Response of lake surface area in Patagonia to variations in river discharge and austral climate modes

SCORDO, F.; PICCOLO, M.C.; PERILLO, G.M.E.

MONAHOK

Congreso; GLEON 19; 2017

GLEON

There are contradictory results regarding the effects produced by local climate factors, Southern Oscillation Index (SOI) and Antarctic Oscillation (AAO) over the Argentine Patagonian lakes and rivers between 45-50 °S. Musters (deep lake) and Colhué Huapí (shallow lake) are located in the Argentine Patagonian plains region (45° 34´ S). This study aims to analyze the fluctuations in the areas of both lakes related to meteorological variables and river discharge in the period 1998-2015. The relationships of those variations with the SOI and AAO fluctuations are also analyzed. A multiple regression was estimated between annual series of the lake area, as the dependent variable, and series of total annual discharge, precipitation over the lakes and evaporation from the lakes, as independent variables. Finally, wavelets analysis was performed to study the effect of the regional climate events (AAO and SOI) over the discharge which finally affects lake area. The results showed periods in which the area of the lakes changed from a dry to a wet condition. The model showed that discharge is the main driver of lake area variation. Cross-spectra showed high squared coherence (> 0.7) over an annual and interannual (3- 5 years) periods between discharge and both AAO and SOI. Wavelet analysis showed that discharge in this area was highly influenced by AAO over an annual to biannual period, and by SOI over an interannual period