The Amazon basin is a global center of hydroclimatic variability and biodiversity, but there are only eight instrumental rainfall stations with continuous records longer than 80 years in the entire basin, an area nearly the size of the coterminous US. The first long moisture-sensitive tree-ring chronology has been developed in the eastern equatorial Amazon of Brazil based on dendrochronological analysis of Cedrela cross sections cut during sustainable logging operations near the Rio Paru. The Rio Paru chronology dates from 1786 to 2016 and is significantly correlated with instrumental precipitation observations from 1939 to 2016. The strength and spatial scale of the precipitation signal vary during the instrumental period, but the Rio Paru chronology has been used to develop a preliminary reconstruction of February to November rainfall totals from 1786 to 2016. The reconstruction is related to SSTs in the Atlantic and especially the tropical Pacific, similar to the stronger pattern of association computed for the instrumental rainfall data from the eastern Amazon. The tree-ring data estimate extended drought and wet episodes in the mid- to late-nineteenth century, providing a valuable, long-term perspective on the moisture changes expected to emerge over the Amazon in the coming century due to deforestation and anthropogenic climate change.
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Acknowledgements This study has been funded by the U.S. National Science Foundation (Grant Number AGS-1501321) and is based on the collaboration between the Federal University at Lavras, the Brazilian National Institute of Amazonian Research (INPA) at Manaus, the Argentine Institute of Snow Research, Glaciology, and Environmental Sciences (IANIGLA) in Mendoza, and the University of Arkansas, Fayetteville. D. Granato-Souza was funded in Brazil by the Coordination for the Improvement of Higher Education Personnel (CAPES). We gratefully acknowledge the extensive logistical support and wood donations from Norte Energia (Gilberto Veronese, Miguel Lanzuolo de Paula, Daniel Angelo, Elmar Araújo, José Maria, especially, Jailton Rodriguez Bajos), LEME Energia, the Hudson logging company, and Sr. Evandro Dalmaso and Sra. Eliane Dalmaso of the CEMAL logging firm for their generous logistical support and hospitality. GPCC Precipitation data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.esrl.noaa.gov/psd/. COBE SST data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.esrl.noaa.gov/psd/.
Funding This study was funded by U.S. National Science Foundation (Grant number AGS-1501321) to the University of Arkansas, and by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) to the Federal University of Lavras.
- Equatorial Amazon
- Sea surface temperature
- Tree rings