A Comparison of Several “Single-Pass” Estimators of the Standard Deviation of Wind Direction

AbstractComputation of the standard deviation of wind direction σθ generally requires repeated consideration of the individual measurements of wind direction. This need for multiple passes through the data sample can create a storage problem for small or remote data acquisition systems. Statistical quantities that can be computed during a single pass through incoming wind speed and direction data are first reviewed, and relationships between these quantities are discussed. A single-pass estimator for σθ is then developed and found to correspond to within ±2% of conventional, two-pass σθ computations for unimodal angular distributions spanning the full σθ range of from 0 to 103.9°. Similar comparisons are presented for other, recently proposed estimators of σθ.