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1.
Characterization and estimation of urban heat island at Toronto: impact of the choice of rural sites 总被引：3，自引：2，他引：1
In this study, the urban heat island of Toronto was characterized and estimated in order to examine the impact of the selection of rural sites on the estimation of urban heat island (UHI) intensity (?T u-r). Three rural stations, King Smoke Tree (KST), Albion Hill, and Millgrove, were used for the analysis of UHI intensity for two urban stations, Toronto downtown (Toronto) and Toronto Pearson (Pearson) using data from 1970 to 2000. The UHI intensity was characterized as winter dominating and summer dominating, depending on the choice of the rural station. The analyses of annual and seasonal trends of ?T u-r suggested that urban heat island clearly appears in winter at both Toronto and Pearson. However, due to the mitigating effect on temperature from Lake Ontario, the estimated trend of UHI intensity was found to be less at Toronto compared to that at Pearson which has no direct lake effect. In terms of the impacts of the rural stations, for both KST and Millgrove, the trends in UHI intensity were found to be statistically significant and also were in good agreement with the estimates of UHI intensities reported for other large cities in the USA. Depending on the choice of the rural station, the estimated trend for the UHI intensity at Toronto ranges from 0.01°C/decade to 0.02°C/decade, and that at Pearson ranges from 0.03°C/decade to 0.035°C/decade during 1970–2000. From the analysis of the seasonal distribution of ?T u-r, the UHI intensity was found to be higher at Toronto in winter than that at Pearson for all three rural stations. This was likely accounted for by the lower amount of anthropogenic heat flux at Pearson. Considering the results from the statistical analysis with respect to the geographic and surface features for each rural station, KST was suggested to be a better choice to estimate UHI intensity at Toronto compared to the other rural stations. The analysis from the current study suggests that the selection of a unique urban–rural pair to estimate UHI intensity for a city like Toronto is a critical task, as it will be for any city, and it is imperative to consider some key features such as the physiography, surface characteristics of the urban and rural stations, the climatology such as the trends in annual and seasonal variation of UHI with respect to the physical characteristics of the stations, and also more importantly the objectives of a particular study in the context of UHI effect. 相似文献
2.
This paper describes the statistical characteristics and temporal variability of the urban heat island (UHI) intensity in Buenos Aires using 32-year surface meteorological data with 1-h time intervals. Seasonal analyses show that the UHI intensity is strongest during summer months and an “inverse” effect is found frequently during the afternoon hours of the same season. During winter, the UHI effect is in the minimal. The interannual trend and the seasonal variation of the UHI for the main synoptic hours for a longer record of 48?years are studied and associated to changes in meteorological factors as low-level circulation and cloud amount. Despite the population growth, it was found a negative trend in the nocturnal UHI intensity that could be explained by a decline of near clear-sky conditions, a negative trend in the calm frequencies and an increase in wind speed. Urban to rural temperature differences and rural temperatures are negatively correlated for diurnal and nocturnal hours both for annual and seasonal scales. This result is due to the lower interannual variability of urban temperatures in comparison to rural ones. 相似文献
3.
利用阳泉市3个国家级气象站资料分析了阳泉市城市热岛效应的年际变化、季节变化、月变化和日变化特征,结果表明：阳泉市存在弱的城市热岛效应,1972年-2011年平均热岛强度0．554℃。阳泉市热岛强度冬、秋季强,春、夏季弱;12月最强,5月最弱;阳泉市热岛强度整体呈显著上升趋势,热岛强度的增加主要是由于夏季热岛强度的增强。热岛强度日变化表现为12时最小,从傍晚开始随降温逐渐增大,到早晨气温降到最低时最大,日出之后迅速减小;2008年-2011年最强热岛强度出现在2010年1月14日08时达7．9℃。阳泉市主要城市发展因子与霾日数、气温呈显著正相关,在目前的经济发展水平条件下,城市化发展可能使阳泉城市温度增高,城市绿地面积的增加可能对热岛效应有缓解。 相似文献
4.
5.
利用1972－2011年阳泉市3个国家级气象站资料、2011年36个乡镇区域自动站气温资料,分析了阳泉市城市热岛效应的年际变化、季节变化、月变化和日变化特征。结果表明：阳泉市存在弱的城市热岛效应,1972－2011年平均热岛强度0.554 ℃。阳泉市城市热岛强度整体呈显著上升趋势,热岛强度的增加主要是由于夏季热岛强度的增强;热岛强度冬、秋季强,春、夏季弱;12月最强,5月最弱;热岛强度日变化表现为12时最小,从傍晚开始随降温逐渐增大,到早晨气温降到最低时最大,日出之后迅速减小;2008－2011年最强热岛强度出现在2010年1月14日08时,达7.9 ℃。阳泉在升温天气热岛强度变幅增大,易在早晨形成较强城市热岛,下午形成城市冷岛;降温天气热岛强度变幅减小;温度变化较小时则易维持弱的城市热岛。阳泉市主要城市发展因子与霾日数、气温呈显著正相关,在目前的经济发展水平条件下,阳泉市城市化发展可能使城市温度增高,城市绿地面积的增加可能对热岛效应有缓解作用。 相似文献
6.
利用1988—2006年20景LandsatTM和ETM＋数据分析了北京市城市热岛的季节变化特征。通过反演地表温度,建立统一的城市和农村区域,计算了城市热岛强度,并采用多项式拟合获取了城市热岛强度的季节变化曲线;同时,分析了热岛强度季节特征与气候因子的关系。另外利用4景2005—2006年不同季节Landsat TM影像,分析了不同季节城市热岛的空间变化特征,并选择穿越北京城区的两条不同方向剖线（SE-NW和SW-NE）,分析了沿剖线方向城市热岛与地表类型的关系。结果显示,北京城市热岛具有明显的季节变化特征,与总云量的季节变化关系显著。最大热岛强度出现在夏季,呈现片状发散和零星热岛并存的空间分布特征。冬季为冷岛特征,其空间分布与夏季热岛一致。春秋两季热岛强度最小,但春季热岛空间差异较大。在相同季节,城市热岛强度和空间尺度在不同剖线方向具有明显的差异,这与不同地类的空间分布有关。 相似文献
7.
Statistical and dynamical characteristics of the urban heat island intensity in Seoul 总被引：2，自引：0，他引：2
The statistical and dynamical characteristics of the urban heat island (UHI) intensity in Seoul are investigated for non-precipitation days and precipitation days using 4-year surface meteorological data with 1-h time intervals. Furthermore, the quantitative influence of synoptic pressure pattern on the UHI intensity is examined using a synoptic condition clustering method. The statistical analysis shows that the daily maximum UHI intensity in Seoul for non-precipitation days is strongest in autumn (4.8°C) and weakest in summer (3.5°C). The daily maximum UHI intensity is observed around midnight in all seasons except in winter when the maximum occurrence frequency is found around 08 LST. This implies that anthropogenic heating contributes to the UHI in the cold season. The occurrence frequency of the UHI intensity has a negatively skewed distribution for non-precipitation days but a positively skewed distribution for precipitation days. The amplitude of the heating/cooling rate and the difference in the heating/cooling rate between the urban and rural areas are smaller in all seasons for precipitation days than for non-precipitation days, resulting in weaker UHI intensities for precipitation days. The urban cool island occurs very often in the daytime, with an occurrence frequency being 77% of the total non-precipitation days in spring. The analysis of the impact of large-scale dynamical forcing shows that the daily maximum UHI intensity varies with synoptic pressure pattern, ranging from ?22% in spring to 28% in summer relative to the seasonal mean daily maximum UHI intensity. Comparison of the UHI intensity calculated using station-averaged temperatures to that based on the conventional two-station approach indicates that local effects on the UHI intensity are minimized by using multiple-station data. Accordingly, an estimation of the UHI intensity using station-averaged temperatures for both urban and rural areas is suggested. 相似文献
8.
Based on an in-homogeneity adjusted dataset of the monthly mean temperature, minimum and maximum temperature, this paper analyzes the temporal characteristics of Urban Heat Island (UHI) intensity at Wuhan Station, and its impact on the long-term trend of surface air temperature change recorded during 1961–2015 by using an urban-rural method. Results show that UHI effect is obvious near Wuhan Station in the past 55 years, especially for minimum temperature. The strongest UHI intensity occurs in summer and the weakest in winter. For the period 1961–2004, UHI intensity undergoes a significant increase near the urban station, with the increase especially large for the period 1988–2004, but the last 10 years witness a significant decrease, with the decrease in minimum temperature being more significant than that of maximum temperature. The annual mean urban warming and its contribution to overall warming are 0.18?C/10yr and 48.8% respectively for the period 1961–2015, with a more significant and larger urbanization effect seen in Tmin than Tmax. Thus, a large proportion warming, about half of the overall increase in annual mean temperature, as observed at the urban station, can be attributed to the rapid urbanization in the past half a century. 相似文献
9.
Manju Mohan Yukihiro Kikegawa B. R. Gurjar Shweta Bhati Narendra Reddy Kolli 《Theoretical and Applied Climatology》2013,112(3-4):647-658
Urban heat island intensities (UHI) have been assessed based on in situ measurements and satellite-derived observations for the megacity Delhi during a selected period in March 2010. A network of micrometeorological observational stations was set up across the city. Site selection for stations was based on dominant land use–land cover (LULC) classification. Observed UHI intensities could be classified into high, medium and low categories which overall correlated well with the LULC categories viz. dense built-up, medium dense built-up and green/open areas, respectively. Dense urban areas and highly commercial areas were observed to have highest UHI with maximum hourly magnitude peaking up to 10.7 °C and average daily maximum UHI reaching 8.3 °C. UHI obtained in the study was also compared with satellite-derived land surface temperatures (LST). UHI based on in situ ambient temperatures and satellite-derived land surface temperatures show reasonable comparison during nighttime in terms of UHI magnitude and hotspots. However, the relation was found to be poor during daytime. Further, MODIS-derived LSTs showed overestimation during daytime and underestimation during nighttime when compared with in situ skin temperature measurements. Impact of LULC was also reflected in the difference between ambient temperature and skin temperature at the observation stations as built-up canopies reported largest gradient between air and skin temperature. Also, a comparison of intra-city spatial temperature variations based UHI vis-à-vis a reference rural site temperature-based UHI indicated that UHI can be computed with respect to the station measuring lowest temperature within the urban area in the absence of a reference station in the rural area close to the study area. Comparison with maximum and average UHI of other cities of the world revealed that UHI in Delhi is comparable to other major cities of the world such as London, Tokyo and Beijing and calls for mitigation action plans. 相似文献
10.
利用建站以来鞍山站和海城乡村站的一日四次观测数据和逐日平均、最低和最高气温资料,对1951-2017年鞍山市年、四季和各月平均气温和极端气温变化特征及其变率进行了分析,并对鞍山城市热岛变化进行探讨。结果表明：1951-2017年鞍山市年平均最低气温的递增趋势最强、平均气温次之、平均最高气温最弱,且均通过显著性检验。1951-2017年鞍山市年极端最高气温变化呈弱递减趋势,1951-1987年（突变前）呈递减趋势、1988-2017年（突变后）为递增趋势。1951-2017年鞍山市年极端最低气温呈显著递增趋势,1951-1987年（突变前）较整个阶段递增趋势更强,1988-2017年（突变后）呈递减趋势;突变前后极端最高和极端最低气温呈反相变化特征。1958-2017年鞍山市年最低气温的城市热岛强度最大、平均气温次之,最高气温最小、递增趋势最弱;秋、冬季鞍山城市热岛强度较其他季节更强,热岛指数递增显著;在每日4次定时气温观测中,14时鞍山市热岛强度最小,热岛指数呈递减趋势,其余时次均呈显著递增趋势,其中,02时鞍山热岛强度最强;鞍山市平均气温变化呈显著增暖趋势,城市热岛强度和热岛指数均呈显著递增,夜间递增尤为突出,说明鞍山城市热岛的显著增强是鞍山市气候变暖的一个主要原因。 相似文献
11.
1978—2008年城市化对北京地区气温变化影响的初步分析 总被引：2，自引：2，他引：0
应用北京地区20个常规站1978-2008年经均一性序列多元分析方法均一化处理的气温数据,初步分析了北京地区城市化对年平均和不同季节日最高、最低以及平均气温的影响。结果表明,1978—2008年,年平均日最低、平均气温空间分布自北向南、自西向东,温度逐渐升高,在城区达到最高,日最高气温表现为从西向东南逐步升高,在城区形成较为明显的热岛。温度变化趋势表明,各站日最低气温、平均气温、最高气温均呈升温趋势。城市化对北京地区城区及近郊区站点日平均气温和最低气温影响最大,对自北部佛爷顶至昌平到城区一带站点的最高气温影响最大。城市化对北京(观象台)站的增温影响最为明显,对城区站点温度平均的增温影响次之,对全市站点温度平均的增温影响最小。城市化对观象台站、城区站点平均、全市站点平均日平均气温、最低气温的年平均、各季节均非常显著,其中在秋季影响最大,对日最高气温的影响则是在夏季最大。 相似文献
12.
北京"城市热岛"效应现状及特征 总被引：37，自引：16，他引：21
利用2002年北京自动气象站资料,对北京“城市热岛”效应现状进行了分析。为了与20世纪70年代的结果相比较,选择城区代表站为天安门广场站,城郊代表站为朝阳气象站站。与20世纪70年代相比,目前北京的“城市热岛”表现出一些新特点:1)利用城区与城郊日均温差表示的“城市热岛”强度的统计结果表明,现在北京的“城市热岛”效应在夏季最强,秋、冬季次之,春季最弱,2)除夏季“城市热岛”整天存在(午后的平均强度在2℃左右)以外,其他季节的午后,天安门广场地区经常出现“城市冷岛”现象。3)北京“城市热岛”消失的极限风速没有发生系统性变化,当风速>3级时,北京“城市热岛”基本上消失。作者还研究了北京“城市热岛”形成和消失的日变化特征,以及“城市热岛”强度对风速等气象要素变化的响应特征。值得指出的是,对强“城市热岛”的个案分析显示,冬季夜晚“城市热岛”强度经常表现出较大的波动性,与此相伴随,城郊地面风出现风向突变和风速的阵性现象。 相似文献
13.
The climatology and long term trends of sunshine duration (SSD), total cloud amount (TCC) and surface temperature are studied based on surface observations at 84 stations across China from 1961 to 2009. These stations were classified into metropolis, large city, small city and rural station based on their populations and specific station locations. Difference in SSD and its implication for surface temperature among four station categories are analyzed. Different SSD decreasing rates among four station categories were found. The maximum decreasing rate occurred at metropolis stations (-89.2 h per decade) and the minimum rate occurred at rural station (-54.1 h per decade). TCC also showed a negative trend. The correlation coefficients between decadal variability of SSD and TCC were significantly positive, which implied that the dimming during this period was apparently not explained by TCC. Among all station categories, the maximum temperatures (Tmax) showed a similar positive trend, however, the minimum temperatures (Tmin) increased much faster at urban stations than at rural stations. This suggested that the faster decline of SSD at urban stations could partly dampen the effect of urban heat island on Tmax. 相似文献
14.
利用北京地区城郊16个气象观测站1979～2008年逐日平均、最高和最低温度的均一化资料,分析了近30年北京地区城、郊区极端温度事件发生频次(强度)的变化趋势,并对比了城郊差异以及城市热岛强度对城郊差异的影响.研究结果显示:从发生频次来看,近30年城区极端低温事件的减小幅度[5.94 d (10 a)-1]高于郊区的减小幅度[-5.28 d (10 a)-1],而极端高温事件的增加幅度在城区[4.33 d (10 a)-1]和郊区[4.42 d (10 a)-1]之间差别不大,定量化的诊断结果进一步证明了城区和郊区在极端温度事件发生频次上的差别很小.从发生强度来看,近30年城区极端温度事件的年平均发生强度明显高于郊区,但在变化趋势上,城区极端低温事件的减弱幅度略高于极端高温事件的增强幅度,相差0.042℃(10 a)-1,而在郊区极端低温事件的减弱幅度却略低于极端高温事件的增强幅度,相差0.052℃(10 a)-1.城郊差异的定量化分析结果表明,极端温度事件在城区强度一般大于郊区强度,城区与郊区强度差值均为正值(除1982年和1985年极端高温事件强度差值为负).热岛强度与极端温度事件城郊差异的相关性统计发现,极端温度事件发生频次和发生强度在城郊之间的差别与热岛强度均没有明显的相关特征,该结果说明城市热岛效应对北京超大城市市区和郊区影响基本一致,其差异性是有限的. 相似文献
15.
根据1961—2012年陕西省均一化气温数据分析了秦岭南北两侧平均气温、最高气温、最低气温的年、季节变化特征,结果表明:秦岭南北两侧年平均气温、最高气温和最低气温均呈增加趋势,增加幅度南北分布不均,北麓温度增幅较南麓显著;气温季节变化存在一定差异,平均气温在春季和冬季增温显著,最高气温在春季增温显著,最低气温在冬季增温显著,秦岭南北两侧春季、秋季气温日较差变大,冬季和夏季气温日较差变小。为了进一步明确气温变化的原因,结合DMSP (defense mete-orological satellite program)/OLS (operational lines-can system) 数据将秦岭南北两侧分为5个区域,分别计算每个区域内城市化对气温变化的影响以及城市化影响的贡献率表明:秦岭北麓城市化过程较秦岭南麓快,城市化发展的差异,导致了城市化对秦岭南北两侧温度影响的不均匀性,秦岭北麓气温变化受城市化影响程度明显高于秦岭南麓,影响主要以平均气温和最低气温为主,城市化发展的差异加剧了秦岭南北两侧气温变化的非均匀性。 相似文献
16.
石家庄城市与郊县站地面平均最低、最高气温差异 总被引：3，自引：0，他引：3
应用石家庄地区17个站1955—2006年逐日最低、最高气温资料,统计分析了16个郊县站与石家庄市区站最低、最高气温的差值。结果表明:各郊县站年平均最低、最高气温均比石家庄市站低,最低气温偏低0.17～2.07℃,16个站平均偏低1.02℃;最高气温偏低0.01～0.55℃,16个站平均偏低0.28℃。郊县站平均最低气温偏低程度在冬季更明显,1月平均达到1.69℃,夏季偏低程度比较弱,但最弱的7月也有0.49℃;最高气温的偏低程度也在冬季明显,但季节性差异没有最低气温大。不论最低气温,还是最高气温,各县(市)站与石家庄市区站之间的差异均存在明显的随时间增大现象,最低气温20世纪90年代初以来增大尤其明显。石家庄市区站地面最低、最高气温记录反映出明显的城市热岛效应影响。 相似文献
17.
With the surface air temperature (SAT) data at 37 stations on Central Yunnan Plateau (CYP) for 1961–2010 and the Defense Meteorological Satellite Program/Operational Linescan System (DMSP/OLS) nighttime light data, the temporal-spatial patterns of the SAT trends are detected using Sen’s Nonparametric Estimator of Slope approach and MK test, and the impact of urbanization on surface warming is analyzed by comparing the differences between the air temperature change trends of urban stations and their corresponding rural stations. Results indicated that annual mean air temperature showed a significant warming trend, which is equivalent to a rate of 0.17 °C/decade during the past 50 years. Seasonal mean air temperature presents a rising trend, and the trend was more significant in winter (0.31 °C/decade) than in other seasons. Annual/seasonal mean air temperature tends to increase in most areas, and higher warming trend appeared in urban areas, notably in Kunming city. The regional mean air temperature series was significantly impacted by urban warming, and the urbanization-induced warming contributed to approximately 32.3–62.9 % of the total regional warming during the past 50 years. Meantime, the urbanization-induced warming trend in winter and spring was more significant than that in summer and autumn. Since 1985, the urban heat island (UHI) intensity has gradually increased. And the urban temperatures always rise faster than rural temperatures on the CYP. 相似文献
18.
利用2012~2013年北京中央商务区（Central Business District,CBD）加密观测资料,分析CBD区域城市热岛（Urban Heat Island,UHI）强度日变化和空间变化特征及其影响因子。研究发现,CBD区域气温高于周边自动站气温,平均偏高0.64℃;CBD区域城市热岛强度呈现夜间强、白天弱的现象,中午甚至存在“城市冷岛”现象。季节平均UHI日变化表现为:在夜间,秋季最强,冬季次之,春季和夏季较弱;在白天,夏季最强,冬季次之,春季和秋季较弱。相对于晴朗无风天气,雾、雨、大风等天气对城市热岛有抑制作用,并结合小波分析结果发现,秋季城市热岛强度强于冬季是由于冬季雾、雨、大风等天气过程发生比例较高的缘故。CBD区域城市热岛空间变化特征研究发现,花园、学校等绿地有助于缓解城市热岛效应。雾日、雨日和大风日的CBD区域城市热岛强度空间变化标准差比晴朗无风日小。 相似文献
19.
以高山站为背景研究城市化对气温变化趋势的影响 总被引：4，自引：0，他引：4
本文基于1957~2005年的逐日气象资料,对比分析了中国东部7组高山气象站和山下附近的城市气象站年 与四季气温变化趋势.在此基础上,利用高山站作为气候变化背景场来分析城市化对平均气温、最高气温、最低气温变化趋势影响的性质和程度,及其对气温变化非对称性的影响.结果表明:平均气温和最低气温变化趋势城市站多比高山站大,而最高气温变化趋势高山站多比城市站大;城市站最低气温变化趋势均大于最高气温变化趋势,具有明显的非对称性现象,而高山站这种表现十分微弱.城市站气温变化受到明显的城市化影响,对于平均气温和最低气温以正影响为主,而对于最高气温为负影响为主,说明城市化对气温变化的影响也存在非对称性.城市化影响的非对称性是气温变化非对称性形成的主要因素. 相似文献