苏通大桥桥位江面风速的数值试验

用WRF中尺度模式对苏通大桥桥位江面的风速进行了数值模拟。在修改了模式自带的静态地形数据后模拟效果较修改前有所改善。并发现在对天气系统有较准确模拟的情况下模式对桥位江面最大风速的模拟也较为精确,反之结果相差较多。挑选了其中两个个例并使用修改过静态地形数据的模式分别对地形和一些物理方案作敏感性试验,发现各种因素对模拟结果都有着不同程度的影响,起决定性作用的是水陆分布;在没有强对流天气系统的情况下各种微物理参数化方案对模拟结果均不产生明显影响;模拟时需加入长短波辐射参数化和边界层参数化方案,并且其中YSU边界层参数化方案的模拟结果最为理想。在缺乏江面风观测数据的时段里模式对江面风速的模拟结果具有一定的参考价值。     

Turbulence spectra of CO2, water vapor,temperature and wind velocity fluctuations over a crop surface

A prototype rapid-response CO₂ sensor was used in conjunction with a Lyman-alpha hygrometer, fine-wire thermocouples and a three-dimensional drag anemometer to measure CO₂, humidity, temperature and wind velocity fluctuations. Measurements were made over a soybean crop grown on relatively flat terrain near Mead, Nebraska.Temperature, humidity and CO₂ spectra measured under near neutral conditions were most similar in shape while longitudinal velocity (U) spectra appeared to be somewhat broader. Peaks occurred around f = 0.02 to 0.06 (where f is the non-dimensional frequency) in all spectra except for vertical velocity which had a peak near f = 0.5. As thermal stability changed from neutral to stable, spectra exhibited lower peaks, were narrower in shape and were shifted towards higher frequencies. Opposite behavior was observed with increasing instability.Cospectra for momentum, heat, water vapor and CO₂ measured during neutral conditions had similar peak frequencies (near f = 0.15). Among the cospectra studied, CO₂ and water vapor cospectra had the greatest similarity in shape.Published as Paper No. 7481, Journal Series, Nebraska Agricultural Experiment Station. The work reported here was conducted under Nebraska Agricultural Experiment Station Project 27-003 and Regional Research Project 11-33.Post-doctoral Research Associate and Professor, respectively, Center for Agricultural Meteorology and Climatology, Institute of Agriculture and Natural Resources, University of Nebraska, Lincoln, NE 68583-0728.     

环渤海区域再分析资料地面风速场的适用性对比分析

利用环渤海区域的气象站资料和NCEP/NCAR、NCEP/DOE、CFSR、ERA Interim、JRA-55共5种再分析资料,讨论了再分析资料近地面10 m平均风速场在环渤海区域的适用性问题。结果表明：JRA资料与观测站的相关系数最大,ERA资料与23站均方根误差的平均最小;再分析资料与气象站观测资料的相关系数在山东半岛和辽东半岛高于其他地区、冬半年大于夏半年。环渤海区域地面10 m平均风速场JRA和ERA两套资料的适用性较好。由于ERA-Interim的水平分辨率更高,所以在强风过程分析中确定使用ERA Interim再分析资料。     

A model for computing small-scale wind variations over a water surface

Based on the primitive equations, a one-level model is described for computing surface winds under the meso-scale influences of orography, friction and heating. The effects of atmospheric stability and land-water contrasts are examined in detail. Results of testing the model with data collected during the International Field Year for the Great Lakes (IFYGL) in 1972 are given. The model is able to simulate land and lake breezes as well as meso-scale effects due to gradients in surface water temperature. Compared to simple methods of computing surface winds, use of the model reduces the vector error in estimates of surface winds by about 1.25 m s^–1 on the average.     

Wind-wave generation and the wind velocity structure in the air above a wavy water surface

Research results are presented, under natural and laboratory conditions, concerning the process of wind-wave generation. The complementary problem, the effect of waves on the structure of the wind field above them, is also studied.     

Friction velocity scaling in wind wave generation

This note is devoted to the problem of the appropriate scaling of parameters relevant for sea waves, such as wave height, peak frequency, duration, and fetch. In the past, the growth of sea waves has often been analysed in terms of the wind velocity at a fixed height, despite the fact that many authors have stressed the importance of scaling with the friction velocity. This problem would be immaterial if the ratio between the friction velocity and the wind speed at a fixed height were a constant. There is, however, ample evidence that this ratio increases with wind speed (Smith and Banke, 1975; Smith, 1980), in agreement with dimensional considerations by Charnock (1955) on the friction height. As a result, the scaling problem is an important one. In this note we conjecture that the correct procedure is to scale wave parameters with friction velocity, and we discuss experimental evidence for the correctness of this conjecture. Comparing two independent datasets (JONSWAP and KNMI), we find some evidence supporting our ideas. Further confirmation remains desirable, however, and suggestions are made as to how this might be obtained.     

Development of observation-based parameterizations of standard deviations of wind velocity fluctuations over an Indian region

Theoretical and Applied Climatology - The present study utilizes the turbulence observations over an Indian region, Ranchi, to study the diurnal and seasonal characteristics of mean and turbulent...     

风电场风速数值预报的动态修订方法的探讨

针对风电场风功率预测所需的定点、逐时风速预报,对利用中央气象台发布的MM5格点输出的数值预报风速插值到福建沿海某个风电场测风塔高度的预报结果进行误差分析,发现由于海陆交界的特殊下垫面等原因,存在一定的系统误差;根据误差的后延相关性和测风塔实时发回的气象资料,探讨了利用前期误差观测值和测风塔湍流指标对MM5数值预报风速进行动态修订的方法,建立了订正值方程,结果表明,订正后的预报风速平均绝对误差降低31%~54%,有效提高了预报精度。     

贵州福泉历史风向风速统计分析

统计分析了贵州福泉自建气象站以来累积的47a风向风速资料,得出福泉47a的风向风速分布及变化特征,风速年、月、日、时的时间分布及最多风向等。     

On the measurement of second moments of turbulent wind velocity with a single Doppler radar over non-homogeneous terrain

The measurement of turbulent wind quantities with a single Doppler radar requires a horizontal homogeneity assumption. When the terrain is not horizontally homogeneous, then the measurement of the various moments is contaminated by the gradients of these moments. However, by scanning the radar at three different elevation angles, the contamination from these gradients can be removed from the second-moment quantities of interest.     

Kolmogorov constants for CO2, wind velocity,air temperature,and humidity fluctuations over a crop surface

The Kolmogorov constants for CO₂, wind velocity, air temperature, and humidity fluctuations were evaluated from measurements made over soybean and grain sorghum fields and found to be 0.78 ± 0.11, 0.49 ± 0.08, 0.70 ± 0.15, and 0.99 ± 0.16, respectively. These results are consistent with recent observations reported in the literature.Published as Paper No. 7255, Journal Series, Nebraska Agricultural Experiment Station. The work reported here was conducted under Regional Research Project 11-33 and Nebraska Agricultural Experiment Station Project 27-003.Associate Professor and Post Doctoral Research Associate, respectively, Center for Agricultural Meteorology and Climatology, Institute of Agriculture and Natural Resources, University of Nebraska, Lincoln, NE, U.S.A., 68583-0728.     

Two-point velocity statistics over Lake Ontario

Cross-spectra between wind speeds on several masts in Lake Ontario have been analyzed. As previously predicted, coherence over water (small intensity of turbulence) between wind speeds measured on masts lined up with the wind appears to be larger than over land, and increases with decreasing Richardson numbers. As a result, in cold air over warm water, wind speed fluctuations are well predictable from upstream measurements. For large angles between the anemometer line and wind, the difference between coherence over land and water disappears. Furthermore, there is no significant difference in vertical coherence between water and land. When the wind is parallel to the anemometer line, small eddies travel, in agreement with Taylor's hypothesis, with the local mean wind speed. Large eddies travel significantly faster. Vertical phase delay increases with increasing Richardson number.     

Variation in road surface temperature due to topography and wind

Summary The present study involves a discussion of nocturnal temperature variation due to topography and prevailing wind speed. It is part of the ongoing project Applied climatology for increased traffic safety and road maintenance, which aims at a development of a local climatological model applicable to winter road conditions. The temperature recordings which are used are from sensors in the Swedish Road Weather Information System in the county of Skaraborg.During clear and calm nights, local air temperature differences have been related to different topographical environments. The main factors resulting in large temperature differences are the effect of wind shelter, stagnation or production of cold air, and of cold air advection.Variation in air temperatures during clear and windy nights has also been studied. At wind speeds higher than 4–5 m/s, the temperature variation is low. With decreasing wind speed the variation in temperature increases, but only for sensor sites which have some wind shelter by topography or vegetation.The air temperature variation which develops during clear nights affects the road surface temperature. In this paper, the connection between road surface temperature differences and air temperature variation is discussed. A linear relationship between the two variables exists.With 5 Figures     

Height dependence of diurnal variations of wind velocity and water temperature near the air-sea interface of the tropical Atlantic

From measurements during the Atlantic Trade Wind Experiment (ATEX) 1969, amplitudes and phases of the diurnal harmonic water-temperature variation between the sea surface and 50-m depth and of the semi-diurnal wind variation between 1 and 8 m were obtained. If the vertical diffusion of heat in the ocean is thought to be constant, a coefficient of K= 320 cm² s^–1 in the equation of diffusion fits best the observed data in the mixed layer. However, the measurements point to a decrease of K with depth.The height variation of the semi-diurnal zonal wind wave is caused by the influence of eddy viscosity. Our data are well fitted by results of the equation of diffusion, using the assumption of Lettau (1974) that the transfer coefficient of vertical transport of momentum is not only a function of height but also depends on time because of the semi-diurnal variation of surface stress.     

The turbulent wind flow over an embankment

Under neutral conditions and with low winds, profiles of mean and turbulent wind components have been measured at various points across an embankment with aspect ratio 0.3. These measurements have been compared with and related to those of undisturbed flow in a horizontal homogeneous area on the windward side. The speed-up ratio, the turbulent and mean kinetic energy and the turbulent shear stress are examined. It is found that the flow stagnates on the windward side, accelerates above the crest, and separates behind the crest. The results show a remarkable dependence on the angle of attack. With an angle smaller than 90 °, the influence of the embankment on the mean wind field is reduced but is increased on the turbulent part, as lateral gustiness components are amplified. With the incoming flow normal to the embankment, maximum turbulence is found on the top of the ridge near the surface but at greater heights farther downwind. The same is true for the shear stress, but only for oblique flow, whereas for normal flow a minimum is found above the crest and a maximum on the windward side. Therefore, with varying angle of attack the embankment acts in different ways on mean wind, turbulent kinetic energy, and turbulent stress. Although the winds were low, all effects are clearly evident in the data.     

石家庄市风环境容量变化特征及区划研究

利用气象观测、高分辨率城市地理信息、卫星遥感反演及ERA-Interim再分析资料,基于水平风速、混合层高度及地表粗糙度长度指标,利用等权重加权综合评价法和几何间隔分级法,开展了石家庄市风环境容量指标和区划研究,得到风环境容量指数分级阈值和空间分布.结果表明,石家庄市水平风速和大气混合层高度均由西部山区向东南部平原逐渐降低,在西南部山区存在一个高值区,在东南部平原存在一个低值区,且具有明显的季节和日变化特征;石家庄市区和西部山区地表粗糙度长度较大,平原地区较小;风环境容量指标分为低值区、次低值区、中等区、次高值区和高值区5个等级,在空间上石家庄市区及平原地区级别较低,西部和北部山区级别较高,其中石家庄市区、正定东南部、栾城东部、藁城大部分地区及无极西部是风环境容量最低区域,赞皇、高邑、赵县西南部、元氏西部、南部及井陉西南部为最高区域.     

风向风速传感器的原理及其检测

介绍对风传感器的维护、维修及检测的方法和经验。     

行星边界层中多极值风速廓线的研究

本文利用325米气象塔及声雷达探测资料分析了夜间平稳天气条件下行星边界层中风速出现多极值的现象。分析指出,多极值风速与边界层中多层逆温有密切的联系,当温度场出现多层逆温并维持一定的强度和时间后,便相应地出现了多层风速极大,风速极大值出现的高度在逆温顶附近或稍高。 文内还用一维非定常模式模拟了多极值风速廓线的形成。     

风向风速传感器的原理及其检测

介绍对风传感器的维护、维修及检测的方法和经验.