Point simulation of seasonal snow cover dynamics beneath boreal forest canopies

Abstract

The accurate simulation of snowpack deposition and ablation beneath forested areas is complicated by the fact that the vegetation canopy strongly affects the snow surface energy balance. Data collected as part of the Boreal Ecosystem-Atmosphere Study are used to derive a series of simple canopy adjustments and drive a two-layer coupled energy- and mass-balance snowmelt model to simulate the deposition and ablation of the seasonal snowpack at six sites within the boreal forest for the 1994-1995 snow season. Snow cover energy gain in the spring is strongly controlled by canopy cover and is dominated by net radiation fluxes which contribute from 66% to 92% of the snow cover energy balance. Turbulent fluxes comprise 11% of the net energy balance on average, with minor contributions from soil and advected energy fluxes. Simulated depths at the forested sites generally show good agreement with measured snow depths, indicated by model efficiencies ranging from 0.90 to 0.94, with root-mean-square differences less than 5 cm. Seasonal snow covers in the boreal environment may be more sensitive to land use transitions, rather than climate shifts, due to the strong control exerted by vegetation canopies on radiation transfer processes. Copyright 1999 by the American Geophysical Union.