摘要：Spatial and temporal variations in aerodynamic roughness length (z 0 ) on Haut Glacier d’Arolla, Switzerland, during the 1993 and 1994 ablation seasons are described, based on measurements of surface microtopography. The validity of the microtopographic z 0 measurements is established through comparison with independent vertical wind profile z 0 measurements over melting snow, slush and ice. The z 0 variations are explained through correlation and regression analyses, using independent measurements of meteorological and surface variables, and parameterizations are developed to calculate z 0 variations for use in surface energy-balance melt models. Several independent variables successfully explain snow z 0 variation through their correlation with increasing surface roughness, caused by ablation hollow formation, during snowmelt. Non-linear parameterizations based on either accumulated melt or accumulated daily maximum temperatures since the most recent snowfall explain over 80% of snow z 0 variation. The z 0 following a fresh snowfall on an ice surface is parameterized based on relationships with the underlying ice z 0 , snow depth and accumulated daily maximum temperatures. None of the independent variables were able to successfully explain ice z 0 variation. Although further comparative studies are needed, the results lend strong support to the microtopographic technique of measuring z 0 over melting glacier surfaces.
