A model is presented for the simulation of snowmelt under a subarctic spruce tree, making use of the physical processes associated with melt, the geometry of the canopy, and empirical functions and coefficients obtained from the field. This model allows detailed study of the effect of a tree on the micropattern of snow ablation. Simulated results compare well with the daily snow depths measured along transects that extend in two directions outward from the tree trunk. Radiation represents the principal component of the total melt energy, and the tree canopy enhances the longwave radiation balance for the snow surface. Strong asymmetry in melt rates among different azimuths within and beyond the tree canopy is simulated and can be explained by the changing intensities of the snowmelt processes due to the presence of a tree. ¿ 2000 American Geophysical Union