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

HADAD, M A; GONZALEZ-REYES, A.; FIDEL A. ROIG; CHERUBINI, PAOLO

Lund

Congreso; TRACE 2021 Tree Rings in Archaeology, Climatology and Ecology; 2021

Lund University

Moisture availability has a significant influence on the dynamics, stability and function of terrestrial ecosystems. In this study, we use wood samples from 260 Austrocedrus chilensis tres growing in northwestern Patagonia to reconstruct the Standardized Precipitation Evapotrans-piration Index (SPEI) for the last millennium (1055 - 2014). Our reconstruction explains 41.6% of the variance contained in the November-December SPEI at a 1-month scale for the period 1930-2013. The SPEI reconstruction provides a long-term record of pluvial and drought events for the periods 1055-1300, 1550-1700, and 1900-2014. Although the SPEI reconstruction indicates that the frequency of extreme events has increased since1950, our record indicates that current levels have not exceeded previous levels, particularly those recorded around the Medieval Warm Period and toward the end of the Little Ice Age. The spatial and temporal relationships associated with the South Anular Mode and the Pacific Sea Surface Temperature variability as expressed by the Tripole Index indicate that the temporal variability observed in the SPEI reconstruction is modulated by hemispheric-scale atmospheric circulation dynamics. These climate forcings are likely responsible for the intensity and the rate of ocurrence of extreme weather events in northwestern Patagonia. Furthermore, the SPEI reconstruction shows a spatial and temporal pattern similar to that observed in previous PDSI-based reconstructions. This study provides robust evidence of hydroclimatic variations for extratropical sectors of South America, improving our knowledge of the climate dynamics during the last millennium and allowing us to review the recently observed increase in wet and dry events in a long-term historical context.