Accumulation Area Ratio and Equilibrium Line Altitude on the Southern Patagonia Icefield, 2000 - 2010, retrieved using MODIS satellite images

Abstract: Estimations of accumulation area ratio (AAR) and equilibrium line altitude (ELA) were carried out on the Southern Patagonia Icefield. The icefield lies on the border between Chile and Argentina on the southern tip of South America. It is the largest mid-latitude ice mass in the world but despite this fact little research has been conducted in the area. The main reasons for this are most likely the harsh weather conditions and remoteness of the area. However, since icefield’s act as a source for fresh water and as an indicator of climate change more research is crucial. This study focuses on three objectives: to map the snow cover, to estimate AAR and ELA and to discuss their variations during the period 2000 to 2010. The Moderate Resolution Imaging Spectroradiometer (MODIS) is particularly useful for studying cloudy areas because it’s high temporal resolution increase the chances of acquiring cloud- free images. Satellite images were processed, classified and analyzed. The classification results yielded large interannual variations but also congruity. The pattern of the snow cover suggest substantial wind control on snow accumulation, particularly snow deposition on eastern slopes. No statistically significant trends of AAR and ELA could be detected, although, a vague decrease in AAR and increase in ELA is recognized. Average values of AAR and ELA estimated over the period yields lower AARs and higher ELAs than previously suggested. The average AAR is calculated to be 0.66. Average ELA is estimated to be 970 m.a.s.l. and 1270 m.a.s.l. for the western and eastern sides, respectively.