Scale-dependent roughness of a glacier surface: implications for radar backscatter and aerodynamic roughness modelling

The roughness of the snow-free surface of the glacier midre Lovénbreen, Svalbard, has been investigated on scales between 1 mm and 300 m. It is shown that the roughness is reasonably well described by scale-free (fractal) models for scales longer than a few metres and shorter than about 100 mm. However, there is a break in the behaviour between these scales which can be characterized by a definite scale length of 70–500 mm and a root-mean-square height variation between around 6 and 70 mm. The aerodynamic roughness length contributed by these features is estimated to be 0.3–1.5 mm. Features on this scale are consistent with the observed microwave backscattering properties of the glacier.