Aerodynamic and surface characteristic length scales of snow covered flat planes

Velocity profiles over fresh fallen snow surfaces have been measured in the SLF cold atmospheric boundary layer wind tunnel. Aerodynamic roughness lengths z0 have been estimated from log-law velocity profile fitting. In parallel, photographs of the snow surfaces have been taken and evaluated using digital image analysis giving snow surface contour line coordinates. Applying structure functions to the snow surface coordinates and statistical fitting analyses resulted in sets of surface characteristic length scales (random field approach). The synthesis of both approaches suggests a linear relationship between z0 and one of the surface characteristic length scales