Tropical rainfall over the last two millennia: evidence for a low-latitude hydrologic seesaw


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kira.rehfeld [ at ] awi.de

Abstract

The presence of a low- to mid-latitude interhemispheric hydrologic seesaw is apparent over orbital and glacial-interglacial timescales, but its existence over the most recent past remains unclear. Here we investigate, based on climate proxy reconstructions from both hemispheres, the inter-hemispherical phasing of the Intertropical Convergence Zone (ITCZ) and the low- to mid-latitude teleconnections in the Northern Hemisphere over the past 2000 years. A clear feature is a persistent southward shift of the ITCZ during the Little Ice Age until the beginning of the 19th Century. Strong covariation between our new composite ITCZ-stack and North Atlantic Oscillation (NAO) records reveals a tight coupling between these two synoptic weather and climate phenomena over decadal-to-centennial timescales. This relationship becomes most apparent when comparing two precisely dated, high-resolution paleorainfall records from Belize and Scotland, indicating that the low- to mid-latitude teleconnection was also active over annual-decadal timescales. It is likely a combination of external forcing, i.e., solar and volcanic, and internal feedbacks, that drives the synchronous ITCZ and NAO shifts via energy flux perturbations in the tropics.



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ISI/Scopus peer-reviewed
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Published
Eprint ID
44736
DOI https://www.doi.org/10.1038/srep45809

Cite as
Lechleitner, F. A. , Breitenbach, S. F. , Rehfeld, K. , Ridley, H. E. , Asmerom, Y. , Prufer, K. M. , Marwan, N. , Goswami, B. , Kennett, D. J. , Aquino, V. V. , Polyak, V. , Haug, G. H. , Eglinton, T. I. and Baldini, J. U. (2017): Tropical rainfall over the last two millennia: evidence for a low-latitude hydrologic seesaw , Scientific Reports, 7 (1), 45809- . doi: https://www.doi.org/10.1038/srep45809


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