A 40+ Year Retrospective of the Airborne Snow Survey Program. Where We Started, Where We Are, and Where We Are Going.

The Office of Water Prediction (OWP) operates the Airborne Gamma Radiation Snow Survey Program to measure snow water equivalent (SWE) and soil moisture using gamma radiation remote sensing. This unique observation system is mounted on low-flying aircraft operated by NOAA’s Office of Marine and Aviation Operations, conducting surveys in 37 states, including Alaska.

The airborne gamma SWE and soil moisture observations are critical to the National Weather Service Weather Forecast Offices and River Forecast Centers in issuing river and flood forecasts, water supply forecasts, and spring flood outlooks. These observations are also incorporated into the OWP National Snow Analysis (NSA) via the SNOW Data Assimilation System (SNODAS). Additionally, various federal, state, and municipal agencies use airborne SWE data in their decision support operations. In many remote areas of the United States, where vulnerable and underserved communities exist, these airborne observations are often the only reliable SWE data available.

This talk will briefly discuss the background, history, and retrospective data dating back to 1980, with a primary focus on the current growth of the program. Key topics include providing actionable intelligence on flooding to isolated and underrepresented communities in Alaska, new flight lines supporting water supply forecasts for the Rio Grande, Pecos, and Upper Colorado basins, and enhancing support for the Rainy and Lake of the Woods River Basins by adding over 35 new flightlines. The discussion will also explore how airborne gamma SWE improves snow and hydrologic models, as well as developments in new hardware, aircraft, products, data visualizations, and the program's future direction.