Snöansamling

Snöansamling, or snow accumulation, is the amount of snow deposited on the ground that forms a snow cover. It results from snowfall exceeding the rate of melting, sublimation, and wind-driven loss, and it varies across locations and over time.

Formation and factors: The primary source is precipitation as snow. Net accumulation depends on air temperature near or below freezing, moisture content, and the duration of cold conditions. Wind can transport and redistribute snow, creating drifts and uneven coverage. Terrain features such as elevation, slope, aspect, and vegetation influence where snow settles and how quickly it melts, leading to spatially heterogeneous snowpacks.

Measurement and metrics: Snow depth is usually measured in centimeters or inches. Snow Water Equivalent (SWE) expresses the amount of liquid water contained in the snow, typically measured in millimeters or inches, and is a key metric for hydrology and flood forecasting. Monitoring methods include manual snow courses, snow pillows, automated gauges, and remote sensing techniques.

Snowpack evolution: After deposition, the snowpack undergoes metamorphism and compaction, changing density and stability. Processes include temperature-gradient metamorphism, grain growth, crust formation, and surface hoar development. Wind effects lead to further packing and layer formation, influencing avalanche risk and the mechanical properties of the snow.

Impacts and relevance: Snow accumulation affects hydrology by shaping runoff and groundwater recharge, influences ecosystem dynamics, and impacts infrastructure and transportation. It is a central focus in weather forecasting, avalanche advisories, and water-resource planning, particularly in regions with regular winter snowfall.