共查询到20条相似文献，搜索用时 46 毫秒
1.
Edmilson D. Freitas Christopher M. Rozoff William R. Cotton Pedro L. Silva Dias 《Boundary-Layer Meteorology》2007,122(1):43-65
The Town Energy Budget (TEB) model, a detailed urban parameterisation using a generalised canyon geometry, coupled with the
Regional Atmospheric Modelling System (RAMS) is used to simulate the wintertime local circulation in the megacity environment
of the metropolitan area of Sao Paulo (MASP) in Brazil. Model simulations are performed using actual topography and land-use
fields. Comparison with a simple urban parameterisation based on the LEAF-2 scheme is also shown. Validation is based on comparison
between model simulations and observations. Sensitivity tests with TEB reveal an important interaction between the sea breeze
and the MASP heat island circulation. Even though topography is known to play an important role in the MASP region’s weather,
in these tests the simulations were performed without topography in order to unambiguously identify the interaction between
the two local circulations. The urban heat island (UHI) forms a strong convergence zone in the centre of the city and thereby
accelerates the sea-breeze front toward the centre of the city. The presence of the urban region increases the sea-breeze
front propagation mean speed by about 0.32 m s−1 when compared with the situation of no city. After its arrival in the urban region, the sea-breeze front stalls over the
centre of the city for about 2 h. Subsequently, the sea breeze progresses beyond the city when the heat island dissipates.
Thereafter, the sea breeze propagates beyond the urban area at a decelerated rate compared to a simulation without an UHI. 相似文献
2.
Maria A. F. Silva Dias Juliana Dias Leila M. V. Carvalho Edmilson D. Freitas Pedro L. Silva Dias 《Climatic change》2013,116(3-4):705-722
Significant positive trends are found in the evolution of daily rainfall extremes in the city of São Paulo (Brazil) from 1933 to 2010. Climatic indices including ENSO, PDO, NAO and the sea surface temperature at the coast near São Paulo explain 85 % of the increasing frequency of extremes during the dry season. During the wet season the climatic indices and the local sea surface temperature explain a smaller fraction of the total variance when compared to the dry season indicating that other factors such as the growth of the urban heat island and the role of air pollution in cloud microphysics need to be taken into account to explain the observed trends over the almost eight decades. 相似文献
3.
A non-hydrostatic, fully compressible, regional-scale numerical model of the atmosphere that includes parameterization of cloud microphysics is run in a two-dimensional mode. It uses two different observed vertical profiles of temperature, relative humidity and wind to simulate the local circulation evolution and impact on convection and nocturnal fog occurrence in São Paulo, Brazil. Theatmospheric behaviour generated by the model is similar to the observations of the two summer days with and without sea breeze progression over the plateau. The convective development occurs in the afternoon of the two experiments but with different features and intensities. In the experiment with sea-breeze progression, there is fog formation over the plateau during the following night, in accordance with the observations. A strong northwesterly flow acting in the lower troposphere, with intensity varying between 7 and 10 m s-1,appears as an inhibiting agent of the sea-breeze progression over the plateau and of convective development in the afternoon and of the nocturnal fog occurrence. In this case, observed gusts during the night are well simulated and appear to be related to the topography. 相似文献
4.
In the present study, we examine the dynamics of a sea-breeze front and the urban heat island interacting with the heavily
urbanized city of Athens. For this reason, simulations were performed with a modified version of the PSU/NCAR Mesoscale Model
(MM5), whereby urban features are considered, and the model results were compared with surface routine meteorological data.
An unrealistic run was also performed, where the city of Athens was replaced by dry cropland and pasture surface, as in the
surrounding area. A delay in the sea-breeze front was found during daytime, together with frictional retardation concerning
its penetration, as well as inland displacement of the heat island as the air moved over the city of Athens. During nighttime,
the wind speed increased over the lower atmosphere in the city centre due to the enhanced urban heat island. 相似文献
5.
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
6.
Response of London’s Urban Heat Island to a Marine Air Intrusion in an Easterly Wind Regime 总被引：1，自引：0，他引：1
Numerical simulations are conducted using the Weather Research and Forecast numerical model to examine the effects of a marine air intrusion (including a sea-breeze front), in an easterly wind regime on 7 May 2008, on the structure of London??s urban heat island (UHI). A sensitivity study is undertaken to assess how the representation of the urban area of London in the model, with a horizontal grid resolution of 1?km, affects its performance characteristics for the near-surface air temperature, dewpoint depression, and wind fields. No single simulation is found to provide the overall best or worst performance for all the near-surface fields considered. Using a multilayer (rather than single layer or bulk) urban canopy model does not clearly improve the prediction of the intensity of the UHI but it does improve the prediction of its spatial pattern. Providing surface-cover fractions leads to improved predictions of the UHI intensity. The advection of cooler air from the North Sea reduces the intensity of the UHI in the windward suburbs and displaces it several kilometres to the west, in good agreement with observations. Frontal advection across London effectively replaces the air in the urban area. Results indicate that there is a delicate balance between the effects of thermal advection and urbanization on near-surface fields, which depend, inter alia, on the parametrization of the urban canopy and the urban land-cover distribution. 相似文献
7.
Urban surface modeling and the meso-scale impact of cities 总被引：4，自引：0，他引：4
V. Masson 《Theoretical and Applied Climatology》2006,84(1-3):35-45
Summary New developments of the international community in modeling the urban canopy surface energy balance are presented and classified
into five main categories: (i) models statistically fit to observations, (ii) and (iii) modified vegetation schemes with or
without drag terms in the canopy, and (iv) and (v), new urban canopy schemes, that present both horizontal and vertical surfaces,
again with or without a drag approach. The advantages and disadvantages of each type of model are explained. In general, the
more the physics are correctly simulated, the more complex are the urban phenomenon that can be addressed, on the other hand
however, the more consuming of computer-time and difficult to couple with atmospheric models the scheme becomes.
Present use of these new models in meso-scale atmospheric models show their ability to reproduce the phenomenon of the urban
heat island (UHI) and some of its consequences – urban breezes, storm initiation, interaction with sea-breeze. Their use opens
up new perspectives, for example in the mitigation of the UHI, or assessment of the role of air-conditioning systems or the
impact of urban dynamics on air pollution.
However, there is need to validate further the different urban models available. In particular it is necessary to compare
model output with urban surface energy balance measurements. An intercomparison exercise involving these urban schemes is
suggested as an efficient way to assess and improve these models. 相似文献
8.
Urban Heat Island and Boundary Layer Structures under Hot Weather Synoptic Conditions: A Case Study of Suzhou City, China 总被引：3，自引：0，他引：3
A strong urban heat island (UHI) appeared in a hot weather episode in Suzhou City during the period from 25 July to 1 August 2007. This paper analyzes the urban heat island characteristics of Suzhou City under this hot weather episode. Both meteorological station observations and MODIS satellite observations show a strong urban heat island in this area. The maximum UHI intensity in this hot weather episode is 2.2℃, which is much greater than the summer average of 1.0℃ in this year and the 37-year (from 1970 to 2006) average of 0.35℃. The Weather Research and Forecasting (WRF) model simulation results demonstrate that the rapid urbanization processes in this area will enhance the UHI in intensity, horizontal distribution, and vertical extension. The UHI spatial distribution expands as the urban size increases. The vertical extension of UHI in the afternoon increases about 50 m higher under the year 2006 urban land cover than that under the 1986 urban land cover. The conversion from rural land use to urban land type also strengthens the local lake-land breeze circulations in this area and modifies the vertical wind speed field. 相似文献
9.
Summary The effects of atmospheric boundary-layer stability on urban heat island-induced circulation are numerically and theoretically
investigated using a nonlinear numerical model (ARPS) and a two-layer linear analytical model. Numerical model simulations
show that as the boundary layer becomes less stable, a downwind updraft cell induced by the urban heat island strengthens.
It is also shown that as the boundary layer becomes less stable, both the height of the maximum updraft velocity and the vertical
extent of the downwind updraft cell increase. Hence, in the daytime with a nearly neutral or less stable boundary layer the
urban heat island-induced circulation can become strong, even though the urban heat island is weak. It is suggested that these
findings can be a mechanism for urban-induced thunderstorms observed in the late afternoon or evening with a nearly neutral
or less stable boundary layer. The boundary-layer stability affects the spatial distribution of scalar concentration through
its influencing urban heat island-induced circulation. Analytical results from a two-layer model with different boundary-layer
stabilities in the lower and upper layers are in general qualitatively consistent with the numerical simulation results, although
the low-level maximum vertical velocity does not change monotonically with lower-layer stability. 相似文献
10.
Lyra Andre Tavares Priscila Chou Sin Chan Sueiro Gustavo Dereczynski Claudine Sondermann Marcely Silva Adan Marengo José Giarolla Angélica 《Theoretical and Applied Climatology》2018,132(1-2):663-682
Theoretical and Applied Climatology - The objective of this work is to assess changes in three metropolitan regions of Southeast Brazil (Rio de Janeiro, São Paulo, and Santos) based on the... 相似文献
11.
Nadiane Smaha Kruk Íria Fernades Vendrame Humberto Ribeiro da Rocha Sin Chan Chou Osvaldo Cabral 《Theoretical and Applied Climatology》2010,99(1-2):115-123
The accurate estimate of the surface longwave fluxes contribution is important for the calculation of the surface radiation budget, which in turn controls all the components of the surface energy budget, such as evaporation and the sensible heat fluxes. This study evaluates the performance of the various downward longwave radiation parameterizations for clear and all-sky days applied to the Sertãozinho region in São Paulo, Brazil. Equations have been adjusted to the observations of longwave radiation. The adjusted equations were evaluated for every hour throughout the day and the results showed good fits for most of the day, except near dawn and sunset, followed by nighttime. The seasonal variation was studied by comparing the dry period against the rainy period in the dataset. The least square linear regressions resulted in coefficients equal to the coefficients found for the complete period, both in the dry period and in the rainy period. It is expected that the best fit equation to the observed data for this site be used to produce estimates in other regions of the State of São Paulo, where such information is not available. 相似文献
12.
The Urban Heat Island Intensity of Paris: A Case Study Based on a Simple Urban Surface Parametrization 总被引：1，自引：0，他引：1
We explore the ability of a simple urban surface parametrization, embedded in a mesoscale meteorological model, to correctly
reproduce observed values of the urban heat island (UHI) intensity, which is defined as the urban-rural surface air temperature
difference. To do so, a simple urban scheme was incorporated into the Advanced Regional Prediction System (ARPS). Subsequently,
a simulation was performed with the coupled model over the wider area of Paris, for a 12-day period in June 2006 that was
characterised by conditions prone to UHI development. Simulated 2-m air temperature was compared with observed values for
urban and rural stations, yielding mean errors of 1.4 and 1.5 K, respectively. More importantly, it was found that the model
also displayed an overall good capability of reproducing the observed temperature differences. In particular, the magnitude (up to 6 K) and timing of the diurnal cycle of the UHI intensity was simulated well, the model
exhibiting a mean error of 1.15 K. As a result, our conclusion is that the ARPS model, extended with simple urban surface
physics, is able to capture observed urban-rural air temperature differences well, at least for the domain and period studied. 相似文献
13.
地表种类的城市化对城市区域的热力结构和局地环流都会产生巨大的影响。利用地面、高空观测资料和MODIS地表覆盖资料,使用耦合城市冠层模式(UCM)的区域中尺度数值模式(WRF),对2013年8月8日福州地区的一次极端高温天气过程进行数值模拟,研究地表利用变化对福州城市热岛效应及其对福州城市区域局地环流的影响。结果表明:地表利用的城市化使得午后城市热岛现象更加明显而夜间热岛效应呈现出减小的趋势;地表利用城市化后,中心城区的近地面风速减小,但城区与山区以及城区与海洋之间的局地热力环流明显加强,促进了山谷风和海陆风环流的发展;同时地表加热效应增强,促进了垂直运动的发展。 相似文献
14.
苏州-无锡-常州城市带热岛效应个例研究 总被引：2，自引：0，他引：2
应用WRF（weather research and forecasting）及其耦合的多层城市冠层模式BEP（building energy parameterization）,对2013年8月13日长江三角洲地区一次高温天气过程进行了模拟.此次过程盛行东南风,风向与苏州-无锡-常州城市带走向一致.模拟结果表明：苏州-无锡-常州城市带热岛效应明显,热岛强度向下游城市逐渐增加;在东南风作用下,三座城市的热岛连成一片,形成了一个更强大的热岛环流.夜晚,边界层逐渐趋于稳定,热岛环流减弱,有利于热岛温度向下游地区输送.热岛效应导致城市边界层高度明显上升.白天太湖产生强盛的湖风对其周边城市影响显著,来自太湖的冷气团导致无锡和常州边界层内热岛强度明显下降,抑制城市热岛向上发展,削弱了无锡与常州两城市热岛间的联系.白天太湖使得无锡和常州边界层高度明显下降. 相似文献
15.
应用WRF(weather research and forecasting)及其耦合的多层城市冠层模式BEP(building energy parameterization),对2013年8月13日长江三角洲地区一次高温天气过程进行了模拟。此次过程盛行东南风,风向与苏州—无锡—常州城市带走向一致。模拟结果表明:苏州—无锡—常州城市带热岛效应明显,热岛强度向下游城市逐渐增加;在东南风作用下,三座城市的热岛连成一片,形成了一个更强大的热岛环流。夜晚,边界层逐渐趋于稳定,热岛环流减弱,有利于热岛温度向下游地区输送。热岛效应导致城市边界层高度明显上升。白天太湖产生强盛的湖风对其周边城市影响显著,来自太湖的冷气团导致无锡和常州边界层内热岛强度明显下降,抑制城市热岛向上发展,削弱了无锡与常州两城市热岛间的联系。白天太湖使得无锡和常州边界层高度明显下降。 相似文献
16.
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
17.
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
18.
Forecasting is the act of predicting unknown future events using available data. Estimating, in contrast, uses data to simulate an actual condition. Brazil is the world’s largest producer of oranges, and the state of São Paulo is the largest producer in Brazil. The “Valência” orange is among the most common cultivars in the state. We analyzed the influence of monthly meteorological variables during the growth cycle of Valência oranges grafted onto “Rangpur” lime rootstocks (VACR) for São Paulo, and developed monthly agrometeorological models for forecasting the qualitative attributes of VACR in mature orchard. For fruits per box for all months, the best accuracy was of 0.84 % and the minimum forecast range of 4 months. For the relation between °brix and juice acidity (RATIO) the best accuracy was of 0.69 % and the minimum forecast range of 5 months. Minimum, mean and maximum air temperatures, and relative evapotranspiration were the most important variables in the models. 相似文献
19.
城市热岛效应的研究进展与展望 总被引：24，自引：1，他引：23
随着世界各国城市化的进展,城市热岛效应已经成为一个跨学科领域的问题,受到包括大气环境、区域气候、水文和生态等多学科科学家的关注。在过去半个多世纪中,城市热岛问题的研究获得了相当丰富的研究成果,通过对这些成果的综合分析,归纳出城市热岛研究中采用的3类主要方法——观测(外场试验和遥感技术)、数值模拟以及实验室仿真法。系统地回顾了城市热岛效应的研究历史,重点对与城市热岛关系最密切的城市边界层、热岛环流与复杂地形的相互作用以及能量平衡研究所取得的成果进行了总结和评述。最后对城市热岛问题未来8个可能的研究方向进行了探讨,其中,包括沿海和复杂地形附近的城市热岛问题、城市群间热岛环流的相互作用、城市化与空气污染问题、城市热岛效应对平均降水的影响、城市化对雾和闪电的影响、城市天气预报的精细化、城市气候变化预测以及城市热岛效应减缓方案的制定,并对其发展前景进行了粗略的展望。 相似文献
20.
The study has analyzed influence of an atmospheric circulation on urban heat island (UHI) and urban cold island (UCI) in Poznań. Analysis was conducted on the basis of temperature data from two measurement points situated in the city center and in the ?awica airport (reference station) and the data concerning the air circulation (Nied?wied?’s calendar of circulation types and reanalysis of National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR)). The cases with UHI constitute about 85 % of all data, and UCI phenomena appear with a frequency of 14 % a year. The intensity of UHI phenomenon is higher in the anticyclonic circulation types. During the year in anticyclonic circulation, intensity of UHI is 1.2 °C on average while in cyclonic is only 0.8 °C. The occurring of UHI phenomena is possible throughout all seasons of the year in all hours of the day usually in anticyclonic circulation types. The cases with highest UHI intensity are related mostly to nighttime. The cases of UCI phenomena occurred almost ever on the daytime and the most frequently in colder part of the year together with cyclonic circulation. Study based on reanalysis data indicates that days with large intensity of UHI (above 4, 5, and 6 °C) are related to anticyclonic circulation. Anticyclonic circulation is also promoting the formation of the strongest UCI. Results based on both reanalysis and the atmospheric circulation data (Nied?wied?’s circulation type) confirm that cases with the strongest UHI and UCI during the same day occur in strong high-pressure system with the center situated above Poland or central Europe. 相似文献