Climate and topographic controls on the variability of snow water equivalent and snowmelt in a continental alpine watershed

Abstract:

Seasonal snowpack is an essential component in the Earth’s surface hydrological cycle and energy balance. Recent climate warming has caused decreased peak snow accumulation, altered snowmelt rates, and earlier snow disappearance in many mountain ecosystems. Understanding and characterizing the spatial and temporal distribution of snow, often reported as snow water equivalent (SWE), is of crucial importance for assessing water availability to surrounding environments. In this study, we provide a comprehensive assessment of the long-term interannual variability of SWE distributions and snowmelt in the alpine Green Lakes Valley located in the Colorado Front Range. We leverage physically-based energy and mass balance models, satellite observations of Fractional Snow Covered Area (FSCA), and long-term quality controlled daily meteorological data to estimate SWE distribution. Using a 23-year record of SWE distribution (i.e. 1997-2019), we evaluate the impacts of topographic and climate variables on interannual variability of SWE and snowmelt. Specifically, we use a linear regression model to compare metrics of elevation, aspect, slope, wind exposure, vegetation fractional coverage, and air temperature against metrics of SWE variability, including the temporal coefficient of variation in annual maximum SWE, the standard deviation of annual maximum SWE, the range in maximum SWE, maximum and average snowmelt rate, and snow disappearance date. The historical relationships between SWE distribution and topography have the potential to elucidate potential ecosystem response to future changes in snowpack and associated impacts on eco-hydrologic processes.