Glacier inventory in the Desert Andes of San Juan, Argentina (29°20’S)

PITTE, PIERRE; ESPIZUA, LYDIA E.; FERRI HIDALGO, LIDIA

Valdivia, Chile

Conferencia; International glaciological Conferencia. Ice and climate change: a view from the south; 2010

CECS

A glacier inventory was compiled of four small watersheds (100km2) in the Desert Andes of San Juan, Argentina. The inventorywas based on high resolution satellite images of 2005 to 2007,aerial photos of 1959 to 2000, and was complemented with fieldobservations. The information obtained was digitised on orthorectifiedIkonos images of 3rd January and 1st March 2005, whichwere used as base map. The remote sensing and GIS methodsare described. In the area, 6 glaciers, 15 perennial snow patches(larger than 0.1 ha) and 36 rock glaciers were identified and classifiedfollowing the WGMS instructions. The glaciers studied showseveral features expected in the Desert Andes: glaciers are small,behave as “reservoir glaciers”, show little evidence of ice motion,experienced small front fluctuations, and are largely covered bypenitentes. In normal years only patches of firn are found on theglaciers. Also topographic control is very strong: glaciers developon cold slopes, mainly southeasterly exposed. During the 1959-2007 period, the total debris-free glacier area shrank 19%, largelyinfluenced by Canito Glacier which lost about 40% of its surface.In addition, local meteorological stations data were used to calculatethe isotherms. The active rock glaciers are located above4150 m a.s.l. and define the lower limit of the discontinuous permafrost,which is associated with the mean annual isotherm of -1°C.The equilibrium line altitude (ELA) lies at 5000-5250 m a.s.l., andwas estimated from the median altitude of the studied glaciers.