Estimating snow albedo patterns in a Mediterranean site from Landsat TM and ETM+ images

摘要

The albedo of snow affects the shortwave radiative flux at the land-atmosphere interface, so that it therefore plays an important role in the snow mass and energy balance. In semiarid areas, their particular climate conditions enhance the spatiotemporal variability of the snow albedo during the snow cover periods, increasing its difficulty in being measured and monitored. Satellite remote sensing is a powerful tool for measuring snow albedo evolution. Ten years of Landsat-5 and Landsat-7 Thematic Mapper images were analysed to determine a trend in the albedo evolution throughout the year in a Mediterranean site, Sierra Nevada Mountain (Southern Spain). A pattern in snow albedo from all the snow pixel in each Landsat scene was obtained. It ranges from 0.8 in new snow to 0.4 in old dirty snow, with a decreasing rate of 0.003 albedo per day. This trend was validated with 5 specific location, where the snow is more persistent while the pixel remains well-illuminated.