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Wind shear

About: Wind shear is a research topic. Over the lifetime, 8023 publications have been published within this topic receiving 185373 citations.


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Journal ArticleDOI
TL;DR: In this paper, a dynamic radiative model was used to study the influence of the geostrophic wind on the nocturnal cooling processes, and an important difference appeared between the top levels of the inversion and turbulent layers.
Abstract: A dynamic radiative model was used to study the influence of the geostrophic wind on the nocturnal cooling processes. For weak wind conditions, an important difference appears between the top levels of the inversion and turbulent layers. The dimensionless vertical profile of turbulent heat flux presents an important curvature at the beginning of the night; afterwards this profile varies little during the night.

58 citations

Journal ArticleDOI
TL;DR: An open-source model which can generate the power curve of any turbine, adapted to the specific conditions of any site, is developed and validated against the manufacturer power curves of 91 turbine models.

58 citations

Journal ArticleDOI
TL;DR: In this article, a probabilistic wind shear model based on the wind measurements is proposed for flat terrain and that can significantly decrease the uncertainty associated with fatigue load predictions for wind turbines with large rotors.
Abstract: We analyse high-frequency wind velocity measurements from two test stations over a period of several years and at heights ranging from 60 to 200 m, with the objective to validate wind shear predictions as used in load simulations for wind turbine design A validated wind shear model is thereby proposed for flat terrain and that can significantly decrease the uncertainty associated with fatigue load predictions for wind turbines with large rotors An essential contribution is the conditioning of wind shear on the 90% quantile of wind turbulence, such that the appropriate magnitude of the design fatigue load is achieved The proposed wind shear model based on the wind measurements is thereby probabilistic in definition, with shear jointly distributed with wind turbulence A simplified model for the wind shear exponent is further derived from the full stochastic model The fatigue loads over different turbine components are evaluated under the full wind measurements, using the developed wind shear model and with standard wind conditions prescribed in the IEC 61400-1 ed 3 The results display the effect of the Wohler exponent and reveal that under moderate turbulence, the effect of wind shear is most pronounced on the blade flap loads It is further shown that under moderate wind turbulence, the wind shear exponents may be over-specified in the design standards, and a reduction of wind shear exponent based on the present measurements can contribute to reduced fatigue damage equivalent loads on turbine blades Although the influence of wind shear on extreme loads was found to be negligible, the IEC 61400-1 wind shear definition was found to result in non-conservative estimates of the 50 year extreme blade deflection toward the tower, especially under extreme turbulence conditions Copyright © 2014 John Wiley & Sons, Ltd

58 citations

Journal ArticleDOI
01 Aug 1973-Tellus A
TL;DR: In this article, composited upper-air soundings have been constructed relative to 1 257 individual satellite-observed mesoscale (3-6° latitude) trade wind cloud clusters in the western tropical North Pacific.
Abstract: Composite upper-air soundings have been constructed relative to 1 257 individual satellite-observed mesoscale (3–6° latitude) trade wind cloud clusters in the western tropical North Pacific. Clusters have been stratified into five categories: pre-storm clusters (166 cases treated), developing clusters (211), conservative clusters (537), non-conservative clusters (135), and dying clusters (208). A sixth category has been specified for clear areas (553). Rawinsonde observations from 14 island stations for the two-year period of October 1966 to October 1968 provide composited data for 16 pressure levels from the surface to 30 mb. Approximately 12 000 observations make up the data sample. Computerized composited summaries for each group of clusters have been made from Northern Hemisphere Data Tabulations (NHDT) tapes for wind, vorticity, divergence, kinetic energy, temperature, moisture, stability, and isobaric heights. Mass and thermal balances are very well satisfied by the composited data. Significant differences in the low-level horizontal wind shears exist among the six categories. The pre-storm and developing clusters exhibit large low-level cyclonic shears, whereas the remaining cloud categories show weaker cyclonic shears. The clear areas show a marked anticyclonic low-level wind shear. The relative vorticities are mostly determined by shears of the zonal wind. East-west shears of the meridional wind are of secondary importance. These cloud clusters may be viewed as typical of the usual easterly trade wave only if the latter is primarily interpreted as a shearing phenomena of the zonal trade wind. These observations generally support the contention of the importance of low-level frictionally forced convergence in the zonal shearing environment north of the equatorial trough as the mechanism for producing and maintaining these clusters (some of which later develop into typhoons). DOI: 10.1111/j.2153-3490.1973.tb00617.x

58 citations

Journal ArticleDOI
TL;DR: In this article, the equilibrium range of surface wave energy spectra and wind measurements at Ocean Weather Station P (OWS-P, 50°N 145°W) were evaluated using a 3-week research cruise to OWS-P. Observations are consistent with a local balance between wind input and breaking dissipation.
Abstract: [1] Wave and wind measurements at Ocean Weather Station P (OWS-P, 50°N 145°W) are used to evaluate the equilibrium range of surface wave energy spectra. Observations are consistent with a local balance between wind input and breaking dissipation, as described by Philips (1985). The measurements include direct covariance wind stress estimates and wave breaking dissipation rate estimates during a 3 week research cruise to OWS-P. The analysis is extended to a wider range of conditions using observations of wave energy spectra and wind speed during a 2 year mooring deployment at OWS-P. At moderate wind speeds (5–15 m/s), mooring wave spectra are in agreement, within 5% uncertainty, with the forcing implied by standard drag laws and mooring wind measurements. At high wind speeds (>15 m/s), mooring wave spectra are biased low, by 13%, relative to the forcing implied by standard drag laws and mooring wind measurements. Deviations from equilibrium are associated with directionality and variations at the swell frequencies. A spectral wave hindcast accurately reproduces the mooring observations, and is used to examine the wind input.

58 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023155
2022347
2021165
2020157
2019187
2018165