Tracing the centennial variation of East Asian Summer Monsoon: Insights from three key periods

The centennial-scale variation of the East Asian Summer Monsoon (EASM) circulation has a long-term impact on regional ecosystems, agriculture and water resources. However, the feature and underlying mechanism of the centennial-scale variation in the monsoon system are not well-understood, largely due to the limited meteorological instrumental observation. To address this gap, we selected three characteristic periods (the pre-instrumental, the modern, and the future centennial periods) and compared them using a comparative approach that integrates proxy data analysis and climate model simulation. The results showed that EASM was significantly negatively correlated with temperature in the pre-tool period and the current warm period. On the contrary, under the RCP8.5 scenario, both EASM and future century temperature show an increasing trend. Additionally, we found that the main modes of precipitation in eastern China during the pre-instrumental period are the dipole mode or the monopole mode, while a shift in the dominant mode of precipitation over Eastern China from the dipole mode during the Current Warm Period (20th century) to the monopole mode in the future (21st century) . Our findings enhance the understanding of the centennial variation of the EASM and provide a foundation for projecting its future trend.