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Seasonality of westerly moisture transport in the East Asian Summer Monsoon and its implications for interpreting precipitation δ18O

Baker, A.J.; Sodemann, H.; Baldini, J.U.L.; Breitenbach, S.F.M.; Johnson, K.R.; van Hunen, J.; Pingzhong, Z.

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Authors

A.J. Baker

H. Sodemann

S.F.M. Breitenbach

K.R. Johnson

Z. Pingzhong



Abstract

East Asian summer monsoon (EASM) rainfall impacts the world's most populous regions. Accurate EASM rainfall prediction necessitates robust paleoclimate reconstructions from proxy data and quantitative linkage to modern climatic conditions. Many precisely dated oxygen isotope records from Chinese stalagmites have been interpreted as directly reflecting past EASM rainfall amount variability, but recent research suggests that such records instead integrate multiple hydroclimatic processes. Using a Lagrangian precipitation moisture source diagnostic, we demonstrate that EASM rainfall is primarily derived from the Indian Ocean. Conversely, Pacific Ocean moisture export peaks during winter, and the moisture uptake area does not differ significantly between summer and winter and is thus a minor contributor to monsoonal precipitation. Our results are substantiated by an accurate reproduction of summer and winter spatial rainfall distributions across China. We also correlate modern EASM rainfall oxygen isotope ratios with instrumental rainfall amount and our moisture source data. This analysis reveals that the strength of the source effect is geographically variable, and differences in atmospheric moisture transport may significantly impact the isotopic signature of EASM rainfall at the Hulu, Dongge, and Wanxiang Cave sites. These results improve our ability to isolate the rainfall amount signal in paleomonsoon reconstructions and indicate that precipitation across central and eastern China will directly respond to variability in Indian Ocean moisture supply.

Citation

Baker, A., Sodemann, H., Baldini, J., Breitenbach, S., Johnson, K., van Hunen, J., & Pingzhong, Z. (2015). Seasonality of westerly moisture transport in the East Asian Summer Monsoon and its implications for interpreting precipitation δ18O. Journal of Geophysical Research: Atmospheres, 120(12), 5850-5862. https://doi.org/10.1002/2014jd022919

Journal Article Type Article
Acceptance Date May 20, 2015
Online Publication Date Jun 26, 2015
Publication Date Jun 27, 2015
Deposit Date Jun 26, 2015
Publicly Available Date Apr 20, 2016
Journal Journal of Geophysical Research: Atmospheres
Print ISSN 2169-897X
Electronic ISSN 2169-8996
Publisher American Geophysical Union
Peer Reviewed Peer Reviewed
Volume 120
Issue 12
Pages 5850-5862
DOI https://doi.org/10.1002/2014jd022919

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Copyright Statement
Baker, A. J., H. Sodemann, J. U. L. Baldini, S. F. M. Breitenbach, K. R. Johnson, J.van Hunen, and P. Zhang (2015), Seasonality of westerly moisture transport in the East Asian summer monsoon and its implications for interpreting precipitation δ18O. Journal of Geophysical Research: Atmospheres, 120, 5850-5862, 10.1002/2014JD022919 (DOI). To view the published open abstract, go to http://dx.doi.org and enter the DOI.







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