Relationships between Snow Water Equivalent, Snow Covered Area, and Topography Using Airborne Snow Observatory Data During the 2013-2016 California Snow-Drought

Study Region. This study was conducted in the Sierra Nevada Mountains of California, USA with a focus on the Tuolumne River Basin. An unprecedented snow-drought occurred within the study area from 2013-2016, dramatically reducing snowpack accumulation.Study Focus. Snow conditions during this drought were explored using a combination of statistical modeling, remotely sensed snow covered area, and Light Detection and Ranging (LIDAR) – based snow water equivalent (SWE) estimates. The primary goal of this research is to explore relationships between snow covered area and SWE and to utilize these relationships toward SWE estimation during the drought period.New Hydrological Insights for the Region. We found that fractional snow covered area (fSCA) significantly improves our ability to model the distribution of SWE based on relationships between SWE, fSCA, and topography. The broad availability of satellite images of fSCA facilitates the transfer of these relationships to different snow-drought years with minimal degradation in performance (r2=0.85, %MAE=33%, %Bias=1%) compared with models fit on the same day, by considering variations in SWE depth as expressed by differences in fSCA between years. This research provides an important means to extend the value of ASO beyond the observations. This insight is important as we expect ASO will continue to provide insights for improving water resource management for years to come.