Snow covers approximately 45,000,000 km² of the Northern Hemisphere each winter, or approximately 47 percent of the total land mass of that region. This seasonal snow lasts anywhere from two to 10 months of the year, with its importance in climatic and hydrologic systems increasing with duration. Snow cover plays a crucial role in climate because it has such a high albedo, reflecting large amounts of solar energy. It is also a good thermal insulator, reducing winter soil freezing extent and playing a key role in the thermal balance of permafrost.
Numerous studies have documented the sensitivity of the climate system to changes in snow onset, melt timing, and snow extent and depth. Similarly, in the hydrologic system, snow cover provides up to 80 percent of the total runoff in some regions. For example, in the Western U.S., melting mountain snow packs provide much of the water for agriculture and power generation. In Alaska, where the snow lasts six to 10 months of the year, snow cover is critical to the overall functioning of the ecosystem and is embedded in the socio-economic system, where it affects transportation, construction schedules and cultural activities.
At the Geophysical Institute snow figures prominently in much of the research done by the Snow, Ice and Permafrost group. Specific projects focused on the snow cover itself include NSF-funded projects on snow instrumentation, joint NASA-NSF projects on mapping snow pack thickness using airborne LIDAR, and investigations into snow ecology (vegetation and animals).
(Photos by M. Sturm)