Sediments reveal monsoon precipitation mechanism in central eastern China

Prof. Zhou Xin from University of Science and Technology of China of the Chinese Academy of Sciences and collaborators have reconstructed a high-resolution model of monsoon precipitation in the Jiang-Huai region, and proposed the possible driving mechanism behind it by studying the sediments of Lake Nvshan. The researchers cast their eyes on sediments from Lake Nvshan in Jiang-Huai region, which are less disturbed by human activities. The researchers found that when there is abundant precipitation, which leads to higher lake levels, sediments are apt to possess more reduced conditions and display blue-gray color, and deficient precipitation leads to lower lake levels with sediments more oxidized and thus redder. Through the analysis, researchers realized the 1,800-year multiproxy reconstruction of monsoon precipitation. They detected large fluctuations of sediment redness during the past 1,800 years, during which redness value is higher during Little Ice Age, while during the Medieval Warm Period, indicating a wetter LIA compared to a dryer MWP. However, these results contradicted previous studies, which showed that changes in the Intertropical Convergence Zone should have caused a dryer LIA and a wetter MWP. The researchers believed that this contrast is caused by the fact that the rainfall in the JH region was modulated by the mean state of the tropical Pacific Ocean on centennial time scales. More information: Shiwei Jiang et al, Central eastern China hydrological changes and ENSO-like variability over the past 1800 yr, Geology. Citation: Sediments reveal monsoon precipitation mechanism in central eastern China retrieved 5 August 2021 from https://phys. org/news/2021-08-sediments-reveal-monsoon-precipitation-mechanism.