Snow is a critical water resource used by billions of people worldwide. Snow water resources are measured as snow water equivalent (SWE) – the amount of liquid water released by melting the snowpack. Snow is also a key element in the Earth’s climate cooling system because it is such an effective reflector of sunlight. Most of this cooling effect is at higher latitudes in the Northern Hemisphere and is largely determined by snow accumulation and persistence.  Furthermore, rapid snowmelt, either alone or compounded with rainfall, has caused devastating floods, leading to destruction of property and debilitating economic losses amounting to hundreds of billions of dollars.

However, despite its global importance, our capacity to monitor and measure Earth’s rapidly changing snow water resources are surprisingly limited. As a result, our understanding of the extent to which we are utilizing this vital resource, as well as details of when, where, or how it is changing or being depleted is severely deficient. The present and urgent challenge at the nexus of water, climate, and human activities in snow-dominated regions is therefore to map SWE and snowmelt to quantify water availability, to identify areas undergoing rapid climate change, and to predict and respond to snow-related hazards. These measurement gaps have been identified multiple times over the last three decades by the National Academies of Science, Engineering and Medicine, but never addressed.

SnowGlobe is a satellite mission proposal submitted to NASA’s 2023 Earth System Explorers Announcement of Opportunity leveraging recent advances in Synthetic Aperture Radar (SAR) technology and satellite systems that make this the right time to tackle this urgent need.  SnowGlobe is a constellation of small satellites using X- and Ku-band SAR to measure global SWE and snow melt onset at the spatial and temporal resolution necessary to capture the evolution of seasonal snow.