Coupled modelling of forest snow interception and sublimation

A series of process-based algorithms has been developed to describe the acc umulation, unloading and sublimation of intercepted snow in forest canopies . These algorithms are unique in that they scale up the physics of intercep tion and sublimation from small scales, where they are well understood, to forest stand-scale calculations of intercepted snow sublimation. Evaluation of results from the set of algorithms against measured interception and su blimation, in a southern boreal forest jack pine stand during late winter, found that the coupled model provides reasonable approximations of both int erception and sublimation losses on half-hourly, daily and event bases. Cum ulative errors in the estimate of intercepted snow load over 23 days of tes t were 0.06 mm SWE, with a standard deviation of 0.46 mm SWE, Sublimation l osses during the evaluation were high, approximately two-thirds of snowfall within this period. Seasonal intercepted snow sublimation as a portion of annual snowfall at the model test site was lower than sublimation during th e tests, ranging from 13% for a mixed spruce-aspen, 31% for the mature pine and 40% for a mature spruce stand. The results indicate that sublimation c an be a significant abstraction of water from mature evergreen stands in no rthern forests and that the losses can be calculated by application of proc ess-based algorithms. (C) 1998 John Wiley & Sons, Ltd.