I'm pretty green when it comes to RS and I'm doing this school project that I need help with. The project is to measure albedo changes for the tongue of a glacier and I'm using R programming to do it. So I got my data from earth explorer and went for the surface reflectance product in order to save some steps. However, the values for these cells are higher than expected, around 2000 depending on the band. I say higher because when I use a weighted average formula for calculating albedo, which I found in some papers cited below, the outcome gives me cell values of around 1000, not the 0 to 1 I would expect for and albedo. The paper mentions its using a surface reflectance as well for this formula.
My question is, is this formula wrong? Albedo = 0.493Band2 + 0.203 Band + 0.150 Band5 + 0.154Band
Or does some other processing need to be done to my Earth Explorer Surface Reflectance Product. https://landsat.usgs.gov/landsat-surface-reflectance-high-level-data-products
Also I'm using Landsat 4-7 images.
Pimentel, Rafael, et al. "Comparison between Snow Albedo Obtained from Landsat TM, ETM+ Imagery and the SPOT VEGETATION Albedo Product in a Mediterranean Mountainous Site." Hydrology 3.1 (2016): 10.
Also, this is really similar but uses TOA instead of surface reflectance: http://yceo.yale.edu/how-convert-landsat-dns-albedo