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1.
应用城市冠层模式研究建筑物形态对城市边界层的影响 总被引：5，自引：1，他引：4
文中将城市冠层模式耦合到南京大学城市尺度边界层模式中,通过模拟对比发现,耦合模式对城市地区气温模拟结果更接近于观测值,尤其是对城市地区夜间气温模拟的改进.运用改进耦合模式通过多个敏感性试验的模拟,从城市面积扩张、建筑物高度增加、建筑物分布密度变化等角度研究城市建筑物三维几何形态变化对城市边界层及城市气象环境的影响,试验结果表明:(1)城市面积扩张使得城市下垫面的热通量增大,热力湍流活动增强,动量通量输送增强,城市湍能增大,湍流扩散系数变大,城市气温升高,且对不同时刻城市区域大气层结稳定度均有不同程度的影响.(2)建筑物高度增加增大了城市下垫面的粗糙度和零平面位移.同时也增大了城市街渠高宽比.城市建筑物越高,白天城市地区地表热通量越小,城市上空大气温度越低,平均风速减小,湍能减小;夜间由于高大建筑物释放储热比低矮建筑物要多,其热力湍流相对活跃,地表热通量增大,使得城市区域气温较高.(3)建筑物密度增大,会减小城市下垫面的粗糙度同时增强街渠对辐射的影响.建筑物密度增大在白天会减小地表热通量和动量通量,使城市气温降低,平均风速增大,城市湍流活动能力减弱;夜间城市释放较多储热使得气温较高. 相似文献
2.
多层城市冠层模式的建立及数值试验研究 总被引：4，自引：1，他引：3
为在城市气象数值模拟中更好地体现由城市发展引起的下垫面土地利用改变及人为活动对大气过程的影响,建立了基于建筑物三维分布的多层城市冠层模式,冠层内动力方程组考虑了建筑物冠层拖曳力的作用及雷诺应力的影响,通过引入建筑物宽度、间距以及垂直分布密度指数等建筑物形态特征参数,以更好地体现城市复杂地表对大气温度、湿度及动量方程的影响.同时,该模式分屋顶、4个侧壤及地面分别考虑辐射及能量平衡求解表面温度,计算各表面与大气的通量交换,并考虑辐射阴影效应、冠层内部各个面之间的可视因子、以及与冠层内建筑物密度指数、可视因子等相关的多重反射辐射导致的辐射截陷作用.模式的离线检验结果表明:(1)冠层模式计算风廓线与风洞实验测量数据吻合良好;(2)离线冠层模式能够模拟实际小区的风速、温度垂直廓线,并能够较好地体现小区内气温日变化.冠层模式与区域边界层模式耦合检验结果表明:(1)耦合模拟的近地面(2 m处)气温及地表温度的结果明显优于传统的水泥平板方案,尤其是在夜间,水泥平板方案与实测气温最大偏差4 K左右,耦合模拟方案为1-2 K;(2)耦合模拟方案考虑了建筑物对冠层之上的拖曳力影响以及建筑物形态结构对雷诺应力的影响,风速(10 m处)计算结果与观测值相差约在1 m/s,水泥平板方案偏差3 m/s左右. 相似文献
3.
城市建筑动力学效应对对流边界层影响的敏感性试验 总被引：3，自引：1，他引：2
本文将大涡模拟应用于城市对流边界层(CBL)湍流结构和流场特征的研究,在大涡模式中,拖曳系数取与建筑物高度及建筑物高度标准差有关的表达式以考虑次网格建筑物对风速和湍流动能(TKE)的面积平均影响.模拟结果表明,由于城市建筑物对气流的拖曳作用,使建筑物冠层及整个CBL内风速大幅度减小,城市冠层内部风速减小尤为明显,在夹卷层内,风速有一明显的跃变.在边界层中部对流运动已经发展成为较强的热泡,城市建筑物的动力学效应使热泡的水平尺度增大,CBL内平均上升气流速度和下沉气流速度减小,同时使CBL中上升气流所占比例比平坦地面增大.城市建筑物使CBL低层热通量、动量通量、速度方差和位温方差明显增大,但对近地层高度以上的湍流量影响不大. 相似文献
4.
5.
运用WRF模式,选取考虑城市冠层结构(UCM算例)及不考虑城市冠层(NOUCM算例)两种城市下垫面参数化方案,对南京2010年夏季晴天小风典型天气条件下的城市热环境以及不同下垫面的边界层特征进行了模拟研究。结果表明:1)UCM方案模拟结果与实际情况较为吻合。其中2 m气温的模拟有较大的改进,模拟结果明显高于NOUCM方案,与观测更为吻合,同时更好地模拟出了冠层建筑物对于近地层风速的拖曳,10 m风速的模拟有非常明显地提高。2)UCM方案较好地模拟出了城市的三维热岛分布。由于建筑物地表对辐射的截留,白天14时(北京时间,下同)热岛较强,地面2 m高度处热岛范围较大,热岛面积大约为120 km2,强度为2℃。同时建筑物的存在使得城市湍流动能更大,向上的垂直扩散增加,距地面20 m时,依然能看出明显的热岛效应,热岛强度为1.5℃。距地面55 m处,UCM模拟所得的热岛范围缩小,热岛强度为1.1℃。UCM模拟所得的白天地表热量的扩散影响可达143 m,02:00 2 m处热岛最强为2℃,热岛影响也可达70 m以上。3)不同下垫面呈现出了不同的边界层特征,城市冠层结构对周边下垫面边界层结构存在程度不等的影响,14:00城市区域的湍流混合更强,城市边界层高度升高100 m左右,02:00,城市冠层结构的存在,导致近郊庄稼下垫面及紫金山植被下垫面的稳定逆温层结明显减弱。 相似文献
6.
城市建筑物对边界层结构影响的数值试验研究 总被引：5，自引：5，他引：5
在区域边界层模式的数值模拟中引入建筑物的影响,与实际观测的对比表明,模拟结果能较好地体现建筑物对城市风场的影响,提高了模拟性能。本研究根据城市形态特征,设计不同建筑物高度和密度的敏感性试验,结果表明:建筑物一般会使城市地区风速减小,风速最大可减小1.6 m/s,易引起低层气流的辐合。湍流动能中的机械产生作用增加,湍流交换加强,大气层结的不稳定性增大,混合层高度增加。地表和大气之间动量交换被削弱;日间热量交换减弱,夜间热量交换增强。这些变化表明,建筑物对城市气流及边界层结构的影响十分明显,尤其在风速较大的时候。 相似文献
7.
本文运用已建精细城市PBL模式，用拖曳力法考虑城市建筑物的影响，并以北京前三门地段板房为例，通过8个数值试验具体研究了建筑物对气象场的影响。结果表明：前三门地段板房的有无对风速、湍能和NOx浓度的影响较明显。有板房比没有板房时30m处水平总风速减少0．03～0．10m／s，湍能增大O．02～0．14m^2／s^2。板房对水平总风速的影响大于0．01m／s的范围为：迎风向和背风向约400～500m，侧风向约100～200m；垂直方向的影响高度约为150m。在30m高度附近影响最大。对湍流动能的影响范围与风速的类似。对NOx浓度的影响以地面为最大，其影响程度及影响范围和板房与污染源的相对位置以及板房与周围建筑物的距离有关。总之，在高分辨的边界层模式中，用拖曳力法考虑城市建筑物的影响是可行和必要的。 相似文献
8.
城市冠层上下大气湍流特征分析 总被引：2，自引：0，他引：2
利用兰州市榆中县城市冠层架设的3台涡动相关仪(EC)观测大气湍流资料,分析了城市冠层上下不同下垫面湍流通量和不同风向范围内湍流动能变化特征,之后对城市冠层上下3台EC观测湍流动能最小、最大分布方向上分别对应的最小最大湍流动能的风速谱进行了研究,进一步检验了局地相似理论在城市冠层上下的适用性。结果表明:(1)城市冠层之上水泥、砖石等构成下垫面和城市冠层之内草坪下垫面观测感热通量、摩擦速度较为接近,观测潜热通量、CO2通量在白天差异明显。(2)城市冠层之上的湍流动能总体上大于冠层之内,冠层之上气流来向的上风向较为开阔时湍流动能较大,而冠层之内气流来向的上风向为街道口时湍流动能较大。(3)城市冠层之上的湍涡尺度大于冠层之内,城市冠层小尺度湍涡风速谱在惯性副区基本符合-2/3次方关系,且准各向同性,大尺度湍涡风速谱在惯性副区不符合-2/3次方关系,且各向异性。(4)不稳定层结下,城市冠层上下无量纲速度方差与稳定度基本满足1/3次方局地相似关系,稳定层结下不满足;城市冠层上下无量纲温度、湿度、CO2浓度方差在所有层结下均不满足-1/3次方局地相似关系。(5)近中性层结下,城市冠层上下u、v、w方向无量纲速度方差分别为3.52,3.03,1.49和2.62,2.22,1.50。 相似文献
9.
城市小区建筑物和屋顶绿化对小区气象环境影响的数值模拟研究 总被引：1，自引：1，他引：0
为了研究城市小区建筑物和屋顶绿化对小区气象环境影响,利用USDSM(城市小区气象与污染扩散数值模式)对杭州市一临钱塘江小区进行敏感性试验。结果表明:(1)小区建筑物的拖曳、阻尼和摩擦作用造成敏感小区内10 m高度平均水平风速减小0.56 m·s-1;对风速的影响范围:迎风向为500 m,背风向为500~600 m,侧风向为200 m,影响高度达到建筑物群平均高度的两倍以上。(2)小区建筑物存在导致低层污染扩散能力减弱,平均污染物浓度达到初始浓度0.01的时间延迟7.6 min。(3)100%的屋顶绿化面积可造成敏感小区平均地表温度下降0.56℃;5 m高度平均气温下降0.70℃;小区平均建筑物高度处气温下降0.94℃。敏感小区内10 m高度平均水平风速增加0.14 m·s-1;小区建筑物下游水平风速显著减小,影响范围达到了600~800 m。 相似文献
10.
高大建筑物影响城市粗糙副层流场特征的数值研究 总被引：1，自引：1，他引：0
用数值模拟方法研究了高大建筑物对城市粗糙副层气流场特征的影响。数值模式采用基于雷诺平均纳维—斯托克斯方程组的应用计算流体力学FLUENT软件,次网格湍流参数化选用k-ε闭合方案。建筑物用立方体表示,并规则排列于模拟区域内。通过改变高大建筑物的数量与位置,对建筑物阵列内及其上空的气流特征进行了多个算例的数值模拟。依据模拟结果计算获得建筑物区域的面积平均风速廓线,结果表明各算例的粗糙副层风速廓线各不相同。运用动力学方法由风速廓线计算出各算例的零平面位移高度和粗糙度,并与几种计算零平面位移高度和粗糙度的形态学方法进行了比较检验。结果表明两种形态学方法(Ba、Ma)计算所得的零平面位移高度与动力学方法计算结果很接近,但对于粗糙度而言,几种形态学方法的计算结果都明显偏高。 相似文献
11.
An urban boundary layer model (UBLM) is improved by
incorporating the effect of buildings with a sectional drag coefficient and
a height-distributed canopy drag length scale. The improved UBLM is applied
to simulate the wind fields over three typical urban blocks over the Beijing
area with different height-to-width ratios. For comparisons, the wind fields
over the same blocks are simulated by an urban sub-domain scale model
resolving the buildings explicitly. The wind fields simulated from the two
different methods are in good agreement. Then, two-dimensional building
morphological characteristics and urban canopy parameters for Beijing are
derived from detailed building height data. Finally, experiements are
conducted to investigate the effect of buildings on the wind field in
Beijing using the improved UBLM. 相似文献
12.
Large eddy simulation and study of the urban boundary layer 总被引：7，自引：1，他引：6
13.
Study on Effects of Building Morphology on Urban Boundary Layer Using an Urban Canopy Model 
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下载免费PDF全文 An urban canopy model is incorporated into the Nanjing University Regional Boundary Layer Model. Temperature simulated by the urban canopy model is in better agreement with the observation, especially in the night time, than that simulated by the traditional slab model. The coupled model is used to study the effects of building morphology on urban boundary layer and meteorological environment by changing urban area, building height, and building density.It is found that when the urban area is expanded, the urban boundary layer heat flux, thermal turbulence, and the turbulent momentum flux and kinetic energy all increase or enhance, causing the surface air temperature to rise up. The stability of urban atmospheric stratification is affected to different extent at different times of the day.When the building height goes up, the aerodynamic roughness height, zero plane displacement height of urban area, and ratio of building height to street width all increase. Therefore, the increase in building height results in the decrease of the surface heat flux, urban surface temperature, mean wind speed, and turbulent kinetic energy in daytime. While at night, as more heat storage is released by higher buildings, thermal turbulence is more active and surface heat flux increases, leading to a higher urban temperature.As the building density increases, the aerodynamic roughness height of urban area decreases, and the effect of urban canopy on radiation strengthens. The increase of building density results in the decrease in urban surface heat flux, momentum flux, and air temperature, the increase in mean wind speed, and the weakening of turbulence in the daytime. While at night, the urban temperature increases due to the release of more heat storage. 相似文献
14.
MM5模式中城市冠层参数化方案的设计及其数值试验 总被引：15，自引：5，他引：15
文中在综合国外一些较先进的中尺度模式城市作用参数化方案的基础上 ,从城市下垫面结构对城市边界层大气作用的物理机制及实际应用两方面出发 ,对城市下垫面结构和人为活动等因素对边界层结构的影响及中尺度模式中城市化作用的合理体现等问题进行了较全面的考虑 ,改进和设计出能够较全面、细致地描述城市结构对大气边界层动力、热力结构的影响 ,且适合中尺度模式结构特点的城市冠层参数化方案 (UCP) ,并实现了其与MM5模式的耦合。进行了耦合后的UCP方案及采用原城市作用方案的MM5模式对BECAPEX试验期间北京地区气象条件多重嵌套细尺度进行了模拟试验 ,并与观测结果对比 ,结果表明 :相比于MM 5模式中原有表示城市作用的参数化方案来讲 ,设计的UCP方案在很大程度上提高了MM 5模式对城市边界层热力和动力结构的模拟能力。 相似文献
15.
A multilayer one-dimensional canopy model was developed to analyze the relationship between urban warming and the increase
in energy consumption in a big city. The canopy model, which consists of one-dimensional diffusion equations with a drag force,
has three major parameters: building width, distance between buildings, and vertical floor density distribution, which is
the distribution of a ratio of the number of the buildings that are taller than some level to all the buildings in the area
under consideration. In addition, a simplified radiative process in the canopy is introduced. Both the drag force of the buildings
and the radiative process depend on the floor density distribution. The thermal characteristics of an urban canopy including
the effects of anthropogenic heat are very complicated. Therefore, the focus of this research is mainly on the basic performance
of an urban canopy without anthropogenic heat. First, the basic thermal characteristics of the urban canopy alone were investigated.
The canopy model was then connected with a three-dimensional mesoscale meteorological model, and on-line calculations were
performed for 10 and 11 August, 2002 in Tokyo, Japan. The temperature near the ground surface at the bottom of the canopy
was considerably improved by the calculation with the canopy model. However, a small difference remained between the calculation
and the observation for minimum temperature. Deceleration of the wind was well reproduced for the velocity at the top of the
building by the calculation with the canopy model, in which the floor density distribution was considered. 相似文献
16.
Bruno Bueno Leslie Norford Grégoire Pigeon Rex Britter 《Boundary-Layer Meteorology》2011,140(3):471-489
A scheme that couples a detailed building energy model, EnergyPlus, and an urban canopy model, the Town Energy Balance (TEB), is presented. Both models are well accepted and evaluated within their individual scientific communities. The coupled scheme proposes a more realistic representation of buildings and heating, ventilation and air-conditioning (HVAC) systems, which allows a broader analysis of the two-way interactions between the energy performance of buildings and the urban climate around the buildings. The scheme can be used to evaluate the building energy models that are being developed within the urban climate community. In this study, the coupled scheme is evaluated using measurements conducted over the dense urban centre of Toulouse, France. The comparison includes electricity and natural gas energy consumption of buildings, building façade temperatures, and urban canyon air temperatures. The coupled scheme is then used to analyze the effect of different building and HVAC system configurations on building energy consumption, waste heat released from HVAC systems, and outdoor air temperatures for the case study of Toulouse. Three different energy efficiency strategies are analyzed: shading devices, economizers, and heat recovery. 相似文献
17.
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
18.
Syed Zahid Husain Stéphane Bélair Jocelyn Mailhot Sylvie Leroyer 《Boundary-Layer Meteorology》2013,147(3):525-551
A new approach to improve the representation of surface processes in the Global Environmental Multiscale (GEM) atmospheric model associated with the exchanges between the urban canopy and the atmosphere is presented. Effects of the urban canopy on the evolution of surface-layer wind, temperature, moisture, and turbulence are directly parametrized in order to allow realistic interactions between the canopy elements (i.e., roofs, roads, and walls) and the atmosphere at GEM’s multiple vertical levels that are positioned inside the canopy. Surface energy budgets as implemented in the Town Energy Balance (TEB) scheme have been used to determine temperatures of the urban canopy elements for the proposed multilayer scheme. Performance of the multilayer scheme is compared against standard implementations of the TEB scheme for one nighttime intensive observation period of the Joint Urban 2003 experiment held in Oklahoma City, USA. Although the new approach is found to have a negligible impact on urban surface-layer wind profiles, it improves the prediction of near-neutral nocturnal profiles of potential temperature close to the surface. The urban heat island effect is simulated with a better accuracy by the multilayer approach. The horizontal temperature gradient across the central business district of the city along the direction of flow is also reasonably well captured by the proposed scheme. 相似文献