Background

The ablation of snow cover is an important contributor to crucial hydrologic variables such as streamflow, soil moisture, and groundwater supplies. In regions with discontinuous snow cover the number and magnitude of ablation events vary greatly from one season to another. Even in stream basins that are characterized by a single large melt event each season, estimates of the size and time of occurrence of peak flows changes dramatically from one year to the next. Seasonal variations in the frequency and magnitude of large ablation events are important as they can lead to severe environmental and societal consequences. These consequences may manifest themselves as snowmelt-induced floods, lack of streamflow in snowmelt fed rivers, and transport of pollutants or excess nutrients in rapid snowmelt events, to name a just few. Little research has been conducted on understanding the connection between the frequency and magnitude of ablation events and the role of global-scale atmospheric and oceanic forcings in their variation. Moreover, the pathways that link global-scale forcings to basin-scale snow hydrology are poorly understood as is the manifestation of snow-induced streamflow variability in future climate scenarios.