Routing of canopy drip in the snowpack below a spruce crown

Abstract

Snow that is retained by a forest canopy may either sublimate or evaporate directly from the crown or drop as snow clumps or meltwater to the ground. Redistributed snow and meltwater aect the snow structure and prevent the formation of mechanically weak layers, which is the prerequisite for avalanche formation in forests. In this paper we describe the results of dye tracer experiments conducted in a subalpine forest near Davos, Switzerland. Before a snowfall event we stained snow-free branches of a spruce with a dye tracer solution. After snowfall the coloured meltwater dripping from the branches down on to the snowpack stained the percolation pathways of the meltwater in the snowpack. Photographs of the snow pro®les indicate that the meltwater seeped almost vertically through the isothermal snowpack to the soil surface not exceeding the projected crown edge. Meltwater of dierent events moves along dierent preferential¯ow channels in the snow suggesting that old channels are not non-conducting and additional meltwater fronts create new channels.

Canopy and Terrain Interactions Affecting Snowpack Spatial Patterns in the Sierra Nevada of California

“…This explains that the shallowest snowpack can usually be observed around the tree bole because of the heat emitted. Also, more meltwater drip exists around the tree bole than the drip edge because more snow was intercepted during snow accumulation around the tree bole area, which accelerates the snowmelt on the ground (Bründl et al, 1999). Thus, from equation ( 9), the total longwave radiation that enters the snow surface in the upslope direction under canopy will be higher, which is consistent with the observed centers of mass of tree wells being downslope (Figures 5 and 6).…”

“…during snow accumulation around the tree bole area, which accelerates the snowmelt on the ground (Bründl et al, 1999). Thus, from equation 9, the total longwave radiation that enters the snow surface in the upslope direction under canopy will be higher, which is consistent with the observed centers of mass of tree wells being downslope ( Figures 5 and 6).…”

Impact of rain-on-snow events on snowpack structure and runoff under a boreal canopy

“…5, which demonstrate that ROS events may result in preferential flow under the canopy. The presence of percolation channels in the sub-canopy snowpack was also observed in other studies (Bründl et al, 1999;Teich et al, 2019). Percolation channels are formed in cold snowpacks before matrix flow takes over as the snowpack warms and wet snow metamorphism prevails (Hirashima et al, 2019).…”

Avalanche Protection Forest: From Process Knowledge to Interactive Maps

“…There are essentially four physical processes that contribute to the stabilization of the snow cover in forests: (1) Interception of falling snow: snow is partly intercepted on branches and sublimated back into the atmosphere [12]. Intercepted snow, which is not sublimated, enters the snowpack in the form of snow lumps or meltwater [13]. (2) More balanced radiation regime: the duration of solar radiation and the long-wave radiation during the night are reduced in forests compared to open field [14,15].…”