A tree-ring reconstruction of the South Asian summer monsoon index over the past millennium
Abstract
The South Asian summer monsoon (SASM) is a major atmospheric synoptic climate system affecting nearly a quarter of the human population. Climate proxy data derived from tree rings, ice cores, speleothems and other sources can all contribute to an understanding of SASM variability prior to instrumental period. Here, we develop an optimal information extraction (OIE) method, which we use to reconstruct the SASM index (SASMI) over the last millennium using 15 tree-ring chronologies. The record generated is significantly correlated (r = 0.7, p < 0.01) with the instrumental SASMI record on annual timescales; this correlation is higher than that obtained in any previous study. The reconstructed SASMI captures 18 of 26 (69%) reordered historical famine events in India over the last millennium; notably, 11 of 16 short events with durations of 1–3 years are accurately depicted in our reconstruction. Moreover, the reconstructed SASMI is positively correlated with variations in total solar irradiance (TSI) on multi-decadal timescales implying that variations in solar activity may influence the SASM. Based on the response of SASM to 34 significant volcanic events using the superposed epoch analysis, the volcanic forcing may drive a weak SASM in the second year of an eruption.
Citation
Shi , F , Li , J & Wilson , R J S 2014 , ' A tree-ring reconstruction of the South Asian summer monsoon index over the past millennium ' , Scientific Reports , vol. 4 , 6739 . https://doi.org/10.1038/srep06739
Publication
Scientific Reports
Status
Peer reviewed
ISSN
2045-2322Type
Journal article
Rights
Copyright authors 2014. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder in order to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
Description
This study was jointly funded by the 973 Program (2010CB950400) and the National Natural Science Foundation of China (41301220; 41030961). Feng Shi was supported by the China Postdoctoral Science Foundation, China Meteorological Administration, with funding specifically targeted for Drought Research (IAM201213) and the West Light Program for Talent Cultivation of the Chinese Academy of Sciences.Collections
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