Publication Date:
2016-11-10
Description:
Oxygen isotope ratios in tree rings (δ 18 O TR ) from northern Bolivia record local precipitation δ 18 O and correlate strongly with Amazon basin-wide rainfall. While this is encouraging evidence that δ 18 O TR can be used for palaeoclimate reconstructions, it remains unclear whether variation in δ 18 O TR is truly driven by within-basin processes, thus recording Amazon climate directly, or if the isotope signal may already be imprinted on incoming vapour, perhaps reflecting a pan-tropical climate signal. We use atmospheric back-trajectories combined with satellite observations of precipitation, together with water vapour transport analysis to show that δ 18 O TR in Bolivia are indeed controlled by basin-intrinsic processes, with rainout over the basin the most important factor. Furthermore, interannual variation in basin-wide precipitation and atmospheric circulation are both shown to affect δ 18 O TR . These findings suggest δ 18 O TR can be reliably used to reconstruct Amazon precipitation, and have implications for the interpretation of other palaeoproxy records from the Amazon basin.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics
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