The annual mean wind speed value we provide is our best estimate of the actual mean value. The +/- (plus or minus) symbol indicates that the true annual mean value is within a range plus or minus the number shown after the provided wind speed value. The Prospecting Tools directly incorporate a confidence interval for the annual mean wind speed data, showing a range of expected wind speed values, to provide a realistic assessment. We are 68% confident that the true annual mean wind speed for a given location falls inside the displayed range. The narrower the range of wind speeds, (i.e. the smaller the +/- value we show) the more confidant we are concerning the long-term annual mean wind speed value.

For any location, the annual mean range is only meant to be used at the prospecting stage and doesn’t present the full story of a potential site. Data on annual and diurnal variability, prevailing wind direction, and many other atmospheric factors are necessary to more accurately assess the wind resource at any given location. In order to more thoroughly understand the wind resource at a location, we recommend a FirstLook Standard Wind Report or FirstLook Professional Wind Report. For an even more precise estimate, 3TIER’s FullView Wind Site Climate Variability Analysis can incorporate your observational data.