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- Log_wind_profile abstract "The Log wind profile is a semi-empirical relationship commonly used to describe the vertical distribution of horizontal mean wind speeds within the lowest portion of the planetary boundary layer. The relationship is well described in the literature.The logarithmic profile of wind speeds is generally limited to the lowest 100 m of the atmosphere (i.e., the surface layer of the atmospheric boundary layer). The rest of the atmosphere is composed of the remaining part of the planetary boundary layer (up to around 1000 m) and the troposphere or free atmosphere. In the free atmosphere, geostrophic wind relationships should be used.The equation to estimate the mean wind speed at height (meters) above the ground is:where is the friction (or shear) velocity (m s−1), is the Von Kármán constant (~0.41), is the zero plane displacement, is the surface roughness (in meters), and is a stability term where is the Monin-Obukhov stability parameter. Under neutral stability conditions, and drops out.Zero-plane displacement is the height in meters above the ground at which zero wind speed is achieved as a result of flow obstacles such as trees or buildings. It is generally approximated as 2/3 of the average height of the obstacles. For example, if estimating winds over a forest canopy of height h = 30 m, the zero-plane displacement would be d = 20 m.Roughness length is a corrective measure to account for the effect of the roughness of a surface on wind flow, and is between 1/10 and 1/30 of the average height of the roughness elements on the ground. Over smooth, open water, expect a value around 0.0002 m, while over flat, open grassland ≈ 0.03 m, cropland ≈ 0.1-0.25 m, and brush or forest ≈ 0.5-1.0 m (values above 1 m are rare and indicate excessively rough terrain).The log wind profile is generally considered to be a more reliable estimator of mean wind speed than the Wind profile power law in the lowest 10–20 m of the planetary boundary layer. Between 20 m and 100 m both methods can produce reasonable predictions of mean wind speed in neutral atmospheric conditions. From 100 m to near the top of the atmospheric boundary layer the power law produces more accurate predictions of mean wind speed (assuming neutral atmospheric conditions).The neutral atmospheric stability assumption discussed above is reasonable when the hourly mean wind speed at a height of 10 m exceeds 10 m/s where turbulent mixing overpowers atmospheric instability.".
- Log_wind_profile wikiPageID "4971619".
- Log_wind_profile wikiPageRevisionID "602572328".
- Log_wind_profile hasPhotoCollection Log_wind_profile.
- Log_wind_profile subject Category:Atmospheric_dispersion_modeling.
- Log_wind_profile subject Category:Boundary_layer_meteorology.
- Log_wind_profile comment "The Log wind profile is a semi-empirical relationship commonly used to describe the vertical distribution of horizontal mean wind speeds within the lowest portion of the planetary boundary layer. The relationship is well described in the literature.The logarithmic profile of wind speeds is generally limited to the lowest 100 m of the atmosphere (i.e., the surface layer of the atmospheric boundary layer).".
- Log_wind_profile label "Log wind profile".
- Log_wind_profile label "Logarithmisches Windprofil".
- Log_wind_profile sameAs Logarithmisches_Windprofil.
- Log_wind_profile sameAs m.0cxv1n.
- Log_wind_profile sameAs Q1471886.
- Log_wind_profile sameAs Q1471886.
- Log_wind_profile wasDerivedFrom Log_wind_profile?oldid=602572328.
- Log_wind_profile isPrimaryTopicOf Log_wind_profile.