DETERMINATION OF TIMING AND LOCATION OF WATER-MOVEMENT AND ICE-LAYER FORMATION BY TEMPERATURE-MEASUREMENTS IN SUB-FREEZING SNOW

Measurements of temperature in snow along a vertical profile during th e onset of spring melting are used to calculate spatial and temporal t emperature gradients and terms of the conduction equation with an inte rnal energy-production term are calculated. Heat-transfer information is combined with stratigraphic observations made during melting and al low detailed determination of the timing and location of heterogeneous water movement and of refreezing. Internal energy production is inter preted as latent heat of refreezing of percolated melt water. Times an d locations of flow and refreezing of meltwater are calculated and com pared to stratigraphic observations of layering and changes in density and liquid-water content. Sequences of melt, piping, layering and ref reezing seen in calculations and in stratigraphy demonstrate retarded flow at fine-to-coarse transitions, flow along such transitions and re freezing at the transitions to form ice layers. Downslope flow is also observed in the absence of an impermeable horizon to redirect flow fr om the vertical.