Reconstruction of winter monsoon strength by elemental ratio of sediments in the East China Sea

Abstract

The East Asian winter monsoon (EAWM) transports cold air from the high northern latitudes to the mid- and low-latitudes. Thus investigations on its variation pattern and mechanism are essential for acquiring further knowledge on the interplay across the high and low latitudes. Proxies such as grain size and foraminiferal δ18O in marine sediments and elemental ratios in the Chinese loess have been used for the reconstruction of EAWM strength. However, more high-resolution reconstructions for EAWM are required for further understanding the mechanism of climate systems and predicting climate change. In this study, we present a high-resolution time-series of the late Holocene EAWM strength reconstructed by element method. Comparisons of element concentrations, elemental ratios and mean grain size (MGS) of environment-sensitive components in a sediment core from the shelf of the East China Sea indicate that K/Ti ratio is an appropriate proxy for the reconstruction of the EAWM strength. K/Ti ratio exhibits similar trends with proxies of sea surface temperature and EAWM strength in different regions influenced by the EAWM. Warm and cold periods such as the Roman Warm Period, Medieval Warm Period and Little Ice Age are identified in the reconstructed results. Total solar irradiance anomaly (ΔTSI) and K/Ti ratios exhibit comparable tendencies in the last two millennia and frequency spectrum analysis exhibits similar periodicities in the time series of ΔTSI and K/Ti, which confirm that solar irradiance has a significant impact on the EASM on centennial time scale.