INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Precipitation variability in the Altiplano during the past 700 years: integrating instrumental, tree-ring and historical records
MORALES M.; CHRISTIE D.; VILLALBA R.; ARANEO D.; PRIETO M. R.; ALVAREZ C.; SILVA J.; GIODA A.
Simposio; II International Symposium: Reconstructing Climate Variations in South America and the Antarctic Peninsula over the last 2000 years; 2010
Precipitation variations in the Altiplano have direct human and environmental impacts, often being associated with droughts and floods. Instrumental records of climate in the tropics are short, fragmentary and heterogeneous. In this study we present a multi-century perspective of past precipitation variations in the Altiplano estimated from historical documents and a precipitation reconstruction based on Polylepis tarapacana tree-rings. The atmospheric circulation patterns associated with precipitation variations over the region were also analyzed. Previous dendrochronological studies have demonstrated the high skill of P. tarapacana as a proxy for precipitation. The radial growth of this tree species is strongly influenced by moisture availability, representing an excellent proxy for past precipitation. The tree-ring reconstruction covers the past 700 years, and captures 54% of the instrumental precipitation va- riance. Spectral analysis of the tree-ring reconstruction reveals significant peaks at interannual, decadal and interdecadal scales which are in agreement with the main oscillatory modes recorded in instrumental records, and the Niño3.4 and PDO indices. In agreement with previous studies, analysis of the main ocean-atmospheric circulation patterns associated with reconstruction show the strong influence of the tropical Pacific on determining dry and wet events across the Altiplano. As water runoff was used to power the silver mills of Potosi, the Spaniards consistently recorded the occurrence of wet/ dry years during the 1585-1807 period in Bolivia. This valuable past hidrocli- matic archive show a remarkable similarity with the tree-ring reconstruction. The significant relationship between these records adds confidence on both proxies as reliable sources of precipitation variations across the Bolivian Altiplano and provides a unique opportunity to better understand climate variability in this region during the past centuries.