A Simple Method for Determining the Standard Deviation of Wind Direction

Abstract

The discontinuity of the wind direction at 360° complicates automatic calculations of some atmospheric parameters. Various methods were suggested to obtain the standard deviation of the wind direction (σ?). They are reviewed and a simple, once through calculation procedure is suggested, giving the exact σ? without any hypotheses on the wind direction distribution. The discussion stresses, however, that automatically computed σ? values are not always meaningful, in several different situations frequently occurring in the atmosphere.