Topic
Wind shear
About: Wind shear is a research topic. Over the lifetime, 8023 publications have been published within this topic receiving 185373 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this article, the authors evaluate the power law with respect to wind data taken on a 25 m mast on the central Mediterranean island of Malta and derive a site-specific factor affiliated to a typical terrain type.
116 citations
115 citations
TL;DR: In this paper, the authors measured wind speed, temperature, and turbulent fluxes of heat and momentum in the lowest 32 m at a station on an antarctic ice shelf and deduced the length scales of turbulence within this layer from vertical velocity power spectra.
Abstract: Profiles of wind speed, temperature and turbulent fluxes of heat and momentum in the lowest 32 m have been measured at a station on an antarctic ice shelf. During the antarctic winter the surface layer often shows strong static stability, with temperature gradients as large as 1 Km−1 in the lowest few metres. the surface inversion is destroyed during periods of high wind speed but the wind profile shows significant deviation from the expected logarithmic form under such conditions. Measurements of stress at 5 m indicate that the roughness length of the snow surface is about lO−4 m.
At 5 m height, the variations of the dimensionless wind shear, ϕm, and potential temperature gradient, ϕT, agree with previously determined forms of the Monin-Obukhov similarity functions. Above 5 m, the behaviour of ϕm and ϕT is only qualitatively similar and surface-layer similarity theory does not provide a good description of the profiles.
Turbulence length scales have been deduced from vertical velocity power spectra. Under near-neutral conditions, the ratio of turbulence length scale to measurement height is observed to decrease with increasing height of measurement. This observation is consistent with the variation of turbulence length scale with height implied by the measurements of ϕm. It is suggested that the stability of the overlying atmosphere restricts the depth of the turbulent boundary layer and hence the length scales of turbulence within this layer. Increasing stability causes a decrease of turbulence length scales at all levels.
The ratios of turbulence kinetic energy to stress and temperature variance to heat flux are examined. Measurements are somewhat scattered, but the distribution of values varies little with height or stability. the form of the distribution suggests that large-scale motions, possibly internal gravity waves, may be playing an important role in boundary-layer processes.
115 citations
TL;DR: In this article, the authors examined thresholds of sand movement, intermittency and the relationship between fluctuating winds and transport intensity based on high frequency measurements of wind speed and saltation and found that sand transport was highly intermittent early in the day when winds were only slightly above threshold and became more continuous towards the upper beach because of increasing fetch distance and decreasing surface moisture.
114 citations
114 citations