Multi-scale Snow-Atmosphere Interactions Over Mountain Snowpack for Climate Applications

Abstract:

Key processes regulating alpine snowpack occur on scales ranging from centimeters to meters to kilometers. While it is possible to represent the scales individually with current computational techniques, modeling the finest scale processes over the larger regions useful for many applications remains a challenge. We investigate parameterizations for the representation of snow in large scale models by leveraging a combination of high-resolution lidar derived snow depth maps, topography, and an application of the snow transport resolving SnowModel. Parameterizations are then implemented in the Intermediate Complexity Atmospheric Research model (ICAR) to permit us to test the impact this has on the snow albedo feedback and the representation of climate change. We show that incorporating a better representation of sub-grid scale snowpack variability decreases the snow albedo feedback strength significantly in late spring, and leads to a longer period of weakly enhanced warming stretching into the late summer, when the last seasonal snow finally melts. This variability is controlled by local scale turbulence that we examine with a large-eddy simulation (LES) to better understand additional implications for blowing snow sublimation.