Publication: An Estimation of Past and Present Air Temperature Conditions, Water Equivalent, and Surface Velocity of Rock Glaciers in Cordillera Volcanica, Peru
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2021-01-01
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Abstract
Rock glaciers (RG) are one of the most important geomorphological features in the Peruvian Andes. However, the local characteristics of RG have barely been studied or remain unknown. The aim of this research was to characterize past and present conditions of the RG located in Cordillera Volcanica in the southern of Peru. For this purpose, an inventory of RG was carried out and modern and past regional mean air annual temperatures (MAATs) were calculated. We estimate the water equivalent of RG to assess their importance as possible storage of frozen water for past and present conditions using an empirical rule. In addition, the local surface velocity of RG was obtained from Landsat 8 imagery. Within the study area, 187 RG were identified (surface area of 8.3 km2). Of these, 63 were classified as inactive, 39 as active and 85 as relict forms. The altitudinal distribution of RG ranges between 4616 to 5551 m a.s.l. (meter above sea level) where modern MAAT is 0.9°C. In the current conditions, relict RG are located in positive MAAT levels around 1.4°C, however, for the past conditions, relict RG were located in negative MAAT levels around -5°C. The amount of water stored in intact RG range between 28 and 64 million m3. Meanwhile, for past conditions (paleo-WVE), we estimated that volume stored within rock relict RG was between 16 and 35 million m3 (we assume an ice-rich layer of RG permafrost has between 20-45%). On the other hand, the average surface velocities of the active RG have been estimated between 1 to 10 cm/month. The finding of this research contributes to increasing knowledge about RG in the Peruvian Andes, however, further research is needed to understand the importance of RG as stores of frozen water during the past and present conditions.
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Intact rock glacier | MAAT | Relict rock glacier | surface velocity | water equivalent