Air monitoring network program in Saudi Arabia

The Kingdom of Saudi Arabia has initiated a program to install air quality network stations throughout the country in order to measure concentration of the ambient air pollutants. The site selection of these stations is an important objective to be accomplished and must be done based on scientific and rational work. To accomplish this objective, a modified version of atmospheric transport and dispersion model, known as air resources laboratories - atmospheric transport and dispersion (ARLATAD) model, is used to evaluate long range transport and diffusion of air pollutants from major pollution causing sources such as refineries, open-air burning of associated gases of oil fields and major industries.Hourly meteorological data for a period of three years (from 1977 to 1979) on wind speed, wind direction, pressure, and temperature from 20 synoptic stations in Saudi Arabia is processed and used as model input. In addition to these, meteorological data from three upper air stations is also processed in order to determine base and top of critical inversion heights.Various pollution causing sources are identified within the study area. Air trajectories are drawn with sources as the origins of the trajectories and the dispersion characteristics is studied with distance and time. Based on long term meteorological records, the adversely affected zones are statistically identified for potential station sites.     

Automated extraction and classification of thunderstorm and non-thunderstorm wind data for extreme-value analysis

Design wind loads are partly based on extreme value analyses of historical wind data, and limitations on the quantity and spatial resolution of wind data pose a significant challenge in such analyses. A promising source of recent wind speed and direction data is the automated surface observing system (ASOS), a network of about 1000 standardized US weather stations. To facilitate the use of ASOS data for structural engineering purposes, procedures and software are presented for (a) extraction of peak gust wind data and thunderstorm observations from archived ASOS reports, (b) classification of wind data as thunderstorm or non-thunderstorm to enable separate analyses, and (c) construction of data sets separated by specified minimum time intervals to ensure statistical independence. The procedures are illustrated using approximately 20-year datasets from three ASOS stations near New York City. It is shown that for these stations thunderstorm wind speeds dominate the extreme wind climate at long return periods. Also presented are estimates based on commingled data sets (i.e., sets containing, indiscriminately, both non-thunderstorm and thunderstorm wind speeds), which until now have been used almost exclusively for extreme wind speed estimates in the US. Analyses at additional stations will be needed to check whether these results are typical for locations with both thunderstorm and non-thunderstorm winds.     

A pilot study of the wind speed along the Rome–Naples HS/HC railway line.: Part 2—Probabilistic analyses and methodology assessment

The safety of railway operations under wind actions has recently become a topical matter due to the development of high-speed trains, which are very sensitive to crosswind conditions. For this reason, RFI (the Italian railway network) has entrusted the University of Genoa with a study of the wind hazard of the Rome–Naples High Speed (HS)/High Capacity (HC) railway line. A consistent part of such a study is focused on the probabilistic analysis of the wind speed and direction along that railway line, with the aim of developing a general procedure that can be applied to any railway line. This paper represents the logical prosecution of a companion paper where numerical simulations have been carried out of the wind fields along the line. These results are used together with a large amount of data measured by neighbouring meteorological stations in order to establish a probabilistic model of the wind speed and direction along the line. Such model provides a full representation of the wind climate and hazard of the railway line, and represents the basic step towards the development of a full risk analysis. Preliminary evaluations are also reported in order to assess the robustness and reliability of the methodology applied and the results obtained.     

An investigation into 50-year return period wind speed differences for Europe

50-year return period wind speeds have been calculated using yearly maxima from daily surface data and the Corine Land Use Land Cover database. By applying a single consistent methodology to wind speed data, coastal stations individually show more scatter, however, observed differences between Ireland, France and the United Kingdom decrease greatly when the north–east travelling extra-tropical cyclones are taken into account. Most inland stations show an appreciable degree of correlation in calculated wind speeds to nearby cross-border stations. The influence of outliers on 50-year return period wind speeds is investigated.     

Effects of inflow conditions on mountainous/urban wind environment simulation

Inflow conditions play a key role in the Computational Fluid Dynamics (CFD) simulation of wind environment. Taking the micro wind climate of Hong Kong Kowloon Bay costal town as a research object, two kinds of widely used inflow condition determination methods are adopted to test their performances. One is to fit the velocity profile into the empirical (logarithmic/exponential) law, hereafter referred to as the Fitted Empirical Profile (FEP) method. The other is to interpolate the outflow velocities and turbulence properties from a pre-simulation of the upstream region, hereafter referred to as the Interpolated Multiscale Profile (IMP) method. The GIS data of this mountainous/ urban area are digitalized and simplified into the CFD geometry model. Computational treatments for numerical algorithms, domain size, grid systems and boundary conditions are carefully configured according to the published CFD Best Practice Guidelines (BPGs). By validating with one year of real scale wind measurement data from two meteorological stations, it is found that these two inflow conditions lead to considerably different results. Having less consideration for the blockage effects of terrain/buildings, the FEP method tends to predict higher wind speed. As more thermal effects are removed by increasing wind speed thresholds, the results of IMP method demonstrate an incremental agreement with the measurement data. Finally, the validated simulation results are applied to the spatial representativeness assessment of two meteorological stations. Both the point-to-surface consistency indicator and point-centered semivariance are employed. The results show that the meteorological stations show a good representation within a range of 400 m.     

佛山地区考虑风向影响的基本风速统计分析

基于南海气象站的气象资料,首先对三种极值分布的参数进行估计,并对三种极值分布进行线性相关性检验,得出南海气象站风速极值分布更接近Weibull分布;其次对Weibull分布参数的谐波函数拟合曲线,得到任意风向角下的分布参数;最后分析各风向角下的基本风速;所得到的结果可为建筑结构抗风设计提供参考.     

基于泊松-耿贝尔法的最大风速估算

由于每年发生台风的次数、移动路径及强度都是随机的,构成了某种离散性分布,常规采用的极值Ⅰ型分布的耿贝尔法是收集每年的最大风速,这种方法无法收集到每一次台风影响的最大风速.文中采用泊松-耿贝尔联合极值风速计算方法,计算了重现期为5、10、20、50年的最大风速与基本风压.结果表明泊松-耿贝尔联合极值风速计算方法偏差比极值...     

Model simulation of meteorology and air quality during the summer PUMA intensive measurement campaign in the UK West Midlands conurbation

The Regional Atmospheric Modeling System (RAMS) and Urban Airshed Model (UAM IV) have been implemented for prediction of air pollutant concentrations within the West Midlands conurbation of the United Kingdom. The modelling results for wind speed, direction and temperature are in reasonable agreement with observations for two stations, one in a rural area and the other in an urban area. Predictions of surface temperature are generally good for both stations, but the results suggest that the quality of temperature prediction is sensitive to whether cloud cover is reproduced reliably by the model. Wind direction is captured very well by the model, while wind speed is generally overestimated. The air pollution climate of the UK West Midlands is very different to those for which the UAM model was primarily developed, and the methods used to overcome these limitations are described. The model shows a tendency towards under-prediction of primary pollutant (NOx and CO) concentrations, but with suitable attention to boundary conditions and vertical profiles gives fairly good predictions of ozone concentrations. Hourly updating of chemical concentration boundary conditions yields the best results, with input of vertical profiles desirable. The model seriously underpredicts NO2/NO ratios within the urban area and this appears to relate to inadequate production of peroxy radicals. Overall, the chemical reactivity predicted by the model appears to fall well below that occurring in the atmosphere.     

A driving rain exposure index for Norway

Determination of driving rain exposure typically requires hourly values of rainfall and mean directional wind speed. Weather data at most observing stations in Norway are not recorded as hourly values and are therefore not amenable to this type of analysis. We present an alternative method for assessing driving rain exposures based on multi-year records of synoptic observations of present weather, wind speed and direction. Distributions of numbers of rain observations and wind speeds versus wind direction combined with average annual rainfall totals yield quantitative information about driving rain exposures at stations. Results from four weather stations in Norway are presented and discussed, using weather data from the period 1974–2003.     

Wind energy potential,development and current trends in India: a review

The demand for electricity is increasing day by day in the world. In a developing country such as India, the electricity demand is increasing at a terrifying rate as compared to the meagre supply. At present, the Indian power industry is mostly based on fossil fuel. Nowadays, wind energy has emerged as a renewable energy source which has a huge power generation capacity. India is one of the leading producers of wind energy but has the potential to generate even more energy through it. This paper presents a review of wind energy resources, its potential, development and current trends in India. A wind turbine can be easily set up as it takes less space as compared to other power stations and can be easily located at places such as deserts, remote areas, offshore, etc.     

Application of the James—Stein estimator to extreme wind speeds

Use is made of a recent (1955) mathematical finding that has overturned 150 years of statistical theory going back to Gauss. A heuristic study using a simple Monte Carlo model is used to demonstrate the meaning and validity of this finding as it well be applied in this paper. Application is then made to wind speed data typical of those found in many wind engineering design codes, with specific examples of Australian and United States data, and considerably different 50-year return period wind speeds are thereby predicted for stations not close to the overall average. It is concluded that at the least it is imprudent to present wind design information in terms of speeds for various return periods for each particular recording station, and that a simple association into a number of speed groups is as much as should be attempted.     

Assessing wind energy potential for electricity generation using WECS in eight selected stations of Ethiopia

Wind utilisation for effective electricity generation has dated since last two decades by means of the modern wind turbines and has proved as a mature, reliable and efficient technology. This paper integrates the wind characteristics and performance of selected wind energy conversion systems (WECSs) from eight selected stations within Tigray region in Ethiopia. The wind speed data were collected over a period between 2002 and 2014. Based on the Paci?c Northwest Laboratory (PNL) classification, all the selected stations fall into Class 1. Therefore, these stations may be advised for small-scale power applications. Furthermore, the highest annual energy output achieved was 3902.31?MWh using VESTAS V110 – 2.0 at Mekele.     

Wind quantile estimation using a pooled frequency analysis approach

Extreme wind quantiles are needed to calculate design values of wind load-effect on structures. These quantiles are estimated by conducting frequency analysis of the available wind data. Usually, at the site of interest either wind speed data are not available or are of very short record length. Wind quantile estimates have large standard errors if estimated from limited data. In the present work, the concept of focused pooling of information for the site of interest is proposed. The use of this approach has been demonstrated by developing wind quantile estimates for 26 wind stations of Ontario, Canada.     

Extreme wind climate of the United Kingdom

The results of improved extreme value analyses of wind data from 50 meteorological stations in the United Kingdom, together with comparisons with previous analyses and the implications for structural design practice are discussed. In contrast to earlier methods, the present approach uses a dynamic pressure model and greatly increased amounts of data. It enables the seasonal and directional characteristics of extreme winds to be assessed reliably. The directional results are used to demonstrate the effectiveness of contemporary procedures to correct for terrain roughness and topography.     

Investigating the reliability of RC beams of tall buildings designed based on the new ACI 318‐05/ASCE 7‐05

The level of safety achievable in reinforced concrete (RC) beams designed based on the new ACI 318‐05/ASCE 7‐05 is investigated in this study. The study makes use of the more recent statistical data on flexure and shear provided by Szerszen and Nowak. Due to the importance of using real ratios of lateral/gravity loads in any such reliability analysis, a set of RC buildings was chosen, loaded and designed and the actual nominal wind‐to‐dead load ratios were derived. Using these and the statistical data mentioned above, reliability indices for moment and shear were calculated. The resulting reliability indices for moment and shear are then presented in comparison. In addition, the reliability index variations along the beam at the controlling stations are compared to each other. The results of the study indicate that reliability indices at the controlling stations obtained for different limit states are not consistent for low values of nominal wind‐to‐dead load ratios, but converge consistently for high ratios. It seems that the use of older shear strength factors provides a reliable safety margin and that the use of the more recent statistical data for material combined with the older shear strength factors leads to more consistency. Copyright © 2010 John Wiley & Sons, Ltd.     

Atmospheric pollution potentials over India†

A study of atmospheric pollution potentials based on morning mixing heights, afternoon mixing heights, horizontal wind speeds, is made for all the radiosonde stations over India. An index called “Ventilation factor” is evolved for different India stations for all seasons, to discuss the air pollution potentialities. The above parameters are examined in the light of future possible industrialization and urbanization. A modified method has been evolved to compute morning mixing heights particularly applicable to India stations after examining critically Holzworth's method.     

The methodology for aerodynamic study on a small domestic wind turbine with scoop

The aim of this study is to investigate the possibility of improving wind energy capture, under low wind speed conditions, in a built-up area, and the design of a small wind generator for domestic use in such areas. This paper reports the first part of this study: the development of the methodology using physical tests conducted in a boundary layer wind tunnel and computer modelling using commercial computational fluid dynamics (CFD) code. The activities reported in this paper are optimisation of a scoop design and validation of the CFD model. The final design of scoop boosts the airflow speed by a factor of 1.5 times equivalent to an increase in power output of 2.2 times with the same swept area. Wind tunnel tests show that the scoop increases the output power of the wind turbine. The results also indicate that, by using a scoop, energy capture can be improved at lower wind speeds. The experimentally determined power curves of the wind generator located in the scoop are in good agreement with those predicted by the CFD model. This suggests that first the developed computer model was robust and could be used later for design purposes. Second the methodology developed here could be validated in a future study for a new rotor blade system to function well within the scoop. The power generation of such a new wind turbine is expected to be increased, particularly at locations where average wind speed is lower and more turbulent. The further study will be reported elsewhere.     

Design for wind comfort in The Netherlands: Procedures,criteria and open research issues

A code for the assessment of wind comfort and wind danger in the built environment in the Netherlands is presented. The code is not another legal building requirement, but a helping hand to include wind comfort in a building programme. It regulates technical procedures and some quality control. A decision scheme indicates which building plans need professional assessment by wind engineers.Local wind speed data are predicted from wind tunnel or CFD simulations. Statistics of a reference wind speed at the building location is needed to calculate the probability that a threshold wind speed is exceeded. The code prescribes a method which is offered as a software package to calculate the statistics of the reference wind speed at a height of 60 m. It includes the most up-to-date data from meteorological stations in the Netherlands.The probability that the pedestrian wind speed exceeds a threshold value of 5 m/s is a measure for wind comfort. Larger probability means less comfort. Therefore, five grades of wind comfort A–E are defined as function of this probability. In addition, for three different activities of the public (traversing, strolling and sitting) these grades of wind comfort are assessed in terms of a poor, moderate or good local wind climate.