第七届青年地学论坛

Although it is often unresolved, seasonality is an important element in considering paleoenvironmental records and simulated results, and it is therefore critical to address this shortcoming in order to develop accurate reconstructions of past climate. In this study, climatic proxies with seasonal implications (magnetic susceptibility and mean grain size) are deconstructed for several high-resolution loess sections from mid-latitude Asia using the Ensemble Empirical Mode Decomposition (EEMD) method to detect their response to millennial-scale oscillations during the last glaciation. In so doing, we are able to estimate the amplitude and relative contribution of the reconstructed climate components. Combined with an analysis of modern processes, magnetic susceptibility (MS) can be interpreted as representing summer and spring precipitation, while mean grain size (Mz) can be interpreted as representing spring and summer dust activity in the Chinese Loess Plateau (CLP) and southern central Asia (SCA), respectively. Our results show that the spring and summer signals are clearly correlated with Heinrich events, but that the spring signal is more prominent than the summer during the Dansgaard-Oeschger (D-O) cycles. These results are consistent with modelled simulations. The Heinrich mode and glacial mode are thought to modulate the response of the seasonal signal to abrupt climate events. The study highlights the need for further high-resolution climate proxies with robust seasonality indicators in order to develop a deeper understanding of the response of mid-latitude Asia to rapid northern high-latitude climatic events.

seasonality, abrupt climate events, late Quaternary, mid-latitude Asia, Ensemble Empirical Mode Decomposition