Humidity change in the upper-middle Yangtze River watershed during the MIS3 and its relationship to the East Asian Summer Monsoon

The global warming has led to the frequent occurrence of extreme weather events, and the study of paleoclimatic is crucial for understanding current climate changes. The Marine Isotope Stage 3 (MIS3) represents a relatively warm period within the Last glacial period, characterized by unstable climate conditions with multiple abrupt changes, similar to the present. The Asian summer monsoon (ASM) has a significant effect on the global climate, and its variations directly affect extreme climates and precipitation. Studying the changes in monsoon precipitation during MIS3 helps to understand the prediction of modern climate changes. This study, based on the analysis of optically stimulated luminescence (OSL) dating of loess in the central Yangtze River watershed, combined with environmental magnetism results, reconstructs the history of monsoonal precipitation changes in the upper-middle Yangtze River watershed during MIS3. The results indicate that the central region of the Yangtze River watershed experienced abundant precipitation during MIS3c, relatively less humid conditions during MIS3b, and a more humid pattern during MIS3a. The integration of other climatic forcing characteristics during MIS3 indicates that the variation of the East Asian summer monsoon (EASM) caused by the difference in the pressure gradient between land and sea under the regulation of solar radiation variations at low latitudes in the Northern Hemisphere is the main driving force for the dry and wet changes in the Yangtze River watershed, and the Indo-Pacific warm pool effect (IPWP) is the main source of the humidity changes in the watershed.The variations of the EASM and the strength of the IPWP effect are the primary cause of the 'humid-less humid-humid' characteristics in the hydrological changes of the Yangtze River watershed and their adjacent regions during the MIS3 stage. • Variations in local hydrology during MIS3 were reconstructed in Yangtze River watershed by loess sediments. • During the MIS3, three stages of 'humid-less humid-humid' characterize climate in East Asia. • Humidity changes in East Asia were positively related to EASM during the MIS3. • Sea-land thermal contrast and water vapor transportation regulated humidity changes.