Simulation of the probable maximum flood in the area of the Leningrad Nuclear Power Plant with account of wind waves

At the designing of nuclear power facilities at the coastal sites the risk of their flooding caused by the combinations of adverse hydrometeorological events should be assessed with the probability of exceedance to 0.01%. According to the IAEA recommendations, the combination of statistical and deterministic methods was used to calculate the flood level of such rare occurrence. The level of flooding caused by the storm surge and reiated wind waves were computed with the probability of 0.01% for the coastal part of the Koporye Bay of the Gulf of Finland in the area of the Leningrad Nuclear Power Plant 2 (LNPP 2) construction; the results are presented. The calculations are based on the CARDINAL and SWAN software and four nested numerical models (for the Baltic Sea, the eastern part of the Gulf of Finland, the Koporye Bay, and a part of the bay in the area of LNPP). The decrease in sea-surface drag coefficient at hurricane winds is taken into account.     

Hydrodynamic modeling of floods in Saint Petersburg considering the operating dam

The Baltic Sea level is computed from the BALT-P three-dimensional hydrodynamic model at the grid with the horizontal resolution of 2 nautical miles, and the computation for the top of the Gulf of Finland is provided at the grid with the spatial resolution of 90 m. The sea motion is induced by the air pressure gradients and wind stress values from the HIRLAM model forecast specified on the sea surface. The sea level is calculated for three floods in Saint Petersburg with account that each of eight spillways of the dam closed and opened not instantly but during the prescribed period of time. It is revealed that the BALT-P model simulates the sea level well during three floods in Saint Petersburg considering the operating dam. The model can be used for the sea level forecasting in Saint Petersburg based on the HIRLAM atmospheric model data with the lead time of 60 hours.     

湍流大气中水平风速模涨落的相关

推导出湍流度不大时,水平风速模涨落的相关,方差等量与分量风速涨落相应量联系的近似式。計算表明,在大气湍流微結构研究通常遇到的湍流度下,模量的相关与順风分量相关差不多. 說明了小尺度大气湍流中,风速模涨落的空間相关也可以近似地以时間相关来代替. 討論了推导时引入的附加条件在大气中的合理性。     

水雾输送扩散的数值研究

本文利用边界层能量闭合模式,对金沙江上某地水电站泄洪产生的水雾的输送和扩散过程进行了模拟,分析了对下风方向湿度场的影响和水雾存在范围与主要气象条件的关系。模拟表明：水雾分布范围随水雾源强的增大而增大,并且随风速增加而增加,与背景相对湿度关系不大;相对湿度受影响的范围与背景相对湿度几乎无关,但与水雾的源强,风速有关;在较高背景相对湿度的河谷地带,影响水雾分布范围的最主要因素是水雾源强和风速。     

平台障碍物对海气通量观测影响的数值分析

基于计算流体动力学模型（CFD）模拟了背景风风速为2 m·s-1、4 m·s-1、6 m·s-1下通量观测平台周围的风场分布,确定了不同风速下平台障碍物对观测影响最小的风向范围。发现风速不同,平台对背景风的影响范围不同,风速越大,平台对背景风的影响越大。运用涡动相关法计算不同风向条件下的湍流通量,定量分析由于平台干扰对海气通量计算的影响,发现选取迎风条件下的数据计算得到的海气通量会比实际偏低。     

Vaisala WAV15风向传感器 WAA15风速传感器介绍及维修

广州白云国际机场目前使用的AWOS2000自动观测系统的测风系统是由芬兰Vaisala公司的WAV15风向传感器、WAA15风速传感器和其它相关设备(数据采集包DCP和计算机处理部分)组成的.通过对风系统故障检修的实践,我们找出了用国产IC替换原器件的成功经验,大大缩短维修周期,有效提高设备正常率和完好率.     

CAWS型自动站与人工观测风速记录的对比分析

利用平凉气象观测站2003年1~12月人工站和自动站平行观测的风速、风向资料,统计比较了2003年1~12月人工站与自动站风速观测值和极值,结果表明:受观测仪器系统偏差和观测取值时间差异的影响,人工站比自动站的日平均风速偏小0.4 m/s。风向完全相符的接近40%,2个以上方位的不相符率4%。     

On the problem of the Neva river flood waves identification

Based on the analysis of the measurements of hydrometeorological characteristics, the identification is corroborated of the Neva River flood waves as the baroclinic topographic waves. It is demonstrated that during the formation and maximum development of the most significant sea level rises in the Neva Bay, the stratification in the Gulf of Finland still remains pronounced despite the storm conditions. The baroclinic nature of the flood wave is indicated by the significant changes in the dispersion of currents with depth with their direction changing to the reverse one as it occurs in the first baroclinic mode wave. Directions of major axes of the standard deviation ellipses are oriented not along the isobaths as it should be in case of long gravity waves (being the longitudinal ones) but are extended across the bottom topography contours that is typical of gradient-vorticity waves assigned to the class of horizontal transverse waves.     

Nocturnal boundary layer height prediction from surface routine meteorological data

Summary A number of well known diagnostic equations for the determination of the height,h, of the nocturnal boundary layer. with minimum data requirements of at most surface wind speed, air temperature and total cloud cover, have been tested as to their effectiveness. The computed values have been compared with direct estimation ofh, from temperature or wind profiles of rawinsonde ascents available at 00Z (02h LST). The comparison between computed and observed values shows that best agreement is found when the nocturnal boundary layer height is determined through wind profiles. The ratio of the computed to the observed values reveals a strong dependence on stability, resulting in overestimation by the models for very low stability and underestimation for strong stability. The simple expressions involving the wind speed rather than other stability parameters resulted in a better overall fit to the observed values. A simple prognostic model is shown to provide the best estimates of the NBL height compared to both wind and temperature profile definition.With 5 Figures     

Mesoscale Wind Field Modifications over the Baltic Sea

For two consecutive days during spring 1997, the windfield over the Baltic Sea has been studied. Thestrength of the geostrophic wind speed is the majordifference in synoptic conditions between these twodays. During both days, the mesoscale wind field overmost of the Baltic Sea is quite heterogeneous; themodifications primarily being caused by the land-seacontrasts. On the day with the weaker wind speed,sea-breeze circulations develop. As a consequence, thewind direction at lower levels is more or lessopposite to the geostrophic over large areas of theBaltic Sea and the surface wind speed decreases withoffshore distance. Wind speed maxima caused by the seabreezes are found along the east coasts in the studiedarea. For the other day, the slow growth of a stableinternal boundary layer over the sea also gives asurface wind speed decrease with offshore distancefrom the coast.     

三层模式中风场对背风波的影响

为了研究风场对背风波的影响,针对边界层附近为弱稳定层结的背风波,建立了一个三维三层的理论模型和线性计算模式,分析了各层中风速和风向的变化对背风波特征的影响,揭示了气流过孤立山脉产生背风波的有利风场条件。结果表明：背风波的波长、振幅等特征对各层风速和风向的变化具有相当的敏感性,波长随着低、高层风速的增大而增大,随着中层风速的增大先减小后增大;振幅随着低、中层风速的增大先增大后减小,随着高层风速的增大而增大。此外,风速和上下层风向切变的增大均使背风波的形态逐渐由横波型转为辐散型,但是上下层风向的切变对背风波形态的影响比风速更为显著。     

Statistical and spectral analysis of the wind regime in the area of Catalonia

Summary This work presents a statistical study of the wind power potential of three stations in the Catalonia area (Spain) over the 1973–1982 period. These stations correspond to three airports (Barcelona, Palma de Mallorca and Girona), which obviously do not present a high wind power potential and are not the suitable locations for wind power utilization, but which have been chosen for the long record of data stored (10 years). The aim of this work is to provide a model of wind potential in terms of the speed and wind direction, which may be applied to other sites. The wind speed has been modelled by a Weibull distribution function and the wind direction by a normal two-dimensional function. A spectral analysis of both variables has also been carried out. The present study provides an evaluation of the local wind power in the geographic area of Catalonia.With 10 Figures     

一种考虑海拔高度的风速测量相关推测法

测量相关推测法 (measure-correlate-predict,简称MCP方法) 广泛应用于风能评估,它基于风场空间相关原理,利用参照站和目标站同步短期风记录来推测目标站点长期风速和潜在风能大小。但以往任何一种MCP方法都只能推测与参照站在同一海拔高度上目标站的风速,而对于较高或较低处目标站风速的推测会出现较大误差,具有局限性。该文选取内蒙古锡林郭勒草原地区两座风能测风塔2009年5月—2010年4月的6层高度数据,拟合出Weibull双参数分布随高度变化的公式,从而得到高低空风的关系。并通过Weibull双参数分布法,在方差比MCP方法的基础上建立起一种修正的MCP方法,它修正了方差比MCP方法由于海拔高度不同而引起的误差。最后选取了4种检验因子 (相关系数、平均风速、卡方拟合优度、年平均发电量) 对方差比MCP方法和修正的MCP方法分别进行考察,并进行对比分析。结果表明:修正的MCP方法推测结果更接近于实测值,4种检验因子检验结果较方差比MCP方法更优,能够运用到难于测量地区的风能评估。     

Non-Linear Numerical Model Predictions of Flow Over an Isolated Hill of Moderate Slope

Non-linear model simulations of atmospheric boundary-layer flow over the hill called Blashaval have been compared with observations and linear model predictions. Previous studies have shown that linear models can give good predictions of wind speed at the summit and on the upwind slopes of Blashaval. The non-linear model provided wind speed predictions of similar accuracy when compared with the mean observed values at these locations.The published experimental data showed that on the lee-slope the wind speeds at 8m were reduced to approximately 10% of their upstream value at the same height. This was associated with an 180° change in wind direction compared with the upstream flow, suggesting that flow separation had occurred. The non-linear model predictions of lee-slope wind speed, when used with high-resolution topography data, were significantly better than linear model predictions. However, the non-linear model predicted lee-slope wind speeds that were still stronger than observed. The non-linear model simulated flow separation more readily with a 1 1/2-order turbulence closure than with a first-order, mixing-length closure. The configuration of the non-linear model that gave best agreement with observations predicted an 8m lee-slope wind speed that was around 50% of the upstream value.     

The influence of momentum advection on the Baltic Sea dynamics

Contribution of momentum advection to the formation of the low frequency fields of the Baltic Sea levels and currents is estimated using numerical experiments with a hydrodynamic model and statistical analysis of the experimental results. It is found that momentum advection has a significant influence on the formation of the mean level and its seasonal and synoptic variability in Neva Bay of the Gulf of Finland. The results show that nonlinear effects associated with advective accelerations can essentially contribute to the Neva River flood formation.     

泰山顶部近地层风的方差与谱分析

风在速度与方向上的不稳定性可引发结构振动并可导致损坏。山顶风较少受局地作用影响, 流场较稳定，作为典型风况对山顶风湍流脉动情形进行的观测和分析，对于研究建筑结构风载振动情形有着重要意义。在不同风况下对泰山气象站近地层风的风速和风向进行了同时、逐秒测记，所得样本经检验符合正态分布。计算表明，风向样本方差显著大于风速样本方差。绘制了各风速、风向样本自、互谱密度曲线图。谱图显示诸样本具有红噪声序列特征，不同样本自、互谱密度曲线具有相近形状，而以风速自谱曲线吻合程度最好，谱密度曲线在周期为4秒及2秒处有峰值。此后的研究应结合记录仪器的改进增加采样频率，对周期为2秒以下谱曲线作进一步分析。     

The modelled wind climatology of the Adriatic Sea

Summary A 29 year wind hindcast has been used to investigate the climatology of the Adriatic Sea. First we characterize the basin in terms of its monthly and annual mean distributions. Then we consider the evolution in time of the average conditions and look for the possible existence of trends. The analysis of the daily mean values over the whole period shows the existence of preferential periods of the year for atmospheric activity. Different areas of the basin have been characterized with respect to combined wind speed and direction and to the frequency of the dominant storms. Finally, we discuss the accuracy of the results.With 18 Figures     

基于WRF模式的风电场短期风速集成预报方法研究

风能始源于大气的运动,具有很大的随机性和间歇性。风速预测是风电场风功率预测的基础,其准确性具有重要的意义。对于复杂地形条件下,风速的预报一直是各国研究的难点和重点。为了提高风电场短期风速预报的准确性,本研究采用多种边界层参数化方案来集成预报风速,将各单一边界层参数化方案预报的风速及相应的实测风速数据,应用随机森林算法建立集成预报模型,对风电场的短期风速进行集成预报研究。试验结果表明,采用集成预报风速方法,预报的风速误差相比于单一边界层参数化方案预报的风速误差明显减小,对研究区域的风速、风向等气象要素有着较好的模拟效果,能够有效提高风速预报的准确率。     

Wind structure near a city centre

Wind speed and temperature profiles to a height of 8 m were recorded for 30-, 60-, and 90-min averaging times over a striated snow surface at the geographic South Pole during the austral winter of 1975. A gradient Richardson number was calculated for each averaging time to determine conditions of neutral stability under which the logarithmic wind law would hold. A log-linear regression technique was used to determine values of aerodynamic roughness height (Z ₀) for those profile averages recorded in conditions of neutral stability. A plot of Z ₀ as a function of average wind direction revealed a variation in Z ₀ of almost three orders of magnitude, from 0.01 to 7 cm, over 120 deg of wind direction. A simple model is presented to justify the fact that aerodynamic roughness is a function of wind direction and erosion history.