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马力 《沙漠与绿洲气象(新疆气象)》1990,(11)
一、引言《风的分布律》一文的作者,在文献〔1〕中从统计力学的观点出发,由实际资料计算得出了北半球大气从地面到100hPa各标准等压面上的风速分布率符合n=2的Γ分布.也就是说,在各等压面上,风速出现于C→C+1者的相对面积是多少,它符合n=2的Γ分布.为了检验这种风速分布的守恒性,文献〔1〕还选做了一次中国发生寒潮时的连续6天的500hPa风速分布,发现其仍然 相似文献
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利用1981—2014年我国资料齐全的93个高空气象观测站(距离雷达300、600、900 m高度)的探空风资料,按照气象地理区划,借助GIS分析了边界层内不同高度风速及其趋势的时空变化,得到以下结论:300～900 m,东北和华北地区累年平均风速较大,西南和西北地区累年平均风速较小;边界层内各高度同一地区平均风速的月变化趋势基本一致,但各地区季节风速变化不同,同一地区月平均风速的年较差随高度上升而增大;300 m.各地区年平均风速均显著减小:在600和900 m.华北、西北、华中地区年平均风速呈增加趋势,东北地区年平均风速呈减小趋势,但均未通过显著性水平检验;各高度年平均风速空间分布均为东北地区较大,尤其大兴安岭和东北平原地带;从沿海到内陆,由东至西风速逐渐减小;在300 m.全国年平均风速以减小趋势为主;在600 m,全国大部分地区年平均风速呈增加趋势,尤其是中部、西北和华东沿海地区;在900 m高度,全国年平均风速变化趋势呈现由边界向内部的包围态势,中心地区呈增加趋势,边界地区均呈减小趋势,但是通过显著性水平检验的地区不多。 相似文献
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一、引言近年来,在诸如大气污染模式、建筑物风荷载的估计以及风能分析等等这样一些实际应用中,对于使用特殊分布进行风速资料的拟合已有许多研究,而目前考虑最多的是韦伯(Weibull)分布. 大量研究结果表明,韦伯分布由于它的伸缩性和使用方便(只需估计2～3个参数),常用来作为拟合实际风速分布的理论模型,而且通常能够给出近似的却能令人满意的结果.如果实测风速满足一定条件,则韦伯分布就是一个拟合风速频率的数学函数. 相似文献
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用Monte-Carlo模拟方法建立了上海的台风年最大风速概率分布，由此推算的30a、50a一遇风速（韦伯尔分布）和实测风速值接近。表明由Monte-Carlo模拟方法得到的台风年最大风速概率分布较为合理，在东南沿海台风多发区域，该方法是产生年最大风速概率分布的有力工具。 相似文献
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精细准确预报大风风速对于风功率预报和风灾防御具有重要意义。本文以上海市域为研究区域,基于形态学方法估算上海市域空气动力学粗糙度分布,并通过近地层分层风速插值方法推算上海市域10 m高度精细风速分布。针对2016年1月23日20时—24日20时一次大风过程开展实证检验,对比分析降尺度模拟风速、地面实测风速、ECMWF预报10 m风速的空间分布、时间变化以及垂直廓线特征。结果表明,该方法可以较好地模拟上海市域风速大小的精细空间分布,模拟精度总体上表现为中心城区精度高、郊区精度稍低,但相比于ECMWF预报10 m风速分布有了明显提高,可以为风速的精细化预报提供技术支撑。 相似文献
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沿海地区的风速在海陆交界处变化极为复杂,其风速规律研究对近海风电场的发展有着极为重要的作用。本文采用江苏沿海40 km范围内38个观测站的2009年7月1日—2011年6月30日近2 a的平均风速实测资料,利用旋转经验正交函数(REOF)对沿海平均风速开展主分量特征分析,进而将江苏沿海地区划分为南北两个区域,开展江苏沿海风速衰减规律分析,风速随沿海向内陆呈现e指数衰减特征。在此基础上,构建了江苏沿海南北两个区域的平均风速在空间上的分布方程,并开展了拟合精度检验和可靠性分析。研究结果表明海陆地形影响的范围大小与海岸线上的风速并非完全成正相关的关系而存在临界值,南区、北区风速临界值分别为18. 2 m·s~(-1)和14. 6 m·s~(-1)。 相似文献
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应用蓝金模式模拟了纯气旋性旋转的多普勒雷达径向速度特征,还模拟了不同环境风向和吹向台风中心的辐合风对台风多普勒速度特征的影响。在此基础上,提出了雷达实测台风速度的特征和不同环境风向的速度数值模拟图进行比较,从而提取出相应环境风信息的方法,并应用这种环境风信息来判断台风的移动路径。通过对台风实例分析,特别是在台风发生转折的关键时刻,该方法都能够较准确地判断环境风转折的多普勒速度特征。应用多普勒雷达径向速度图像与不同环境风向模拟图像进行比较的方法,能够实时(雷达观测时间间隔仅为6 min)监测到环境气流的方向及其变化,比较准确地监测台风的移动路径,这是其他大尺度气象资料难以做到的。分析表明:环境风转向变化的现象在前,台风发生转折的现象在后,对台风路径的短时预报具有一定应用价值。 相似文献
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By use of the small parameter expansion method, the nonlinear planetary boundary layer (PBL) is studied in this paper. The PBL is divided into the surface layer and the Ekman layer, which is divided into several sublayers. In the surface-layer, the eddy coefficient K is taken as a linear function of height; in the Ekman layer, different constant K values are taken within different sublayers: these values are determined from O'Brien's formula (O'Brien, 1970) approximately. Under the upper and lower boundary conditions and the continuity conditions of the wind velocities and turbulent stresses at each boundary between sublayers, analytical expressions for wind velocity in all sublayers and the vertical velocity at the top of the PBL are obtained. A specific example of steady axisymmetrical circular high and low pressure areas is analysed, and some new conclusions are obtained. The results are in better agreement with reality than previous results. This example also shows that the vertical velocity at the top of the PBL caused by friction approaches zero near the center of a high or low pressure system for this model, but attains its maximum absolute values near the center of the high or low pressure area for Wu's (1984) model. This is due to the fact that in our model, the geostrophic wind speed near the center of this specific vortex approaches zero, which causes the wind shear and the friction effect to be very weak. Therefore the wind distribution in the PBL is very sensitive to the type of eddy coefficient. 相似文献
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利用中国风能资源专业观测网2009年5—10月各高度层（10、30、50、70 m）的10 min观测数据分析了全国近地层风速及风功率密度的时空、方位及梯度分布特征。结果表明：①全国各地区平均风功率密度基本为1652 W/m2,西北地区以及东南沿海地区风能资源更为丰富;② 5月和10月两个月风能资源的可开发量较大,其中北方地区一般5月较大,而南方地区10月较大;③全国各地大体上呈现西北内陆、东北、华北地区刮偏西北风,东部沿海地区刮偏东南风,云贵地区盛行西南风的趋势;④从不同梯度情况来看,越往高层风能资源的可开发量越大;⑤从全国风能资源的日变化情况来看,一般从08：00—20：00风能资源比较丰富,其中15：00平均风功率密度和平均风速达到极大值,但不同地区不同时段风能资源分布还存在一定差异。 相似文献
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Wind shear reflects that the wind field is not uniform, which is one of the primary factors which make the retrieval of the wind field difficult. Based on volume velocity process(VVP) wind field retrieval technique, the intensity of wind shear is identified in this paper. After analyzing the traditional techniques that rely on the difference of radial velocity to identify wind shear, a fixed difference among radial velocities that may cause false identification in a uniform wind field was found. Because of the non-uniformity in wind shear areas, the difference of retrieved results between surrounding analysis volumes can be used as a measurement to show how strong the wind shear is. According to the analysis of a severe convective weather process that occurred in Guangzhou, it can be found that the areas of wind shear appeared with the strength significantly larger than in other regions and the magnitude generally larger than4.5 m/(s·km). Besides, by comparing the variation of wind shear strength during the convection, it can be found that new cells will be more likely to generate when the strength is above 3.0 m/(s·km). Therefore, the analysis of strong wind shear's movement and development is helpful to forecasting severe convections. 相似文献
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We conduct wind-tunnel experiments on three different uniform roughness arrays composed of sparsely distributed rectangular
cylinders for the estimation of surface parameters. Roughness parameters such as the roughness length z
0 and zero-plane displacement d are extracted using a best-fit approximation of the measured wind velocity. We also perform a large-eddy simulation (LES)
to confirm that four sampling points are sufficient to surrogate a space average above the canopy layer of the sparse roughness
arrays. We propose a new morphological model from a systematic analysis of experimental data on the arrays. The friction velocity
predicted by the proposed model agrees well with the peak value of the measured Reynolds shear stress ${(-\left<\overline{u'w'}\right>)^{0.5}}${(-\left<\overline{u'w'}\right>)^{0.5}}. The proposed model is further validated in an additional wind-tunnel experiment conducted on a scaled configuration of a
real urban area exposed to four wind directions. The proposed model is found to perform very well particularly in the estimation
of the friction velocity, readily leading to a better estimation of turbulence, which is essential for an accurate prediction
of pollutant dispersion. 相似文献
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A Simple Model for Spatially-averaged Wind Profiles Within and Above an Urban Canopy 总被引：2，自引：2，他引：0
This paper deals with the modelling of the flow in the urban canopy layer. It critically reviews a well-known formula for
the spatially-averaged wind profile, originally proposed by Cionco in 1965, and provides a new interpretation for it. This
opens up a number of new applications for modelling mean wind flow over the neighbourhood scale. The model is based on a balance
equation between the obstacle drag force and the local shear stress as proposed by Cionco for a vegetative canopy. The buildings
within the canopy are represented as a canopy element drag formulated in terms of morphological parameters such as λ
f
and λ
p
(the ratios of plan area and frontal area of buildings to the lot area). These parameters can be obtained from the analysis
of urban digital elevation models. The shear stress is parameterised using a mixing length approach. Spatially-averaged velocity
profiles for different values of building packing density corresponding to different flow regimes are obtained and analysed.
The computed solutions are compared with published data from wind-tunnel and water-tunnel experiments over arrays of cubes.
The model is used to estimate the spatially-averaged velocity profile within and above neighbourhood areas of real cities
by using vertical profiles of λ
f
. 相似文献
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笛卡儿坐标系的双多普勒天气雷达三维风场反演技术 总被引：27，自引：9，他引：27
文中研究了笛卡尔坐标系下双多普勒天气雷达三维风场反演技术 ,提出了包括雷达原始资料的预处理 ,空间插值以及可靠性检验的新方法 ,提高了反演结果的可信度和精确度。使用模拟的双多普勒雷达体扫资料进行了反演试验 ,结果表明 :本文的方法能够比较真实地反映风场的三维结构 ,可以用于真实风场的反演。 相似文献
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逆风区的回波演变与强对流天气的结构分析 总被引：2，自引：0，他引：2
为研究逆风区回波结构的演变与中尺度强对流天气发生发展的关系,分析了2005年4月30日和6月22日在江西省境内有逆风区现象的强对流天气的多普勒雷达回波特征,对逆风区的回波强度与速度的演变进行对比分析后认为：逆风区不仅是暴雨判据,也是强对流天气的判据。逆风区的伸展高度一般较高,有逆风区的存在基本上都伴有剧烈的天气过程,只要逆风区的结构一直存在,强回波的反射率因子就不会减弱。本文提出了一种逆风区的三维结构模型,逆风区回波反映了强对流的生消结构,逆风区实为前方辐合上升、后方下沉的涡管结构,它是认识强对流天气系统三维结构的重要信息。 相似文献