Climate and Surface Mass Balance at Glaciar Perito Moreno, Southern Patagonia

The mass budget of southern Patagonian glaciers is characterized by an extreme amount of surface ablation. To understand the processes controlling surface mass balance, we analyzed in situ data including meteorological variables , ablation stakes for the 25 years between 1996 and 2020 near the terminus of Glaciar Perito Moreno in southern Patagonia in South America. The mean annual temperature has increased over the study period at a rate of 0.28C decade -1. An energy-balance model was applied to calculate a point surface mass balance, based on meteorological records. The average point surface mass balance is estimated to be-16.3 m water equivalent (w.e.) yr -1 between 1996 and 2020, decreasing at a rate in the range from-0.4 to-0.9 m w.e. yr -1 decade -1. The greatest contribution to the surface en-ergy balance was due to the sensible heat flux , its variation drove the surface mass balance variation. The meteo-rological and surface mass balance records were compared with the Southern Annular Mode and El Nin similar to o-Southern Oscillation, which change the atmospheric circulation over southern Patagonia and influence surface mass balance near the terminus of the glacier. Our long-term dataset investigates the detailed meteorological conditions and surface mass balance and their connection with the large-scale climate variability over the last 25 years, reported for the first time in Patagonia.