windgrepen

Windgrepen is a term used in wind science to describe localized, short-duration increases in wind speed and turbulence. The concept is used to discuss gust-like events that occur on the scale of seconds to minutes and at specific locations, such as near hills, valleys, ridges, coastlines, or urban canyons. The term is not part of formal meteorological nomenclature in all regions, and its exact definition can vary among researchers.

Causes: Windgrepen arise when atmospheric flow interacts with terrain or obstacles. Channeling effects in valleys and gaps can accelerate flow, while shear at fronts or thermal plumes can induce sudden gusts. Urban roughness and obstacles can create gusty patches that are not well predicted by coarse models.

Measurement and analysis: They are detected with fast-response sensors, such as 1 Hz or faster anemometers, sonic anemometers, or lidar/radar that can capture short-lived fluctuations. Analyses focus on gust factor, gust duration, and turbulence intensity to assess loads on structures and safety.

Applications and implications: In civil and coastal engineering, wind engineering, and wind energy, understanding windgrepen helps with design, siting, and operation. They can influence building design, turbine control, and weather warnings for high-frequency gusts. In maritime contexts, gusts can affect sailing conditions and harbor operations.

See also: gust, wind gust, gust factor, microclimate, wind shear.