Frequency and magnitude biases in the 'Fryberger' model, with implications for characterizing geomorphically effective winds

Given the increased availability of more precise, unclassified wind data, most of these systematic frequency-magnitude biases can be avoided. Recommendations on reducing inaccuracies imposed by these biases include: (i) using to-the-degree wind data where available and categorizing into 16 equal 22.5° direction sectors, (ii) using either wind speed class statistical mean values or minimally classified whole knot values in DP calculations, and (iii) recognizing that converting 36-point (10 s of degrees) data to 16 direction classes may introduce a frequency bias toward the cardinal directions and will cause inaccuracies in DP and RDP estimates of an amount that depends on the wind regime. Further research is needed to assess the implications of such biases in different wind regimes and into the influence of localized supply- and transport-limiting factors on regional-scale assessments of dune morphodynamics and mobility. These findings are also relevant for other applications that use categorized wind speed-direction data such as dust or contaminant plume dispersion modelling.