Processes Governing the Ablation of Intercepted Snow

Abstract Interception and ablation of snow in forest canopies significantly influence the quantity, timing, and phase of precipitation that reaches the ground in cold regions forests. Yet current modeling approaches have uncertain transferability across differing climate and forest types. Here, in situ observations from a needleleaf forest in the Canadian Rockies were utilized to evaluate the theories underpinning existing canopy snow ablation models and develop a novel understanding supporting the development of a new canopy snow ablation model. The observations revealed that canopy snow load, wind shear stress, and canopy snowmelt are strongly associated with unloading; however, air temperature and sublimation are not. A new canopy snow ablation model was developed based on these associations and their impact on the canopy snow energy and mass balance. This model demonstrated improved performance in simulating canopy snow load compared with previous approaches, especially during melt‐ and wind‐dominated ablation events. The improved performance in predicting canopy snow load across a wide range of meteorological conditions, compared to existing models, is due to including a comprehensive representation of the mass and energy balance of intercepted snow. In contrast, all existing canopy snow models were found to omit key processes which limited their accuracy in simulating snow load, its ablation and partitioning to sublimation, melt, drip, and unloading.