Documenting 30 years of glacier fluctuations in the Monte San Lorenzo area (47ºS), South PAtagonian Andes, Argentina

DANIEL FALASCHI; SILVIA DELGADO

Malargue

Encuentro; E-ICES-6: International Center for Earth Science-Sexto Encuentro Internacional; 2010

Monte San Lorenzo (ca. 47ºS) is an isolated massif located east of the NorthernPatagonian Icefield (MPI) in the Chilean-Argentinean border. Previous results yielded a total glaciated area of 107 km2 for the year 2004 which comprehend both Chilean and Argentinean glaciers on Monte San Lorenzo, and a 24% areal reduction over the 1984-2004 period. In this review we focus our attention on teh Argentinean glaciers of Monte San Lorenzo and expand the study area to adjacent glaciated peaks (Cerro W, Penitentes and Hermoso) Furthermore, we widen the period under analysis from 1979 to 2008 using a combination of Landsat MSS, TM, ETM+ and ASTER satellite images. MAjor basins and boundaries of perennial ice masses were delineated using the ASTER derived 30-m resolution GDEM. In order to obtain comparable results, satellite images from different years were georeferenced with an image-to-image process. A band ratio method with an interactive masking threshold was applied to each satellite image to differentiate glacier ice from other surfaces. Since all major glaciers on Monte San Lorenzo and other minor glacier tongues in the area show some debris covered portions, the delineation of glacier limits in theses sectors was corrected manually after visual inspection of each image available.