The mount Tronador glaciar and the Manso River system as sensors of climatic change.

PASQUINI, A.I.; LECOMTE, K.L.; DEPETRIS, P.J.

Mar del Plata, Buenos Aires

Congreso; Las Fronteras de la Física y Química Ambiental en Ibero América” V Congreso Iberoamericano de Física y Química Ambiental.; 2008

Abstract The Manso River system (~41º 20’S, ~71º 40’W) shows a significant negative trend in its historical discharge as well as in lake Mascardi’s water level series. The Manso River upper catchments are mostly fed by meltwater originating in the mount Tronador glacier (3,554 m a.s.l.).  Previous studies in the region have shown that temperatures have increased and atmospheric precipitations have decreased during the last 100 years. The seasonal Kendall test applied on the historical discharge series of the upper and lower Manso River, as well as on Lake Mascardi’s water level series, shows a statistically significant negative trend during the austral spring and summer, when glacial meltwater is the main source for the system. Spectral analyses performed on deseasonalized Manso River discharge and on lake Mascardi’s water level time series show significant (p<0.05) periodic oscillations with interannual (between 2 and 7 years) and decadal periodicity. These signals exhibit a significant squared coherence with the Southern Oscillation Index (SOI), in the equatorial Pacific. Furthermore, other studies have recently shown that Lake Frías –also close to mount Tronador-, shows a clear relationship between the sedimentological record and past ENSO events. We have interpreted the peculiar behavior of Lake Mascardi as a symptom of climatic change, and an indication that melt water is decreasing because the ice volume of the Manso glacier has been markedly diminishing during the last decades.