Coupled modelling of forest snow interception and sublimation

A series of process-based algorithms has been developed to describe the accumulation, unloading and sublimation of intercepted snow in forest canopies. These algorithms are unique in that they scale-up the physics of interception 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 sublimation in a southern boreal forest jack pine stand during late winter, found the coupled model provides reasonable approximations of both interception and sublimation losses on half-hourly, daily and event basis. Cumulative errors in estimate of intercepted snow load over 23 days of test were 0.05 mm SWE with a standard deviation of 0.46 mm SWE. Sublimation losses 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 the 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 can be a significant abstraction of water from mature evergreen stands in northern forests and that the losses can be calculated by application of process-based algorithms.