water equivalent

Snow scientists typically excavate a snow pit within which to make basic measurements and observations. Observations can describe features caused by wind, water percolation, or snow unloading from trees.Water percolation into a snowpack can create flow fingers and ponding or flow along capillary barriers, which can refreeze into horizontal and vertical solid ice formations within the snowpack. Among the measurements of the properties of snowpacks (together with their codes) that the International Classification for Seasonal Snow on the Ground presents are:^[14]

• Height (H) is measured vertically from the ground surface, usually in centimeters.
• Thickness (D) is snow depth measured at right angles to the slope on inclined snow covers, usually in centimeters.
• Height of snowpack (HS) is the total depth of the snowpack, measured vertically in centimetres from base to snow surface.
• Height of new snow (HN) is the depth in centimeters of freshly fallen snow that accumulated on a snow board during a period of 24 hours or some other, specified period.
• Snow water equivalent (SWE) is the depth of water that would result if the snow mass melted completely, whether over a given region or a confined snow plot, calculated as the product of the snow height in meters times the vertically-integrated density in kilograms per cubic meter.
• Water equivalent of snowfall (HNW) is the snow water equivalent of snowfall, measured for a standard observing period of 24 hours or other period.
• Snow strength (Σ) whether compressive, tensile, or shear, snow strength can be regarded as the maximum stress snow can withstand without failing or fracturing, expressed in pascals per second, squared.
• Penetrability of snow surface (P) is the depth that an object penetrates into the snow from the surface, usually measured with a Swiss rammsonde, or more crudely by a person standing or on skis, in centimeters.
• Surface features (SF) describes the general appearance of the snow surface, owing to deposition, redistribution and erosion by wind, melting and refreezing, sublimation and evaporation, and rain. The following processes have the corresponding results: smooth—deposition without wind; wavy—wind deposited snow; concave furrows—melt and sublimation; convex furrows—rain or melt; random furrows—erosion.
• Snow covered area (SCA) describes the extent of snow-covered ground, usually expressed as a fraction (%) of the total.
• Slope angle (Φ) is the angle measured from the horizontal to the plane of a slope with a clinometer.
• Aspect of slope (AS) is the compass direction towards which a slope faces, normal to the contours of elevation, given either degrees from true North N = 0° = 360° or as N, NE, E, SE, S, SW, W, NW.
• Time (t) is usually given in seconds for a measurement duration or in longer units to describe the age of snow deposits and layers.