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

Baker, A. J. ORCID: https://orcid.org/0000-0003-2697-1350, Sodemann, H., Baldini, J. U. L., Breitenbach, S. F. M., Johnson, K. R., van Hunen, J. and Zhang, P. (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). pp. 5850-5862. ISSN 2169-8996 doi: 10.1002/2014JD022919

Abstract/Summary

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.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/58649
Item Type	Article
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > NCAS Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Uncontrolled Keywords	Asian monsoon;moisture sources;oxygen isotopes;rainfall;Lagrangian analysis
Publisher	American Geophysical Union
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