SOS

Sublimation of Snow

1 September 2022 - 30 June 2023

Lead Scientist: Jessica Lundquist

Observatory: AMF (ARM Mobile Facility 2) - GUC

Snow is a vital part of water resources, but sublimation may remove 10% to 90% of snowfall from the system. The processes controlling sublimation span multiple scales of measurement and multiple disciplinary fields. Due to a critical lack of reliable direct measurements of snow sublimation, we do not fully understand the physics that govern current rates of sublimation, let alone how those amounts might change with the climate.

We will deploy the National Center for Atmospheric Research (NCAR) Earth Observing Laboratory (EOL)’s Integrated Surface Flux System (ISFS) during winter 2022-2023 in conjunction with the U.S. Department of Energy’s Surface Atmosphere Integrated Field Laboratory (SAIL) in the East River Watershed, Colorado. SAIL will measure vertical and horizontally distributed wind fields from radiosondes, a radar wind profiler, a doppler lidar, and distributed meteorological stations. The ISFS system will provide surface flux observations at multiple levels to better understand how basin-scale wind fields interact with surface turbulence and fluxes.

These measurements, combined with energy and mass balance observations and terrestrial lidar scans of the evolving snowfield, will provide benchmarks of the most reliable approaches to measuring snow sublimation in different conditions and improve understanding of sensible and latent heat fluxes in complex terrain. The work is unique because it embeds a detailed study of snow evolution and complex boundary-layer turbulence (requiring flux measured at multiple heights) within a comprehensive field study of larger-scale flows and mixing (SAIL). Together, these measurements will provide insight into how blowing snow influences latent heat fluxes at heights of 0 to 20 m above the snow surface and how wind fields above a stable boundary layer interact with complex terrain to create intermittent turbulent mixing at the surface. The data set will provide new insight into the evolution of the near-surface boundary layer over snow in complex terrain and which processes are most important to understand total seasonal sublimation.