有增强作用,且增强作用较耕地强。林地的各季节平均气温的变化幅度同样低于非林地。     

西安城市化对气温变化趋势的影响

利用1951-2006年西安及周围3站点的气象数据分析了城市气温变化和周围台站温度变化的差异,给出了4个测站不同阶段、不同季节城市化影响气温变化的趋势系数及线性变化趋势。结果表明：城市化对气温的影响具有明显的阶段性和季节性。1980年以前,无论平均气温还是月最低气温和最高气温,西安与其周围站点的线性趋势系数及线性变化趋势相差不大;但在1980年以后,城市站的线性趋势系数明显大于周围站点的趋势系数,特别是在1993年以后,西安站的平均气温、最高和最低气温线性趋势系数远大于其周围站点的趋势系数,是周围站点的1.6~3.5倍,说明城市的热岛效应不但提高了城市的温度同时也改变城市的增温率,使得城市气温增温率加大。西安及其周围站的线性增暖趋势在春季最大,其中西安达到2.20 ^oC/10a,是其它季节的2~4倍;秋季的线性增暖幅度次之,夏季最小。热岛效应对最高气温的最大贡献在春季,对最低气温的最大贡献在冬季。     

长江三角洲气温变化特征及城市化影响

基于长江三角洲国家基本/基准站历史气象资料和区域人口资料,分析了1959~2005年和1981~2005年期间长江三角洲气温的年和季节变化特征,气温变化在大城市、中等城市和小城镇站之间的差异,以及城市化效应对气温的增温率和增温贡献率。结果表明,过去47年和25年期间,长江三角洲年均气温、年均最高和最低气温都显著增加,增温率都是冬季和春季较高,夏季最低。大城市站增温率明显高于小城镇和中等城市站,城市化效应对大城市气温基本上都是增温作用,其中对平均最低气温的增温率及贡献率最大,对平均最高气温都最小。长江三角洲气温变化趋势和增温率、城市化效应的增温率及增温贡献率与其他地区具有较好的一致性。