Classification of rock glaciers in southern Colorado based on ice content using radar interferometry and thermal remote sensing

Abstract

Remote sensing provides a means of assessing potential water resources stored in alpine ground ice; this study focuses on rock glaciers, in particular. A rock glacier is a landform composed of block of loose debris (talus) cemented with ice. There are many ways of classifying rock glaciers; categorizing them based on activity provides context on their movement and ice content. Active rock glaciers are able to flow due to their ice content, while inactive or relict rock glaciers are unable to flow due to lack of sufficient ice. This study uses satellite based radar interferometry to identify and quantify movement of 87 rock glaciers on seven peaks in Southern Colorado. Once the active flowing rock glaciers and inactive nonflowing rock glaciers had been identified, the thermal properties of each group were studied to determine if it was possible to classify rock glaciers based on activity using satellite based thermal imaging. This was accomplished by comparing the amplitude of variation in land surface temperature derived from Landsat 7 and Landsat 8 to daily NOAA weather observations over different periods. Active rock glaciers demonstrated less variation in temperature annually than inactive rock glaciers, likely due to the ice modulating surface temperatures from below. Because rock glacier ice content affects land surface temperature over a period of 1 year, the depth to the ice was estimated using a skin depth calculation to be between 4.8m and 6.9m. Active and inactive rock glaciers appear to have different thermal characteristics that can be identified in satellite based thermal infrared imagery. Identifying the difference between active and inactive rock glaciers could be important in identifying potential water resources in remote alpine ecosystems, and on Mars, as well as provide insight to the climatic history of the region.