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1.
Su-Jong Jeong Chang-Hoi Ho Kwang-Yul Kim Jinwon Kim Jee-Hoon Jeong Tae-Won Park 《Climatic change》2010,99(3-4):625-635
Inclusion of the effects of vegetation feedback in a global climate change simulation suggests that the vegetation–climate feedback works to alleviate partially the summer surface warming and the associated heat waves over Europe induced by the increase in atmospheric CO2 concentrations. The projected warming of 4°C over most of Europe with static vegetation has been reduced by 1°C as the dynamic vegetation feedback effects are included.. Examination of the simulated surface energy fluxes suggests that additional greening in the presence of vegetation feedback effects enhances evapotranspiration and precipitation, thereby limiting the warming, particularly in the daily maximum temperature. The greening also tends to reduce the frequency and duration of heat waves. Results in this study strongly suggest that the inclusion of vegetation feedback within climate models is a crucial factor for improving the projection of warm season temperatures and heat waves over Europe. 相似文献
2.
华北-华东地区高温热浪与土壤湿度的关系研究 总被引：2，自引：1，他引：1
利用观测站点的日最高气温、土壤湿度旬观测资料以及土壤湿度再分析资料等,分析了华北-华东地区高温热浪次数的时空变化特征及其与土壤湿度的关系。结果表明:1960s以及1990-2010年为高温热浪次数的高值期,1970s-1980s为低值期。利用旋转经验正交函数分解得到土壤湿度的3个气候分区,分区内前期(3-5月)和同期(6-7月)的土壤湿度与6、7月份高温热浪次数基本呈负相关关系,并且同期相关性更显著。在华北-华东北部与中部,5月下旬土壤湿度与6月高温热浪次数、6月上、中旬平均土壤湿度与6月高温热浪次数、7月平均土壤湿度与7月高温热浪次数的相关性均显著。 相似文献
3.
Daily output from the PRUDENCE ensemble of regional climate simulations for the end of the twentieth and twenty-first centuries over Europe is used to show that the increasing intensity of the most damaging summer heat waves over Central Europe is mostly due to higher base summer temperatures. In this context, base temperature is defined as the mean of the seasonal cycle component for those calendar days when regional heat waves occur and is close, albeit not identical, to the mean temperature for July–August. Although 36–47% of future Central Europe July and August days at the end of the twenty-first century are projected to be extreme according to the present day climatology, specific changes in deseasonalized heat wave anomalies are projected to be relatively small. Instead, changes in summer base temperatures appear much larger, clearly identifiable and of the same order of magnitude as changes in the whole magnitude of heat waves. Our results bear important consequences for the predictability of central European heat wave intensity under global warming conditions. 相似文献
4.
The association between heat waves and the urban heat island effect can increase the impact on environment and society inducing biophysical hazards. Heat stress and their associated public health problems are among the most frequent. This paper explores the heat waves impact on surface urban heat island and on the local economy loss during three heat periods in Cluj-Napoca city in the summer of 2015. The heat wave events were identified based on daily maximum temperature, and they were divided into three classes considering the intensity threshold: moderate heat waves (daily maximum temperature exceeding the 90th percentile), severe heat waves (daily maximum temperature over the 95th percentile), and extremely severe heat waves (daily maximum temperature exceeding the 98th percentile). The minimum length of an event was of minimum three consecutive days. The surface urban heat island was detected based on land surface temperature derived from Landsat 8 thermal infrared data, while the economic impact was estimated based on data on work force structure and work productivity in Cluj-Napoca derived from the data released by Eurostat, National Bank of Romania, and National Institute of Statistics. The results indicate that the intensity and spatial extension of surface urban heat island could be governed by the magnitude of the heat wave event, but due to the low number of satellite images available, we should consider this information only as preliminary results. Thermal infrared remote sensing has proven to be a very efficient method to study surface urban heat island, due to the fact that the synoptic conditions associated with heat wave events usually favor cloud free image. The resolution of the OLI_TIRS sensor provided good results for a mid-extension city, but the low revisiting time is still a drawback. The potential economic loss was calculated for the working days during heat waves and the estimated loss reached more than 2.5 mil. EUR for each heat wave day at city scale, cumulating more than 38 mil. EUR for the three cases considered. 相似文献
5.
Heat waves have attracted increasing attention in recent years due to their frequent occurrence. The present study investigates the heat wave intensity and duration in China using daily maximum temperature from 753 weather stations from 1960 to 2010. In addition, its relationships with soil moisture local forcing on the ten-day period and monthly scales in spring and summer are analyzed using soil moisture data from weather stations and ERA40 reanalysis data. And finally, a mechanistic analysis is carried out using CAM5.1 (Community Atmosphere Model, version 5.1) coupled with CLM2 (Community Land Model, version 2). It is found that the heat wave frequency and duration show a sandwich distribution across China, with high occurrence rates in Southeast China and Northwest China, where the maximum frequency and duration exceeded 2.1 times and 9 days per year, respectively. The increasing trends in both duration and intensity occurred to the north of 35°N. The relationships between heat wave frequency in northern China in July (having peak distribution) and soil moisture in the earlier stage (from March to June) and corresponding period (July) are further analyzed, revealing a strong negative correlation in March, June and July, and thus showing that soil moisture in spring and early summer could be an important contributor to heat waves in July via positive subtropical high anomalies. However, the time scales of influence were relatively short in the semi-humid and humid regions, and longer in the arid region. The contribution in the corresponding period took place via positive subtropical high anomalies and positive surface skin temperature and sensible heat flux anomalies. 相似文献
6.
P. M. Della-Marta J. Luterbacher H. von Weissenfluh E. Xoplaki M. Brunet H. Wanner 《Climate Dynamics》2007,29(2-3):251-275
We investigate the large-scale forcing and teleconnections between atmospheric circulation (sea level pressure, SLP), sea
surface temperatures (SSTs), precipitation and heat wave events over western Europe using a new dataset of 54 daily maximum
temperature time series. Forty four of these time series have been homogenised at the daily timescale to ensure that the presence
of inhomogeneities has been minimised. The daily data have been used to create a seasonal index of the number of heat waves.
Using canonical correlation analysis (CCA), heat waves over western Europe are shown to be related to anomalous high pressure
over Scandinavia and central western Europe. Other forcing factors such as Atlantic SSTs and European precipitation, the later
as a proxy for soil moisture, a known factor in strengthening land–atmosphere feedback processes, are also important. The
strength of the relationship between summer SLP anomalies and heat waves is improved (from 35%) to account for around 46%
of its variability when summer Atlantic and Mediterranean SSTs and summer European precipitation anomalies are included as
predictors. This indicates that these predictors are not completely collinear rather that they each have some contribution
to accounting for summer heat wave variability. However, the simplicity and scale of the statistical analysis masks this complex
interaction between variables. There is some useful predictive skill of summer heat waves using multiple lagged predictors.
A CCA using preceding winter North Atlantic SSTs and preceding January to May Mediterranean total precipitation results in
significant hindcast (1972–2003) Spearman rank correlation skill scores up to 0.55 with an average skill score over the domain
equal to 0.28 ± 0.28. In agreement with previous studies focused on mean summer temperature, there appears to be some predictability
of heat wave events on the decadal scale from the Atlantic Multidecadal Oscillation (AMO), although the long-term global mean
temperature is also well related to western European heat waves. Combining these results with the observed positive trends
in summer continental European SLP, North Atlantic SSTs and indications of a decline in European summer precipitation then
possibly these long-term changes are also related to increased heat wave occurrence and it is important that the physical
processes controlling these changes be more fully understood. 相似文献
7.
Modeling the relative roles of the foehn wind and urban expansion in the 2002 Beijing heat wave and possible mitigation by high reflective roofs 总被引：1，自引：0，他引：1
Rapid urbanization has intensified summer heat waves in recent decades in Beijing, China. In this study, effectiveness of applying high-reflectance roofs on mitigating the warming effects caused by urban expansion and foehn wind was simulated for a record-breaking heat wave occurred in Beijing during July 13–15, 2002. Simulation experiments were performed using the Weather Research and Forecast (WRF version 3.0) model coupled with an urban canopy model. The modeled diurnal air temperatures were compared well with station observations in the city and the wind convergence caused by urban heat island (UHI) effect could be simulated clearly. By increasing urban roof albedo, the simulated UHI effect was reduced due to decreased net radiation, and the simulated wind convergence in the urban area was weakened. Using WRF3.0 model, the warming effects caused by urban expansion and foehn wind were quantified separately, and were compared with the cooling effect due to the increased roof albedo. Results illustrated that the foehn warming effect under the northwesterly wind contributed greatly to this heat wave event in Beijing, while contribution from urban expansion accompanied by anthropogenic heating was secondary, and was mostly evident at night. Increasing roof albedo could reduce air temperature both in the day and at night, and could more than offset the urban expansion effect. The combined warming caused by the urban expansion and the foehn wind could be potentially offset with high-reflectance roofs by 58.8 % or cooled by 1.4 °C in the early afternoon on July 14, 2002, the hottest day during the heat wave. 相似文献
8.
9.
The heat exchange between ocean and atmosphere over cold water is studied by calculating all terms in the energy balance twice each day for the year 1971 for the Sable Island region. The atmospheric long‐wave radiation is relatively constant because of frequent overcast and low clouds. The surface long‐wave balance is markedly negative in winter but slightly positive for a short time in summer, due to strong advection of warm moist air over the cold water. In winter, the turbulent fluxes are directed upwards and are strong, the upward fluxes beginning after the middle of August and lasting until mid‐March. The maximum daily values of latent heat flux are 400 to 500 ly day?1 (194 to 242 W m?2), about a third or a quarter of the magnitude over the warmer Gulf Stream water. The summer fluxes are fairly constant and directed downward. The water of the Labrador Current in the Sable Island region warms substantially from March to September and conversely cools intensely in the period November‐January. A comparison of the energy exchange for a current and for water without motion shows that the surface temperatures would be similar in summer, and the temperature drop would be about equal until November. From that time on, the surface temperature would level off for a water body with no current, but in actual conditions the surface temperature continues to drop to a late winter minimum of about 1°C. Atmospheric advection of latent heat was calculated by assuming that the daily precipitation was always caused first by condensation of all locally evaporated water with any remainder being supplied by water‐vapour advection. The main cause for atmospheric heating in the Sable Island area was found to be condensation of imported water vapour. The region is, in summer, a marked sink for atmospheric heat and water content. For water it remains a sink even in winter. For sensible heat it becomes a source from November to March. The warming of the atmosphere is caused by release of latent heat of advected water vapour in the period February‐August. During the months September‐January the heat sources are both water‐vapour advection and surface turbulent terms. 相似文献
10.
Ernest M. Agee 《Climatic change》1982,4(4):399-418
A diagnostic study of 80 yrs(1901–80) of surface temperatures collected at West Lafayette, Indiana, has been found to be in
tune with the global trend and that for the eastern two-thirds of the United States, namely, cold at the turn of the century,
warming up to about 1940, and then cooling to present. The study was divided into two cold periods (1901–18, 1947–80) and
a warm period (1919–46), based on the distribution of annual mean temperature. Decadal mean annual temperatures ranged from
10 °C in period I to 12.2 °C in period II, to 9.4 °C during the present cold period. Themean annual temperature for the 80 yr ranged from the coldest of 8.7 °C in 1979 to the warmest of 13.6 °C in 1939. Thedaily mean temperature for the entire 80-yr ranged from -4.7 °C on 31 January to 25.1 °C on 27 July. Thecoldest daily mean was -26.7 °C on 17 January, 1977, and thewarmest daily mean was 35 °C on 14 July, 1936. The range of values for thedaily mean maximum temperatures was -.2 °C on 31 January to 31.4 °C on 27 July. Corresponding values for thedaily mean minimum are -9.2 °C on 31 January and 18.7 °C on 27 July. The all-time extreme temperatures are -30.6 °C on 26 February, 1963 and
43.9 °C on 14 July, 1936.
Climatic variability has been considered by computing the standard deviations of a) the daily mean maximum and minimum temperature
per year, and b) the daily mean maximum and minimum temperatures for each day of the year for the 80-yr period. These results
have shown that there is more variability in the daily mean maximum per year than in the daily mean minimum, for each year
of the 80-yr period. Also the variability for both extremes has been greater in each of the two cold periods than in the warm
period. Particularly noticeable has been theincrease in the variability of the daily mean minima per year during the current cooling trend. Further, it has been determined that
the variability in the daily mean maxima and minima for each day of the year (based on the entire 80 yrs is a) two times greater
in the winter than in the summer for both extremes, and b) about the same for each in the summer, greater for daily maximum
in the spring and fall, but greater for the daily minimum during the winter. The latter result is undoubtedly related to the
effect of snow cover on daily minimum temperatures.
An examination of daily record maximum and minimum temperatures has been made to help establish climatic trends this century.
For the warm period, 175 record maxima and 68 record minima were set, compared to 213 record minima and 105 record maxima
during the recent cold period. For West Lafayette, the present climatic trend is definitely one of extreme record-breaking
cold. Evidence has also been presented to show the substantial increases in snowfall amounts in the lee regions of the Great
Lakes during the present cold period, due to the lake-induced snow squalls associated with cold air mass intrusions. The possible
impact of the cooling trend on agricultural activities has also been noted, due to a reduced growing season. 相似文献
11.
A study on the variability of atmospheric and oceanic processes over the Arabian Sea during contrasting monsoons 总被引：1，自引：0，他引：1
J. S. Chowdary C. Gnanaseelan S. K. Sinha B. Thompson 《Meteorology and Atmospheric Physics》2006,94(1-4):65-85
Summary The atmospheric and oceanic conditions associated with the southwest monsoon during the contrasting monsoon years of 2002
and 2003 over the Arabian Sea have been analyzed in the present study. Early onset of southwesterlies and reduced net heat
gain due to low solar radiation were responsible for low sea-surface temperatures (SSTs) over the Arabian Sea during 2002
pre-monsoon (particularly in May). Conversely, light winds and an increased net heat gain set up the pre-monsoon warming in
2003. The development and intensification of deep convection over a large area of the Arabian Sea prior to the onset of the
monsoon was observed during 2003, but was absent in 2002. Weak cross equatorial flow and a weak low level jet over the Arabian
Sea reduced moisture transport towards the Indian subcontinent in July 2002. This scenario helped to contribute to a prolonged
break in monsoon conditions during July. However, no such break in conditions occurred during July 2003. In 2002, the summer
monsoon cooling of the Arabian Sea occurred well before July, whereas in 2003 cooling occurred during July. Estimates of wind
driven Ekman (horizontal) and vertical transports showed maximum values in the month of June (July) in 2002 (2003). These
estimates clearly show the importance of horizontal and vertical advection in the summer cooling of the Arabian Sea.
During the southwest monsoon period, the Arabian Sea was warmer in 2003 than in 2002. Late onset of the southwesterlies in
June, late cooling of the Arabian Sea in July, and downwelling Rossby wave propagation were responsible for the warm SSTs
in 2003. Weak wind stress curl in July dampened the westward propagating sea surface height anomaly signals (Rossby waves)
before they reached the western Arabian Sea in 2002, whereas, in 2003 strong wind stress curl enhanced Rossby wave propagation.
During the summer monsoon period, subsurface temperatures in the south central Arabian Sea were warmer in 2003 than in 2002,
particularly in July and August. Strong Ekman convergence, solar penetration, and downwelling (downward velocities) are responsible
for the enhanced subsurface warming in 2003. 相似文献
12.
The results of two regional atmospheric model simulations are compared to assess the influence of the eastern tropical Atlantic sea-surface temperature maximum on local precipitation, transient easterly waves and the West African summer monsoon. Both model simulations were initialized with reanalysis 2 data (US National Center for Environmental Prediction and Department of Energy) on 15 May 2006 and extended through 6 October 2006, forced by synchronous reanalysis 2 lateral boundary conditions introduced four times daily. One simulation uses 2006 reanalysis 2 sea-surface temperatures, also updated four times daily, while the second simulation considers ocean forcing absent the sea-surface temperature maximum, achieved here by subtracting 3°K at every ocean grid point between 0° and 15°N during the entire simulation. The simulation with 2006 sea-surface temperature forcing produces a realistic distribution of June?CSeptember mean precipitation and realistic westward propagating swaths of maximum rainfall, based on validation against Tropical Rainfall Measuring Mission (TRMM) estimates. The simulation without the sea-surface temperature maximum produces only 57% of the control June?CSeptember total precipitation over the eastern tropical Atlantic and about 83% of the Sahel precipitation. The simulation with warmer ocean temperatures generates generally stronger circulation, which in turn enhances precipitation by increasing moisture convergence. Some local precipitation enhancement is also attributed to lower vertical thermal stability above the warm water. The study shows that the eastern tropical Atlantic sea-surface temperature maximum enhances the strength of transient easterly waves and broadens the spatial extent of associated precipitation. However, large-scale circulation and its interaction with the African continent, and not sea-surface temperatures, control the timing and trajectories of the waves. 相似文献
13.
Tošić Ivana Unkašević Miroslava Putniković Suzana 《Theoretical and Applied Climatology》2017,128(3-4):785-794
The extreme daily precipitation in Serbia was examined at 16 stations during the period 1961–2014. Two synoptic situations in May and September of 2014 were analysed, when extreme precipitation was recorded in western and eastern Serbia, respectively. The synoptic situation from 14 to 16 May 2014 remained nearly stationary over the western and central Serbia for the entire period. On 15 May 2014, the daily rainfall broke previous historical records in Belgrade (109.8 mm), Valjevo (108.2 mm) and Loznica (110 mm). Precipitation exceeded 200 mm in 72 h, producing the most catastrophic floods in the recent history of Serbia. In Negotin (eastern Serbia), daily precipitation of 161.3 mm was registered on 16 September 2014, which was the maximum value recorded during the period 1961–2014. The daily maximum in 2014 was registered at 6 out of 16 stations. The total annual precipitation for 2014 was the highest for the period 1961–2014 at almost all stations in Serbia. A non-significant positive trend was found for all precipitation indices: annual daily maximum precipitation, the total precipitation in consecutive 3 and 5 days, the total annual precipitation, and number of days with at least 10 and 20 mm of precipitation. The generalised extreme value distribution was fitted to the annual daily maximum precipitation. The estimated 100-year return levels were 123.4 and 147.4 mm for the annual daily maximum precipitation in Belgrade and Negotin, respectively.
相似文献14.
As global warming is scientifically and widely accepted, its impacts at regional scales are raising many questions for wine producers. In particular, climate parameters, especially temperature, play a decisive role in vine growth and grape ripening. An overview of expected climate change in terms of bioclimatic indexes (Winkler and Huglin) and thermal extremes in the wine-producing region of Champagne is presented. A variable-grid atmospheric general circulation model, ARPEGE-Climate, with a local zoom at 50 km over the area of interest, is used to investigate potential future changes in thermal extremes and bioclimatic indexes. Changes in daily maximum and minimum temperatures at key stages are discussed for three emission scenarios (B1, A1B, A2) that are currently used in studies of impacts of climate change. Model outputs are analyzed and critically assessed for a control period (1971–2000) and for changes in extreme events in relation to future scenarios, such as a decrease in extreme low temperatures in spring (April) during bud break and an increase in extreme high temperatures in summer, associated with more frequent heat waves during ripening. 相似文献
15.
2009年夏季中国高温分析 总被引：5，自引：3，他引：2
用常规气温资料及NCEP/NCAR再分析资料,对2009年夏季中国高温过程进行了研究。结果发现：（1）2009年中国中东部地区发生的高温日数相对历史同期偏多,集中在华北和长江以南地区。（2）大陆暖高压是导致6月华北黄淮一带高温过程的主要环流系统,7、8月副高的持续偏强和西伸是导致7、8月高温过程的主要环流系统。南亚高压与副热带高压有很好的响应关系,随着南亚高压的增强（减弱）东伸（西撤）,副高强度进而增强（减弱）西伸（东撤）,江南地区日最高温度分布范围也相应增大（缩小）。低层辐散、副热带西风急流轴偏北、急流中心偏西等有利于2009年夏季高温的发生和维持。（3）整层垂直积分大气加热场正异常可以作为高温的维持机制。 相似文献
16.
利用1998-2008年夏季（6-8月）武汉市居民逐日死亡人数（率）及同期逐日气象要素,分析极端高温对超额死亡率的影响程度及其阈值,采用逐步回归法建立定量评估模型,并进行预报效果检验和典型年回代检验,以利于开展高温对健康影响的评估及医疗气象预报。结果表明：武汉夏季人群超额死亡率可以定量表述;极端高温对超额死亡率影响最大,湿度、气压、风速几乎没有影响;超额死亡率随日最高气温升高呈指数规律增加,高温致超额死亡的阈值为35.0 ℃,“热日”比“非热日”平均死亡率高出50.7 %;采用日最高气温≥35 ℃的有效累积温度及当日平均气温建立的超额死亡率评估模型对2003年夏季一次高温热浪过程的回代试验、2007年和2008年夏季的评估试验效果较好,表明该模型可用于实际评估业务中。 相似文献
17.
利用98个测站逐日最高气温资料和ERA-interim再分析数据集,对1979~2018年西南地区夏季高温热浪的时空分布特征及其年际变化异常成因进行研究。结果表明:(1)气候平均西南地区夏季高温热浪频次从东南向西北减少,空间差异显著。近几十年来,西南地区高温热浪总体上显著增多,并表现出明显的年际和年代际变化特征。(2)EOF分解第1模态主要表现为全区一致型,可以反映西南地区夏季高温热浪变化的主要特征。第2模态空间分布大致呈现出南正北负的反相变化特征。(3)西南地区高温热浪偏多可能与对流层中层青藏高原以东至朝鲜半岛的明显高压异常相联系。在这个高压异常的控制下,西太平洋副热带高压向西移动,这有利于西南地区降水减少,云量减少,到达地表的太阳短波辐射增加。同时,东亚西风急流位置北移,可以阻止来自中高纬的冷空气入侵西南地区,引起这里降水减少干旱频发。最终,异常干燥和炎热的地表条件,与有利的大气环流背景相配合,从而造成西南地区夏季高温热浪事件的发生。 相似文献
18.
Raphael E. Okoola 《Meteorology and Atmospheric Physics》2000,73(3-4):177-187
Summary Climatological statistics of extreme temperature events over Kenya are established from the analysis of daily and monthly
maximum temperatures for a representative station (Nairobi Dagoretti Corner) over the period 1956–1997.
The months of June to August were shown to be the coldest with a mean monthly maximum temperature of less than 22 °C. Seasonal
(June to August) mean maximum temperature was 21.5 °C. Using this seasonal mean temperature for the period 1967–1997 delineated
1968 as the coldest year in this series and 1983 as the warmest year.
Spectral analysis of the seasonal data, for both the coldest and the warmest years, revealed that the major periods were the
quasi-biweekly (10 days) and the Intraseasonal Oscillations (23 days). Secondary peaks occurred at periods of 4–6 and 2.5–3.5
days.
A temperature threshold of 16.7 °C during July was used to define cold air outbreaks over Nairobi. This threshold temperature
of 16.7 °C was obtained from the mean July maximum temperature (20.9 °C) minus two standard deviations. Notable trends include
a decrease in the frequency of station-days, between 1956 and 1997, with temperatures less than 16.7 °C during July.
Surface pressure patterns indicate that the origin of the cold air is near latitude 25° S and to the east of mainland South
Africa. The cold air near 25° S is advected northwards ahead of the surface pressure ridge.
Received July 19, 1999 Revised January 11, 2000 相似文献
19.
With the goal of finding summer climate patterns in the region of Belgrade (Serbia) over the period 1888–2013, different techniques of multivariate statistical analysis were used in order to analyze the simultaneous changes of a number of climatologic parameters. An increasing trend of the mean daily minimum temperature was detected. In the recent decades (1960–2013), this increase was much more pronounced. The number of days with the daily minimum temperature greater or equal to 20 °C also increased significantly. Precipitation had no statistically significant trend. Spectral analysis showed a repetitive nature of the climatologic parameters which had periods that roughly can be classified into three groups, with the durations of the following: (1) 6 to 7 years, (2) 10 to 18 years, and (3) 21, 31, and 41 years. The temperature variables mainly had one period of repetitiveness of 5 to 7 years. Among other variables, the correlations of regional fluctuations of the temperature and precipitation and atmospheric circulation indices were analyzed. The North Atlantic oscillation index had the same periodicity as that of the precipitation, and it was not correlated to the temperature variables. Atlantic multidecadal oscillation index correlated well to the summer mean daily minimum and summer mean temperatures. The underlying structure of the data was analyzed by principal component analysis, which detected the following four easily interpreted dimensions: More sunshine-Higher temperature, Precipitation, Extreme heats, and Changeable summer. 相似文献
20.
北京不同区域表面气温的变化特征以及北京市观象台气温的代表性 总被引：2，自引：2，他引：0
利用北京地区14个观测站1990～2007年逐日和2004～2007年逐时的2 m气温观测资料,分析了北京城区、郊区、南部山区以及北部山区4个区域表面气温的年变化、季节变化以及春、夏、秋、冬4个季节的日变化特征,指出4个区域的气温变化特征具有明显的差异.在所有时间尺度上城区气温受城市热岛效应影响最大,表现为温度最高,郊区次之,南部山区较低,北部山区最低.1990～2007年4个区域的气温都表现出增温趋势,其中城区增温最明显,增温率明显大于其他区域.城区与其他区域气温的差异有明显的季节变化,城区与郊区、城区与北部山区气温的差异在冬季最大,夏季最小;城区与南部山区气温的差异在夏季最大,春季最小.在气温的日变化方面,城区气温在各个季节的日较差都是最小的,南部山区最大.通过比较作为北京代表站的北京市观象台的气温与4个区域的差异,发现观象台与城区气温在各个时间尺度上的差异都最小,与其他区域存在显著差异,北京市观象台气温主要代表了城区,对其他区域的代表性较差. 相似文献