共查询到18条相似文献,搜索用时 156 毫秒
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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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本文讨论了韦伯函数在估算风速频率分布上的应用,并提出了由原始风记录来估算韦伯参数(尺度参数c和形状参数k)的方法。把这些方法与近来有人提出的使用平均风速和最大风速作为基本数据的所谓“方根正态分布”作过对比,结果表明,在风速分布的拟合过程中,韦伯分布所导致的标准差比“方根正态分布”的来得小。并且它还具有另一个优点,即根据某一高度上所得到的c和k值可以推算出另一高度上的c和k值。 相似文献
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利用广东省86个国家气象观测站建站以来近70a的逐月最大风速序列和近20a(1999—2018年)的逐月最大风速序列,基于POT抽样法,分别采用三参数广义帕累托分布函数对各站的重现期风速进行了概率计算,计算过程中三参数广义帕累托分布函数分别采用矩估计(MOM)、极大似然估计(MLE)、似然矩估计(LM)和概率权矩估计(PWM)等4种参数估计方法,结合表征参数估计优良性的指标:均方根误差RMSE、拟合相对偏差和显著性水平为0.05的科莫戈洛夫检验拟合适度指标K_f对拟合效果进行检验,结果表明:基于POT抽样的概率权矩估计(PWM)拟合效果最好。 相似文献
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Weibull分布参数估计方法及其应用 总被引:12,自引:1,他引:12
Weibull分布对于年最大风速、波高、降水量等气候极值具有很高的拟合精度和很强的适应性。本文给出四种Weibull分布参数估计方法:概率权重矩法(PWM)、最小二乘法(LSM)、最大似然法(M-L)和适线法(FIT),并通过统计检验进行拟会精度比较。结果表明:PWM、LSM和M-L法对样本的拟合精度都比较高,其中PWM法计算最为简便,LSM和M-L法采取a0的试设法,大大简化了计算过程;经验累积频率公式更适合于Weibull分布;三参数计算精度较二参数高得多。 相似文献
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该文用二参数Weibull分布函数对武汉地区3年近地层5~146 m塔层6个层次的风速进行拟合,主要分析了分布函数中形状参数和尺度参数的获取方法。通过与实际值的对比,表明经验法优于最小二乘法。运用此方法,对近地层风能进行估算,其结果与常规方法的最大相对误差为2.7%,最小仅为0.1%。并在最后讨论了风能和垂直分布规律。 相似文献
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We analyzed the frequency distribution characteristics of wind speeds occurring at different offshore sites within a range of 0–200 km based on the sea surface wind data captured via buoys and oil platforms located along the east coast of Guangdong Province. The results of the analysis showed that average wind speed measured for each station reached a maximum in winter while minima occurred in summer, corresponding to obvious seasonal variation, and average wind speed increased with offshore distance. The prevailing wind direction at the nearshore site is the easterly wind, and the frequency of winds within 6–10 m s–1 is considerable with that of winds at > 10 m s–1. With the increase of the offshore distance, the winds were less affected by the land, and the prevailing wind direction gradually became northerly winds, predominately those at > 10 m s–1. For areas of shorter offshore distance (< 100 km), surface wind speeds fundamentally conformed to a two-parameter Weibull distribution, but there was a significant difference between wind speed probability distributions and the Weibull distribution in areas more than 100 km offshore. The mean wind speeds and wind speed standard deviations increased with the offshore distance, indicating that with the increase of the wind speed, the pulsation of the winds increased obviously, resulting in an increase in the ratio of the mean wind speed to the standard deviation of wind speed. When the ratio was large, the skewness became negative. When a relatively great degree of dispersion was noted between the observed skewness and the skewness corresponding to the theoretical Weibull curve, the wind speed probability distribution could not be adequately described by a Weibull distribution. This study provides a basis for the verification of the adaptability of Weibull distribution in different sea areas. 相似文献
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Regional analysis of wind climatic erosivity factor: a case study in fars province, southwest Iran 总被引:1,自引:0,他引:1
Wind erosion climatic erosivity is a measure of the climatic tendency to produce conditions conducive to wind erosion. This research develops a method to determine the regional climate’s tendency to cause wind erosion on the basis of a physically based climatic factor (CE) and linear moment analysis (L-moments) in Fars province, southwest Iran. CE is calculable from wind speed quantiles and other available meteorological data. The wind quantiles can be estimated by a frequency analysis of the available wind data. Wind speed data are often either not available or are of short record length, and thus, CE estimates from such data have large standard errors. In such a situation, data from several sites can be used to estimate wind speed quantiles at each site based on a regional frequency analysis. Monthly averages of maximum daily wind speed of 19 meteorological stations in Fars province were used for regional analysis. Based on L-moment analysis, two homogeneous regions were determined. Regional wind speed quantiles were calculated, and the results were used to calculate CE values for two 6-month wet and dry periods for each homogeneous region. Furthermore, CE values were estimated for each station in the study area using a Weibull distribution, and the results were compared with the regional-based CE values. It showed that CE values estimated using the regional-based approach have smaller sampling variance compared to those obtained from the Weibull method. The proposed method can be used to evaluate the regional risk of wind erosion in arid and semi-arid environments. 相似文献
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卫星反演海面风场资料能够弥补海上气象测风资料缺乏的不足,对近海风能资源评估具有重要意义。通过ASCAT(Advanced Scatterometer)风速数据与美国及中国近海岸浮标测风资料的对比分析,结果表明,ASCAT风速的均方根误差为1.27 m·s-1。比较利用近海岸浮标逐小时风速及与其相匹配ASCAT瞬时风速计算的各项风能参数,得出ASCAT与浮标的平均风速和风功率密度的残差分别在±0.5 m·s-1和±50 W·m-2以内,该残差占浮标计算结果的比例分别在±8%和±12%以内。使用ASCAT风速资料拟合的Weibull分布函数与浮标的结果较吻合。因此,ASCAT风速资料也能够为海上风能资源评估提供有用的风能参数信息。最后使用ASCAT瞬时风速数据分析了中国近海10 m及70 m高度处的风能资源的空间分布特征,结果表明,台湾海峡平均风速和风功率密度最大。 相似文献
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南京地面风速概率分布律的城乡差异 总被引:1,自引:0,他引:1
根据南京气象站及其周边3个乡村自动气象站2005年逐时风速资料,拟合了风速的概率分布函数,分析表明:南京城、乡地面风速的概率分布均与3参数的韦伯分布吻合度很高,风速概率密度函数(PDF)曲线形状存在明显的城乡差别,城市风速PDF曲线更加陡峻,即风速分布更为集中;在0.75~3.75 m/s,城市风速PDF值明显高于周边乡村,而在3.75 m/s和0.75 m/s范围,城市风速概率密度值则低于乡村;城市下垫面的摩擦效应削弱风速而热力效应起增强风速作用,对风速的城乡差值序列的分析发现:多数时间城市风速是小于乡村风速的,但风速小于1.90 m/s条件下,城市风速会出现大于乡村的现象;总体上摩擦效应的作用远大于热力效应;城市效应使全年平均风速下降0.43 m/s。 相似文献
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为更好理解沿海区域近地面风速衰减规律及其内在机制并获取适用于业务观测风速数据的分析方法,通过引入内边界层厚度的发展机理,推导获得风速随离岸距离变化的数学解析拟合式。结合浙江省温州市境内一沿海区域6个自动气象站2014—2019年逐时风速观测数据应用该拟合式分析了风速随离岸距离的关系,结果表明不管是逐时风速还是逐日最大风速,其平均值均与离岸距离有着良好的负相关,并发现其衰减系数与风速有着密切关系。向岸流及离岸流的风速衰减特性均可以结合该拟合式用线性及幂数律拟合来体现,但后者可以更好地解释风速随离岸距离变化特征,并在较大风速(3~10 m/s)向岸流的背景条件下,获得合理可信的分析结果,说明该方法可以适用于近海岸区域风速观测数据的应用研究。 相似文献