EXTREME PRECIPITATIONS IN ARGENTINA

MARIANO RE1,2, RAMIRO SAURRAL1 AND VICENTE R. BARROS1,3

Foz de Iguazú

Congreso; 8th International Conference of the Southern Hemisphere Meteorology and Oceanography; 2006

American Meteorological Society

Over the last few decades the South Eastern region of South America has witnessed important increases in mean and extreme precipitations, and consequently severe floods with higher frequency. Important productive zones and numerous urban centers have suffered the effects of this problem. Barros & Bejarán (2005), wonder whether the higher level of precipitations and the changes in extreme events of the last decades will continue in the coming decades or whether, on the contrary and according to an extended view among some professional circles, it is simply a humid cycle;the conclusion they arrive at is that the presentchange is generalized over an enormous surfacearea with an accumulated duration of three decades; therefore, they argue, it would be moreappropriate to speak of climate change rather than of humid cycle. Given this situation and the context of Climate Change, the classic tools to assess risk of flood and design infrastructure, based on the hypothesis of stationary climate series, are not enough. In this work we make an approach tothe new methodologies that allow us to identify and analyze non-stationary series of precipitations. In order to carry out this study, 44 years of data were used (1959-2002 period) in 45 meteorological stations throughout the Central and Eastern Argentine territory (data provided by the National Meteorological Service) Once established the objective of studying extreme precipitations, the daily series were turned into precipitation series of two days with the idea of getting a better picture of extreme rainfall. Observations are made once a day, existing the possibility of occurrence of an extreme event that spreads over the two days surrounding the moment of observation. Therefore, this transformation onsisted in following day (pi+pi+1), choosing as representative, and with the aim of maintaining independence among the data, the maximum of each event. A preliminary analysis allows us to prove that in the period under study there have been changes in the intensity and frequency ofextreme events of precipitation. i+pi+1), choosing as representative, and with the aim of maintaining independence among the data, the maximum of each event. A preliminary analysis allows us to prove that in the period under study there have been changes in the intensity and frequency ofextreme events of precipitation.