From Playas to Peaks: Developing Infrastructure and Methods to Constrain Dust Dynamics and Monitor Impacts on Snow Water Resources in the Intermountain West

Abstract:

Dust deposition on snow darkens the naturally bright surface, lowers albedo, and accelerates melt. It is generally understood that modern dust levels are elevated, driven by human disturbance of landscapes, but controls on high interannual variability in dust deposition are complex and still not well understood. To date, dust on snow has been best studied at Senator Beck Basin (SBB), in the San Juan Mountains of southwestern Colorado, adjacent to the dust producing southern Colorado Plateau. In this region red dust blanketing snow covered peaks is visually dramatic, and in some years the impacts are extreme, accelerating snowmelt by up to 5 weeks. However, remote sensing retrievals show that the magnitude of dust radiative forcing is highly variable across the Intermountain West. It is not understood how dust on snow processes and impacts at SBB scale to other areas, especially those with different dust source regions. This is a notable knowledge gap in the Intermountain West, where landscapes transition from arid basins to mountain peaks across relatively short spatial scales, and the seasonal mountain snowpack is a crucial natural resource. Snow cover exerts controls on mountain ecosystems and climate and snowmelt provides the majority of surface water supply and groundwater recharge. To fill this gap, new snow energy balance sites have been established to create a network of dust on snow study sites spanning a latitudinal gradient from the San Juan to the Wasatch Mountains. We will describe this network and how it is being used to improve snowmelt forecasting by monitoring spatial variability in dust deposition, snow albedo impacts, and accelerated melt. Additionally, we describe how observations at the sites are being coupled with remote sensing observations and land surface models to connect complementary efforts to constrain the dynamics of dust emission, transport, and deposition.