A Spatial and Temporal Analysis of Radiative Forcing Across a Regional Scale it the Western United States

Snow is a unique land cover type, and varies significantly in reflectance from other types of surfaces on
Earth. Uncontaminated, or ‘clean’, snow has a very high spectral albedo. This is reduced by the deposition of light
absorbing particulates, like dust from arid and disturbed landscapes, which darken the snow surface and enhances
the rate of snow melt. The instantaneous enhanced surface absorption of solar radiation by dust on snow is known as
radiative forcing. Radiative forcing by dust on snow can be monitored at the regional scale with the MODIS Dust
Radiative Forcing in Snow (MODDRFS) product. Here present results from the Western US, namely on the Rocky
Mountains and Sierra Nevada Mountains. We show the effect of dust on snow has high interannual variability, and
dust radiative forcing is consistently higher in the Rockies relative to the Sierra Nevada. Gaining a better
understanding of the spatial and temporal patterns of dust on snow in the Western US will help in formulating
effective management of water resources in a region that is dependent on snow melt to meet water demands.
(KEYWORDS: dust-on-snow, albedo, snowmelt, remote sensing)