Estimators for the standard deviations of lateral, longitudinal and vertical wind components

The dispersion of air pollutants can be described by the standard deviations of lateral, longitudinal and vertical wind components. As the lateral and longitudinal standard deviations are rarely reported by measurement systems, they must be estimated from other, directly measured quantities. Several such estimators are derived from a simple isotropic Gaussian model of turbulent wind fluctuations. They are compared with other estimators taken from the literature. A large dataset from an ultrasonic anemometer is used to determine which estimators have smallest errors and are most robust under a variety of atmospheric conditions. Many measurement systems do neither report the vertical standard deviation nor any other information of vertical wind components. Therefore, several methods are discussed to estimate the vertical standard deviation from horizontal turbulence parameters