The extent and variability of seasonal snow cover are important parameters in the climate system, due to their effects on energy and moisture budgets, and because surface temperature is highly dependent on snow cover. In turn, snow cover trends serve as key indicators of climate change. Many distinct techniques have become available to study snow-climate relationships. Satellites provided the first capability for monitoring snow cover extent at continental and hemispheric scales, and there have been rapid advances in snow modeling physics to represent snow cover and snow processes in Global...