The hydrological signal of the Perito Moreno Glacier damming of Lake Argentino (southern Andean Patagonia): the connection to climate anomalies

The periodic damning of Lake Argentino by the Perito Moreno Glacier (50 degrees 30'S, 73 degrees 00'W) in Argentina's southern Patagonian Andes has been recorded seventeen times since the beginning of this century. Such events are significant factors controlling discharge anomalies (seasonal component removed) of the Santa Cruz River, the sole outlet of Lake Argentino. Power spectrum analysis of the deseasonalized discharge revealed significant period peaks in the 33- to 36-month range and in the 42- to 58-month range. The first frequency is probably determined by the anomalous position of the subtropical anticyclones in the Pacific (with 2-5 years recurrence intervals), whereas the remaining frequencies are coincidental with the multivariate ENSO index (MEI) frequency spectrum. Significant squared coherency (> 0.78) between the Santa Cruz River discharge anomalies and the MEI suggests that there is a significant teleconnection between ENSO occurrences in the Pacific and the Perito Moreno Glacier dynamics. El Nino events, for example, appear to have fostered the advancement of the glacier's snout and influenced the recorded damming-rupture sequence. (C) 2000 Elsevier Science B.V. All rights reserved.