Daily extreme precipitation events in different datasets in Southeastern South America

OLMO, MATIAS; BETTOLLI MARIA LAURA

Viena

Conferencia; EGU 2018; 2018

European Geophysical Union

Southeastern South America (SESA) covers central-northeastern Argentina, Uruguay and southern portions ofBrazil and Paraguay (20?40 S, 45?65 W). It is a highly populated region with large urban settlements wheresocio-economic activities are mainly based on rainfed agriculture and cattle rising. SESA has been characterizedby a remarkable increment in the frequency and intensity of heavy precipitation events, particularly during thelate 20th century. The region is particularly vulnerable to extreme events which have high hydrologic and socioeconomicimpacts. However, it is still a challenge to better identify the factors and mechanisms that determine thelocation, intensity and frequency of the precipitation extremes and their large impacts. To carry out climate studiesof spatial and temporal variability of daily precipitation extremes, it is necessary to count on long records of highqualityand high-resolution observational datasets. In some areas of SESA, the density of rain gauges may bevery low and/or their temporal coverage may also be limited. Therefore, the characterization and study of extremeprecipitation events over the region should consider as much available information as possible. Taking into accountthese drawbacks, in this work, we compare and evaluate different daily precipitation datasets in order to establishcriteria to define and characterize extreme precipitation events in time and space over SESA. To this end, differentdaily precipitation datasets are used: daily precipitation from meteorological stations of Argentina, Brazil, Uruguayand Paraguay covering the period 1961-2017; and daily gridded precipitation data from CLARIS-LPB (1961-2000), CPC (1979-2017) and TRMM (2000-2017). Daily extremes are defined and compared among the differentdatasets. Precipitation extremes are identified considering different thresholds defined by the 75th, 90th and 95thpercentiles, and their different spatial coverage. This evaluation is performed in the framework of the CORDEXFlagship Pilot Study initiative in southeastern South America ?Extreme precipitation events in Southeastern SouthAmerica: a proposal for a better understanding and modeling?, whose main goal is to study multi-scale processesand interactions (convection, local, regional and remote processes, including the co-behaviour of processes) thatresult in extreme precipitation events using both dynamical and statistical downscaling approaches to providehigh-resolution information over the region.