Extreme rainfall and hydric condition in Southern La Plata Basin and the associated atmospheric circulation.

PÁNTANO, VANESA; RIVERA, JUAN ANTONIO; RIVERA, JUAN ANTONIO; PENALBA, OLGA C; BETTOLLI, MARIA LAURA; PENALBA, OLGA C; BETTOLLI, MARIA LAURA; PÁNTANO, VANESA

CLIMATE RESEARCH

INTER-RESEARCH

Lugar: Oldendorf/Luhe; Año: 2016 vol. 68 p. 215 - 229

0936-577X

The interaction between land surface and atmosphere plays an important role in theclimate system. Soil−atmosphere feedback mechanisms are analyzed through calculating thehydric condition (HC) of the soil from the water balance. Spatial coherence between HC and theStandardized Precipitation Index (SPI) as well as the circulation patterns associated with rainfallshortages and excess was evaluated over southern La Plata Basin, fulfilling one of the objectivesof the CLARIS LPB project. Monthly precipitation, and maximum and minimum temperaturesregistered at 35 stations over the 1961−2008 period were used to calculate the HC and SPI indiceswhile the characteristics of the associated circulation were derived from daily sea level pressurefields from NCEP DOE Reanalysis 2 for a domain covering South America. Our results show thatthe HC responds better to accumulated precipitation anomalies in relatively short time scales. Dryand wet months were selected based on the SPI, according to several thresholds that define thespatial extension of these events. This analysis shows the diversity of dry and wet events, whichunable to synthesize all the cases, evaluated through both Taylor diagrams and the spatialcomparison of selected cases. Nevertheless, spatial coherence between both indices was found forregional extreme events. The analysis of the circulation showed that specific daily surfacecirculation types contribute to wet and dry cases and have a predominant occurrence related tothe climatology in the development of the extreme hydric events in the region. This researchcomplements previous studies carried out with modeled data and shows the complexity in thepropagation of the precipitation anomalies through the soil/land surface.