Extreme precipitation events in the Austral Chaco region of Argentina

LOVINO, MIGUEL A.; MÜLLER, GABRIELA V.; PIERRESTEGUI, MARÍA JOSEFINA; ESPINOSA, EDNA; RODRÍGUEZ, LETICIA

International Journal of Climatology

JOHN WILEY & SONS LTD

Año: 2022 vol. 42 p. 5985 - 6006

1097-0088

This study assesses the intensity, spatial distribution and temporal variability ofextreme precipitation events (EPEs) on different time scales relevant to agriculture andwater resources during the 1901-2016 period over Argentina?s Austral Chaco (ACh).EPEs were identified using a nonparametric approach for the Standardized PrecipitationIndex (SPI). The leading modes of SPI?s variability were detected using the SingularSpectrum Analysis. We also compile and control the quality of precipitation observationsin a scarcely monitored region. The limited number of stations conditions the interpolationof the GPCC v2018 database here used, mainly during the early twentieth century.The EPEs characterized by SPI at a 24-month time scale, which favor long-lastingwater excesses or deficits with hydrological impacts, underwent two differentiated longterm periods: a dry one before 1960 and a wet one from 1960 to 2005. Consistently,seasonal wet EPEs were more frequent during the wet period while seasonal droughtswere more frequent and with larger spatial extent during the dry period. Seasonal EPEs,represented by the SPI at 3-month time scale, can impact agriculture during the crops?critical growth period. Since 2006, the long-term wetting trend has been reversed. If thisbehavior continues into the coming decades, more droughts and less wetness might beexpected.The EPEs present a large interannual variability with 6.3-year and 9-year significantcycles that, combined with long-term trends, favored extremely wet/dry EPEs. Most ofthe wet/dry EPEs occurred during El Niño/La Niña events. Although this relationship isnot straightforward, we found a discriminant ENSO signal between October of the yearwhen an ENSO event starts and February of the next year.Finally, severely dry/wet EPEs tend to have large spatial extent in the ACh region.The central-eastern ACh region experiences the most extreme wet and dry conditions,which makes this area more prone to extreme EPEs