snowcover

Snow cover refers to the portion of the land surface that is covered by snow at a given time. It forms when atmospheric precipitation falls as snow and accumulates, persisting when temperatures stay at or below freezing. Snow cover is dynamic, with wind redistributing snow, solar radiation driving melt and sublimation, and metamorphism changing grain size, density, and bonding, which in turn affect insulation and hydraulic properties.

Snow cover plays a major role in the hydrologic cycle and climate system. It stores a portion of annual precipitation as a freshwater reservoir, delaying runoff and shaping river flows during melt periods. The high albedo of snow reduces absorbed solar energy, influencing surface energy balance and regional climate feedbacks. Snowpack also insulates the soil and vegetation, affecting soil temperature and plant activity during winter and spring.

Measurement and monitoring of snow cover combine remote sensing and in-situ observations. Remote sensing tracks snow extent and snow cover fraction, using optical sensors for presence or absence and microwave sensors to estimate snow water equivalent. Ground networks provide snow depth, density, and SWE data through snow pillows, probes, and manual snow courses. Global datasets and maps synthesize these observations to show seasonal and interannual variations.

Snow cover is consequential for ecosystems, transportation, and agriculture, and it presents hazards such as avalanches and road closures. Changes in snow cover extent and duration are linked to climate variability and change, with regional shifts in melt timing, reductions in persistence in some areas, and greater variability in others.