English Abstract For each station in the Air Quality Monitoring Network
in The Netherlands, where wind speed and wind direction are measured,
roughness length values were calculated from the standard deviation of wind
direction. The agreement between values presented here and those obtained
by other methods is good. The uncertainty is estimated to be a factor 2.
For each 1 x 1 km2, 5 x 5 km2 and 10 x 10 km2 gridcell over The Netherlands
roughness length values were estimated using detailed information about
landuse and forest characteristics. A comparison of these maps with those
presented in the literature showed good agreement. Comparison of the grid
average z0 values with those of the LML stations showed reasonable
agreement, except for those which are surrounded by roughness elements in
the near vicinity of the measuring location and for those which are situated
in areas with very low roughness lengths. The uncertainty in the grid
average z0 values is assumed to be about 40 - 60%.
