The effects of Picea schrenkiana forest litter on snow surface albedo

Abstract

In this paper, we analyze the characteristics of the snow albedo of different underlying surfaces based on measurements of shortwave radiation and observations of forest litter on snow surfaces, both in an open, unforested environment and in areas with differing forest canopy openness. The fractional litter coverage was obtained through the binarization of digital photos of forest litter distributed on snow surfaces. The effects of Picea schrenkiana forest litter on snow albedo were then quantitatively analyzed to establish an empirical formula for the calculation of forest snow albedo. According to the results, forest litter is the dominant factor determining forest snow albedo. Differences caused by vegetation in the proportion of visible radiation vis-à-vis near-infrared radiation and snow grain size (r) are of minor importance. Forest snow albedo values exponentially decrease with the increase in fractional litter coverage. During snow accumulation period, snow albedo can be calculated using a combination of the new snow albedo and the number of days after fresh snowfall. In snowmelt period, snow albedo can be calculated using a combination of the number of days after the snowmelt began, the number of days after fresh snowfall and the accumulated wind speed after such fresh snowfall.