共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
K. H. Papadopoulos N. C. Stefantos U. S. Paulsen E. Morfiadakis 《Boundary-Layer Meteorology》2001,101(1):77-107
Four commercial and one research cup anemometers were comparatively tested in a complex terrain site to quantify the effects of turbulence and flow inclination on the wind speed measurements. The difference of the mean windspeed reading between the anemometers was as much as 2% for wind directions where the mean flow was horizontal. This difference was large enough to be attributed to the well-known overspeeding effect related to the differing distance constant (ranging from 1.7 to 5 m) of the cup anemometers. The application of a theoretical model of the cup-anemometer behaviour in athree-dimensional turbulent wind field proved successful in explaining theobserved differences.Additional measurements were taken with the anemometers tilted at known angles into and out of the incident wind flow. Thus, a field-derived angular response curve is constructed for each anemometer and the deviations from publishedwind-tunnel results are discussed.The uncertainties of, or false assumptions about, the angular response characteristics of the anemometers contribute the largest amount inthe observed errors of mean wind speed even for a horizontal mean flow. The angular response curves are finally used to correct the 10-min mean windspeed. The necessary information for the correction is the turbulent intensity (preferably in the vertical direction) and the mean flow inclination.For demanding applications, the angular response parameters of cup anemometers should be taken into account. The incorporation of the angular response parameters in a correction scheme would be most robustly applied if their variation with inclination and wind speed was smooth. 相似文献
3.
Errors in turbulence measurements with a sonic anemometer 总被引:1,自引:0,他引:1
Errors in surface-layer wind data obtained by sonic anemometers are estimated as a function of relative wind direction using a comparison between two identical anemometers. The maximum errors in mean windspeed and the standard deviations of the horizontal wind components are found to be between 10 and 20%. Agreement between the size of the measured errors and those calculated from wind-tunnel data is fair.In addition, vertical velocity data are analysed to show the presence of flow distortion induced by the asymmetry in the sonic anemometer probe and the mounting of the probe on the top of a mast. 相似文献
4.
S. E. Hobbs 《Boundary-Layer Meteorology》1994,68(3):259-273
The results of calibrations of the airspeed measurement, distance constant and cosine response for a sensitive propellor (vane) anemometer are described. A triad of these anemometers may be used to measure wind velocity, and the estimated uncertainty in this measurement is evaluated for a typical triad and a range of wind directions.The propellor anemometers tested provide sensitivity similar to that of sonic anemometers for research, but at much lower cost (although for a narrower range of wind conditions). Large arrays of the anemometers allow the spatial and temporal structure of wind turbulence to be measured directly. The anemometers have been used for several years, and are robust enough for micrometeorological research. 相似文献
5.
A. D. Surridge 《Boundary-Layer Meteorology》1982,24(4):421-428
The measurement of atmospheric winds using a cup anemometer to measure speed and a wind vane to measure direction, recording the data on paper charts is commonplace. Standard Meteorological Service criteria stipulate that the wind charts so recorded are read (averaged over one hour) by taking the dominant wind direction over an hour and the wind run then gives the speed over that hour. However, fluctuations of wind direction can lead to erroneous results. A vector average wind obtained using two orthogonally mounted propeller anemometers is described here, and comparisons are drawn between this and the first-mentioned technique. Prevailing winds are shown to be approximately the same for the two systems, but minor components can differ considerably. It is also shown that the integration time of the wind will have a marked effect on results. 相似文献
6.
Sonic anemometer path-averaging errors are determined for measurements of inertial-range velocity and temperature power spectra as a function of k
1 p, where k
1 is the streamwise wave number and p is the sonic path length. The attenuation of vertical velocity spectra is found to be quite similar for the CSAT3 and Solent anemometers and to be insensitive to wind direction. The attenuation of the horizontal wind component spectra is noticeably greater for the Solent sonics than for the CSAT3, but those for the CSAT3 have a greater dependence on wind direction. The attenuation of sonic temperature spectra is also found to be quite similar for the CSAT3 and Solent R3 sonics and to be insensitive to wind direction, while that of the Solent R2 is less than that of the other two sonics and has a minor dependence on wind direction. 相似文献
7.
Local Circulation Diurnal Patterns and Their Relationship with Large-Scale Flows in a Coastal Area of the Tyrrhenian Sea 总被引:1,自引:0,他引:1
Igor Petenko Giangiuseppe Mastrantonio Angelo Viola Stefania Argentini Lucia Coniglio Paolo Monti Giovanni Leuzzi 《Boundary-Layer Meteorology》2011,139(2):353-366
In order to characterise the local low-level circulation in the Tyrrhenian Sea coastal area near Rome, the wind field observed
by conventional anemometers, Doppler sodar, and rawinsonde has been analysed. The prevailing diurnal behaviour of wind speed
and direction as a function of season was highlighted, and the existence of two different patterns of the local circulation,
mainly due to land and sea breezes and to the drainage flow from the mouth of the Tiber valley, revealed. The comparison between
the low-level circulation and synoptic flow allowed us to determine the influence of the large-scale flow on nocturnal currents
that are observed at the Pratica di Mare site and the way that wind direction evolves during the day. Numerical simulations
are consistent with experimental data and depict the main features of the low-level wind field in the area. 相似文献
8.
9.
A meteorological tower significantly modifies the air flow, the mean windspeed and wind direction as well as the turbulencestructure of the air. Suchchanges can be noticed in particular in the wake region of the tower.Measurementson the 200 m tower ofForschungszentrum Karlsruhewere carried outusing Solent sonic anemometers in the lee of the towerand cup anemometers on both sides.In the wake region, spectral energydensity is increased in the high-frequency range. Superposition of this disturbance spectrum on the undisturbedspectrum yields a `knee' in the resulting spectrum. In the case of low turbulence intensity with stable stratification,a plateau with a constant energy content is observed in front of the knee.This effect is caused by the new production of turbulence energy from the mean flow as well as by an energy transfer fromlarger to smaller vortices. Power spectra in strongly stable conditionsshow a more rapid decrease of intensity in the region where the inertialsubrange is expected.The relevant scales of wake turbulence are derived from the maximum of the disturbance spectrum.Locations of the high-frequency peak do not depend on atmospheric stability,but are controlled mainly by mean wind speed.Apart from the reduction of the mean wind speed, the spectra and cospectra exhibit a strong anisotropy for such cases.The results demonstrate the significant influence of a tower on turbulence spectra in the wake region. 相似文献
10.
John Kochendorfer Tilden P. Meyers John Frank William J. Massman Mark W. Heuer 《Boundary-Layer Meteorology》2012,145(2):383-398
Sonic anemometers are capable of measuring the wind speed in all three dimensions at high frequencies (10–50 Hz), and are relied upon to estimate eddy-covariance-based fluxes of mass and energy over a wide variety of surfaces and ecosystems. In this study, wind-velocity measurement errors from a three-dimensional sonic anemometer with a non-orthogonal transducer orientation were estimated for over 100 combinations of angle-of-attack and wind direction using a novel technique to measure the true angle-of-attack and wind speed within the turbulent atmospheric surface layer. Corrections to the vertical wind speed varied from −5 to 37% for all angles-of-attack and wind directions examined. When applied to eddy-covariance data from three NOAA flux sites, the wind-velocity corrections increased the magnitude of CO2 fluxes, sensible heat fluxes, and latent heat fluxes by ≈11%, with the actual magnitude of flux corrections dependent upon sonic anemometer, surface type, and scalar. A sonic anemometer that uses vertically aligned transducers to measure the vertical wind speed was also tested at four angles-of-attack, and corrections to the vertical wind speed measured using this anemometer were within ±1% of zero. Sensible heat fluxes over a forest canopy measured using this anemometer were 15% greater than sensible heat fluxes measured using a sonic anemometer with a non-orthogonal transducer orientation. These results indicate that sensors with a non-orthogonal transducer orientation, which includes the majority of the research-grade three-dimensional sonic anemometers currently in use, should be redesigned to minimize sine errors by measuring the vertical wind speed using one pair of vertically aligned transducers. 相似文献
11.
用LSF1-1型测风仪测量一分钟一次瞬时风速记录分析表明,该测风仪可以粗略测量比较长周期的风速脉动变化,但精度较差。FL和Dyne测风仪由于它们灵敏度低,精度不够,不太合适测量小尺度风场的脉动变化。 相似文献
12.
Two Gill Solent Ultrasonic anemometers, models 1012R2 and 1210R3, weretested in field parallel measurements against a windvane based hot-film anemometerwith additional sensors for temperature and wet-bulb temperature, the MIUU (MIUU:Meteorology Institute, Uppsala University) instrument. This instrument was shown toretain its precision from laminar wind-tunnel tests when used in atmospheric turbulentflow. This contrasts strongly to the observed results for the two sonic anemometers,which were first calibrated in laminar wind-tunnel flow. Individual three-dimensionalcalibration matrices were constructed, and were shown to reduce the remaining calibration uncertainty for the wind speed to 0.4–0.8% for all azimuths and for angles of attack within ±40°. In the field intercomparison tests of the sonics against the MIUU instrument, it was found that the precision not only of the mean wind speed but of all second-order moments studied (variances and covariances, with and without temperature) deteriorated by a factor of typically three to four. Most of the scatter appears to be random, but in the case of the wind speed, a clear dependence on wind direction is found as well. It is concluded that the correction for the effect of the vertical supporting rods of the R2 and R3 instruments, which gives nearly perfect agreement for laminar flow, does not work entirely satisfactory in the natural turbulent flow. This, in turn, is likely to be so because of high sensitivity of the wake behind the cylindrical supporting rods to the character of the approach flow. 相似文献
13.
Observation of wind shear during evening transition and an estimation of submicron aerosol concentrations in Beijing using a Doppler wind lidar
下载免费PDF全文
![点击此处可从《Acta Meteorologica Sinica》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yong Chen Junling An Xiquan Wang Yele Sun Zifa Wang Jing Duan 《Acta Meteorologica Sinica》2017,31(2):350-362
The wind speed and direction measured over six months by a Doppler wind lidar (Windcube-8) were compared with wind cup anemometers mounted on the 325-m Beijing meteorological tower (BMT). Five mountain–plain wind cases characterized by wind direction shear were selected based on the high-frequency (1.1 s) wind profile of the Windcube-8 and analyzed with 1-h mesoscale surface weather charts. Also analyzed was the relationship between in-situ PM1 (aerodynamic diameter ≤ 1 μm) concentrations measured at 260 m on BMT and the carrier-to-noise ratio (CNR) of the co-located Windcube-8. The results showed that the 10-min averaged wind speed and direction were highly correlated (R = 0.96–0.99) at three matched levels (80, 140, and 200 m). The evening transition duration was 1–3 h, with an average wind speed of 1 m s–1 at 80 m above the ground. In addition, there was a zero horizontal-wind-speed zone along the wind direction shear line, and in one case, the wind speed was characterized by a Kelvin–Helmholtz gravity wave. The variability of the PM1 concentrations was captured by the CNR of the Windcube-8 in a fair weather period without the long-range transport of dust. 相似文献
14.
S. D. Smith 《Boundary-Layer Meteorology》1980,19(3):273-292
The most recent of a series of thrust anemometers, designed for measurement of wind turbulence and eddy fluxes and for long-term unattended operation, is evaluated. Calibration and data analysis procedures are outlined, and results of field trials are given, showing agreement with data from a sonic anemometer. 相似文献
15.
Sea surface wind stress and drag coefficients: The hexos results 总被引:17,自引:1,他引:17
Stuart D. Smith Robert J. Anderson Wiebe A. Oost C. Kraan Nico Maat Janice De Cosmo Kristina B. Katsaros Kenneth L. Davidson Karl Bumke Lutz Hasse Helen M. Chadwick 《Boundary-Layer Meteorology》1992,60(1-2):109-142
Turbulent fluxes have been measured in the atmospheric surface layer from a boom extending upwind from the Dutch offshore research platform Meetpost Noordwijk (MPN) during HEXMAX (Humidity Exchange over the Sea Main Experiment) in October–November, 1986. We started out to study eddy flux of water vapour, but discrepancies among simultaneous measurements made with three different anemometers led us to develop methods to correct eddy correlation measurements of wind stress for flow distortion by nearby objects. We then found excellent agreement among the corrected wind stress data sets from the three anemometers on the MPN boom and with eddy correlation measurements from a mast on a tripod. Inertial-dissipation techniques gave reliable estimates of wind stress from turbulence spectra, both at MPN and at a nearby ship. The data cover a range of wave ages and the results yield new insights into the variation of sea surface wind stress with sea state; two alternative formulas are given for the nondimensional surface roughness as a function of wave age. 相似文献
16.
B. B. Hicks 《Boundary-Layer Meteorology》1972,3(2):214-228
Even though propeller anemometers are found to give outputs which deviate from the desired cosine relationship by an amount which varies with wind speed, their overall performance is consistent with many atmospheric requirements. Their output per unit wind speed is a function of angle of attack, such that when used as sensors of the vertical or horizontal cross-wind components in the atmosphere, calibration factors may differ by as much as 30 % from those obtained in a normal wind-tunnel calibration procedure (in which wind velocity is parallel to the anemometer shaft). These characteristics are sufficiently important that great care should be taken in using these devices inu-v-w orthogonal arrays.For use in eddy-correlation equipment, it appears that it is best to vane-mount the horizontal sensor to ensure that the appropriate calibration factor is employed.The response lengths of propeller anemometers also vary with angle of attack. Near=0 °, the axially-referred response length appears to depend linearly on cos, but near=90 ° a dependence on cos1/2
fits the data. No strong effect of wind speed is found.Due to their limited response characteristics, these anemometers give rise to underestimates of the Reynolds stress measured near the surface. The extent of the loss is about 8 % when anemometers in good condition are employed at a height of 5m. Operation at a greater height would allow this error to be reduced. After exposure in the atmosphere for some time, the anemometers tend to respond more slowly and greater losses (of the order 25 %) can occur. Some improvement in performance is possible by the choice of a suitable spatial separation of the sensors. 相似文献
17.
Enrico Ferrero Stefano Alessandrini Francois Vandenberghe 《Boundary-Layer Meteorology》2018,168(2):289-319
We tested several planetary-boundary-layer (PBL) schemes available in the Weather Research and Forecasting (WRF) model against measured wind speed and direction, temperature and turbulent kinetic energy (TKE) at three levels (5, 9, 25 m). The Urban Turbulence Project dataset, gathered from the outskirts of Turin, Italy and used for the comparison, provides measurements made by sonic anemometers for more than 1 year. In contrast to other similar studies, which have mainly focused on short-time periods, we considered 2 months of measurements (January and July) representing both the seasonal and the daily variabilities. To understand how the WRF-model PBL schemes perform in an urban environment, often characterized by low wind-speed conditions, we first compared six PBL schemes against observations taken by the highest anemometer located in the inertial sub-layer. The availability of the TKE measurements allows us to directly evaluate the performances of the model; results of the model evaluation are presented in terms of quantile versus quantile plots and statistical indices. Secondly, we considered WRF-model PBL schemes that can be coupled to the urban-surface exchange parametrizations and compared the simulation results with measurements from the two lower anemometers located inside the canopy layer. We find that the PBL schemes accounting for TKE are more accurate and the model representation of the roughness sub-layer improves when the urban model is coupled to each PBL scheme. 相似文献
18.
超声测风仪因启动风速小、无转动部件、不破坏风场、测量精度高等特点,适用于多种行业的测风需求。超声波测风的相关检定规程当前在国内尚未正式制定。本文借鉴风杯检定规程所选择的风速测试点,在HDF-720低速回路风洞中,对超声测风仪在不同角度下进行了测试数据统计分析。结果表明:超声测风仪可以安装在工作段面较大的风洞中进行测试,由于超声探头存在阴影效应,对于同一风速,不同角度上的测量结果稍有差异,而且不同风速对应的差异也不同。利用超声测风仪进行风速实时测量时,必须结合上述测试分析,按照超声传感器的安装角度,对测量值进行相应修正。 相似文献
19.