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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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TL;DR: In this paper, a wind turbine operating in the wake of an upstream wind turbine was investigated with the objective of identifying the load generating changes in the wind field parameters compared to a free flow situation.

176 citations

Journal ArticleDOI
TL;DR: In this article, a wind-tunnel investigation of the wind flow over two-dimensional forward-facing escarpments is reported as part of a continuing research programme into the effects of local topography on wind flow close to the ground.
Abstract: A wind-tunnel investigation of the wind flow over two-dimensional forward-facing escarpments is reported as part of a continuing research programme into the effects of local topography on the wind flow close to the ground. Four sharp-edged escarpments with their slopes varying between a cliff and a 4:1 gradient, were placed normal to a simulated neutrally-stable rural boundary layer which was modelled to a scale of 1:300. The resulting flows close to the surfaces of the escarpments were measured with a hot-wire anemometer. The modifications to the mean wind speed, turbulence intensity and energy spectra over the escarpments are described. The results indicate the extent and magnitude of the modification to the flow and suggest that significant changes in turbulence characteristics only occur in the wake region close behind the crest, where a shift of energy to higher frequencies is evident.

176 citations

Journal ArticleDOI
TL;DR: In this paper, the authors reexamined the swirling wind structure of tropical cyclone (TC) by utilizing flight-level observations collected from Atlantic and eastern Pacific storms during 1977-2.
Abstract: Recent theoretical studies, based on vortex Rossby wave (VRW) dynamics, have established the importance of the radial structure of the primary circulation in the response of tropical cyclone (TC)–like vortices to ambient vertical wind shear. Linear VRW theory suggests, in particular, that the degree of broadness of the primary circulation in the near-core region beyond the radius of maximum wind strongly influences whether a tilted TC vortex will realign and resist vertical shear or tilt over and shear apart. Fully nonlinear numerical simulations have verified that the vortex resiliency is indeed sensitive to the initial radial structure of the idealized vortex. This raises the question of how well the “true” nature of a TC’s primary circulation is represented by idealized vortices that are commonly used in some theoretical studies. In this paper the swirling wind structure of TCs is reexamined by utilizing flight-level observations collected from Atlantic and eastern Pacific storms during 1977–2...

176 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed fundamental explanations of the genesis, structure, and implications of low-level meso-g-scale surface vortices within quasi-linear convective systems (QLCSs) such as squall lines and bow echoes.
Abstract: This two-part study proposes fundamental explanations of the genesis, structure, and implications of lowlevel meso-g-scale vortices within quasi-linear convective systems (QLCSs) such as squall lines and bow echoes. Such ‘‘mesovortices’’ are observed frequently, at times in association with tornadoes. Idealized simulations are used herein to study the structure and evolution of meso- g-scale surface vortices within QLCSs and their dependence on the environmental vertical wind shear. Within such simulations, significant cyclonic surface vortices are readily produced when the unidirectional shear magnitude is 20 m s 21 or greater over a 0‐2.5- or 0‐5-km-AGL layer. As similarly found in observations of QLCSs, these surface vortices form primarily north of the apex of the individual embedded bowing segments as well as north of the apex of the larger-scale bow-shaped system. They generally develop first near the surface but can build upward to 6‐8 km AGL. Vortex longevity can be several hours, far longer than individual convective cells within the QLCS; during this time, vortex merger and upscale growth is common. It is also noted that such mesoscale vortices may be responsible for the production of extensive areas of extreme ‘‘straight line’’ wind damage, as has also been observed with some QLCSs. Surface vortices are also produced for weaker shears but remain shallow, weak, and short-lived. Although similar in size and strength to mesocyclones associated with supercell storms, and also sometimes producing similar hooklike structures in the rain field, it is also shown that the present vortices are quite distinct, structurally and dynamically. Most critically, such vortices are not associated with long-lived, rotating updrafts at midlevels and the associated strong, dynamically forced vertical accelerations, as occur within supercell mesocyclones.

175 citations

Journal ArticleDOI
TL;DR: In this paper, the trade wind field over the Pacific Ocean between 30°N and 30°S has been studied on the basis of five million wind observations made from ships and data were sorted by quadrangles of 2° latitude and 10° longitude to resolve north-south gradients in the wind field adequately.
Abstract: The trade wind field over the Pacific Ocean between 30°N and 30°S has been studied on the basis of five million wind observations made from ships. Data were sorted by quadrangles of 2° latitude and 10° longitude to resolve north-south gradients in the wind field adequately. Maps of the surface wind stress vector for February and August are presented and the development of the field throughout the year is discussed. The trade wind regime in each hemisphere is largest and strongest during the respective winter and spring. The area covered by northeast trades is smaller than the area covered by southeast trades, but the northeast trades have a stronger mean wind stress and a larger annual variation both in area and mean stress. The computed divergence of the wind velocity revealed a little known area of convergence in the southeastern Pacific near the equator. The curl of the wind stress and the meridional profile of zonal wind stress vary considerably during the year. The minimum in zonal stress be...

175 citations


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