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Climate of the Past An interactive open-access journal of the European Geosciences Union
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Volume 14, issue 4 | Copyright
Clim. Past, 14, 577-591, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 26 Apr 2018

Research article | 26 Apr 2018

Timescale dependence of the relationship between the East Asian summer monsoon strength and precipitation over eastern China in the last millennium

Jian Shi1, Qing Yan2, and Huijun Wang1,2 Jian Shi et al.
  • 1Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, 210044, China
  • 2Nansen-Zhu International Research Centre, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China

Abstract. Precipitation/humidity proxies are widely used to reconstruct the historical East Asian summer monsoon (EASM) variations based on the assumption that summer precipitation over eastern China is closely and stably linked to the strength of EASM. However, whether the observed EASM–precipitation relationship (e.g., increased precipitation with a stronger EASM) was stable throughout the past remains unclear. In this study, we used model outputs from the Paleoclimate Modelling Intercomparison Project Phase III and Community Earth System Model to investigate the stability of the EASM–precipitation relationship over the last millennium on different timescales. The model results indicate that the EASM strength (defined as the regionally averaged meridional wind) was enhanced in the Medieval Climate Anomaly (MCA;  ∼ 950–1250AD), during which there was increased precipitation over eastern China, and weakened during the Little Ice Age (LIA;  ∼ 1500–1800AD), during which there was decreased precipitation, consistent with precipitation/humidity proxies. However, the simulated EASM–precipitation relationship is only stable on a centennial and longer timescale and is unstable on a shorter timescale. The nonstationary short-timescale EASM–precipitation relationship broadly exhibits a multi-decadal periodicity, which may be attributed to the internal variability of the climate system and has no significant correlation to external forcings. Our results have implications for understanding the discrepancy among various EASM proxies on a multi-decadal timescale and highlight the need to rethink reconstructed decadal EASM variations based on precipitation/humidity proxies.

Publications Copernicus
Short summary
The paleo-East Asian summer monsoon (EASM) is widely reconstructed by precipitation/humidity proxies over East Asia. However, based on numerical simulations over the last millennium, we find that the multi-decadal relationship between the EASM and precipitation over eastern China is non-stationary, which may be attributed to the internal variability of the climate system rather than the external forcings. In contrast, the centennial EASM–precipitation relationship is much more close and stable.
The paleo-East Asian summer monsoon (EASM) is widely reconstructed by precipitation/humidity...