The Application of Depletion Curves for Parameterization of Subgrid Variability of Snow

Charles H. Luce
David G. Tarboton, Utah State University


Parameterization of subgrid-scale variability in snow accumulation and melt is important for improvements in distributed snowmelt modelling. We have taken the approach of using depletion curves that relate fractional snow-covered area to element-average snow water equivalent to parameterize the effect of snowpack heterogeneity within a physically based mass and energy balance snowpack model. Comparisons of parameterization outputs with distributed model outputs and observations show performance comparable to the distributed model and reasonable performance relative to observations for time series modelling of snow water equivalent and snow-covered area. Examination of the relationship between the shapes of the depletion curves and parametric distributions shows that the shapes of dimensionless depletion curves depend primarily on the coefficient of variation and to a lesser extent on the shape of the snow distribution function. The methods presented here are a generalization of several previously used methods to estimate depletion curve shapes. Comparison of several years of observed depletion curves from the study basin show that the shapes of the depletion curves change little from year to year.