Pan American interactions of Amazon precipitation, streamflow, and tree growth extremes

HOWARD, I M; FENG, S; VILLALBA, R; TORBENSON, M C A; BARBOSA, A C; LOPEZ, L; FERNANDES, K; STAHLE, D W; GRANATO-SOUZA, D; SCHÖNGART, J; VILLANUEVA, J

ENVIRONMENTAL RESEARCH LETTERS

IOP PUBLISHING LTD

Año: 2020 vol. 15

1748-9326

Rainfall and river levels in the Amazon are associated with significant precipitation anomalies ofopposite sign in temperate North and South America, which is the dominant mode of precipitationvariability in the Americas that often arises during extremes of the El Niño/Southern Oscillation(ENSO). This co-variability of precipitation extremes across the Americas is imprinted on treegrowth and is detected when new tree-ring chronologies from the eastern equatorial Amazon arecompared with hundreds of moisture-sensitive tree-ring chronologies in mid-latitude North andSouth America from 1759 to 2016. Pan-American co-variability exists even though the seasonalityof precipitation and tree growth only partially overlaps between the Amazon and mid-latitudesbecause ENSO forcing of climate can persist for multiple seasons and can orchestrate a coherentresponse, even where the growing seasons are not fully synchronized. The tree-ring data indicatethat the El Niño influence on inter-hemispheric precipitation and tree growth extremes has beenstrong and stable over the past 258-years, but the La Niña influence has been subject to largemulti-decadal changes. These changes have implications for the dynamics and forecasting ofhydroclimatic variability over the Americas and are supported by analyses of the availableinstrumental data and selected climate model simulations.