Tree-ring-based hydroclimatic reconstruction for the northwest Argentine Patagonia since AD 1055 and its teleconnection to large-scale atmospheric circulation

HADAD M. A.; GONZÁLEZ-REYES, ÁLVARO; ROIG, F.A.; MATSKOVSKY, VLADIMIR; CHERUBINI, PAOLO

Lund

Conferencia; Tree Rings in Archaeology, Climatology and Ecology; 2021

Moisture availability has a significant influence on the dynamics, stability andfunction of terrestrial ecosystems. In this study, we use wood samples from 260Austrocedrus chilensis trees growing in northwestern Patagonia to reconstruct theStandardized Precipitation Evapotranspiration Index (SPEI) for the last millennium(1055 - 2014). Our reconstruction explains 41.6% of the variance contained in theNovember-December SPEI at a 1-month scale for the period 1930-2013. The SPEIreconstruction provides a long-term record of pluvial and drought events for the periods1055-1300, 1550-1700, and 1900-2014. Although the SPEI reconstruction indicatesthat the frequency of extreme events has increased since 1950, our record indicatesthat current levels have not exceeded previous levels, particularly those recordedaround the Medieval Warm Period and toward the end of the Little Ice Age. Thespatial and temporal relationships associated with the South Annular Mode and the PacificSea Surface Temperature variability as expressed by the Tripole Index indicate thatthe temporal variability observed in the SPEI reconstruction is modulated byhemispheric-scale atmospheric circulation dynamics. These climate forcings are likelyresponsible for the intensity and the rate of occurrence of extreme weather events innorthwestern Patagonia. Furthermore, the SPEI reconstruction shows a spatial andtemporal pattern similar to that observed in previous PDSI-based reconstructions. Thisstudy provides robust evidence of hydroclimatic variations for extratropicalsectors of South America, improving our knowledge of the climate dynamics duringthe last millennium and allowing us to review the recently observed increase in wetand dry events in a long-term historical context.