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Wind and windstorms cause severe damage to natural and human-made environments. Thus, wind-related risk assessment is vital for the preparation and mitigation of calamities. However, the cascade of events leading to damage depends on many factors that are environment-specific and the available methods to address wind-related damage often require sophisticated analysis and specialization. Fortunately, simple indices and thresholds are as effective as complex mechanistic models for many applications. Nonetheless, the multitude of indices and thresholds available requires a careful selection process according to the target environment. Here, we first provide a basic background on wind and storm formation and characteristics, followed by a comprehensive collection of both indices and thresholds that can be used to predict the occurrence and magnitude of wind and storm damage. We focused on five key environments: forests, urban, transport, agriculture, and wind-based energy production. For each environment we described indices and thresholds relating to physical properties such as topography and land cover but also to economic aspects (e.g. disruptions in transportation or energy production). In the face of increased climatic variability, the promotion of more effective analysis of wind and storm damage could reduce the impact on society and the environment. [ABSTRACT FROM AUTHOR]

An attempt is made to compare results of large-eddy simulation (LES) in a convective boundary layer using the model PALM with experimental data obtained from acoustic travel time tomography. This method provides two-dimensional data arrays, which are considered as more suitable for LES-validation than classical local or line-integrated measurements, because the tomographic data are area- or volume-averaged. For a quantitative comparison with experimental data in general, some prerequisites have to be considered: First of all, the initial and boundary conditions of the LES model have to be provided correctly by the experiment. Considering measurement errors, a sensitivity study was performed to investigate the influence of inaccurate initial and boundary conditions on the simulation results. This showed that for determining some boundary conditions, such as the surface temperature and the roughness length, high measurement accuracies are necessary, which are difficult to reach or which at least require considerable extra measurement efforts. The initial and boundary conditions provided by the Lindenberg experiment in 1999 turned out to be of insufficient accuracy to allow quantitative comparisons. However, a qualitative comparison was performed instead to investigate if the acoustic tomography method is a proper method for comparisons with LES models in general. It showed a good qualitative agreement with some quantitative differences. These differences can partly be explained by the sensitivity of the LES to initial and boundary conditions and by the limitations of the acoustic tomography. [ABSTRACT FROM AUTHOR]

Acoustic travel time measurements are used to investigate the spatial and temporal variability of air temperature and wind fields in the atmospheric surface layer. The observational system consists of several sound sources and receivers, which were distributed over an apparently horizontal homogeneous terrain to calculate a two-dimensional distribution of air temperature using a tomographic algorithm. Parallel to the tomographic measurements, all components of the energy balance of the investigated surface are observed using conventional micrometeorological methods. The sum of these components of the energy balance must theoretically be equal to zero. However, the sum of the observed components often add up to an unexplainable residuum. It can be shown here that the diurnal variability of the residuum of such energy balance measurements and the simultaneously observed diurnal variability of the horizontal gradients in the air temperature field seem to be closely related. This is a hint that the known difficulties in observing a closed energy balance with conventionally micrometeorological methods could be due to the disregarding of the horizontal nonhomogeneous airflow conditions. [ABSTRACT FROM AUTHOR]