A variety of methods have been used to determine glacier boundaries from optical remote sensing images, including: supervised classification, unsupervised classification, Normalized Difference Snow Index, Band Ratio, visual interpretation, and so on. Among them, visual interpretation has the highest accuracy, especially for discrimination between snow accumulation and debris areas with a low probability of error. Band ratio is also a suitable method in practice.29 Considering the existence of the seasonal snow, shadow areas and small clouds, we did not use these automatic identification methods, which could affect the accuracy. Instead, we primarily relied on visual interpretation and used the TM4/TM5 band ratio as complementary to delineate the glaciers in the Naimona’Nyi region. A threshold was set to 2.3 to separate glaciers from nonglacier covered areas.