Late PLiocene dIAtom productivity in the western Bay of Bengal: Response to Indian MOnsoon evolution and teleconnections

印度季风(亚洲季风的一个子系统)是地球上最强大的气象现象之一，影响着超过10亿人的生活。然而，在人为气候变化的影响下，它在不久的将来的行为是不确定的，特别是在季节性降水的强度和分布方面。上新世是地球历史上全球气温和二氧化碳水平上升的最新时期，与对下个世纪的预测相似，可以作为未来气候和季风行为的有用类比。该项目将利用353X期间回收的U1445遗址(孟加拉湾西部)的沉积物。由于该地区在353X之前从未进行过科学钻探，因此高分辨率的U1445岩芯是一个无与伦比的机会，可以通过应用复杂的多代理技术，更好地限制上新世以来冰季风的过去行为及其对地表水生产力的影响。在这里，将产生硅藻、生物硅、总有机碳和基于硅藻的d30Si数据，以高分辨率(约3-3.4Kyr)重建地表水的硅质古生产力和硅含量变化，从而跟踪北半球冰川(约3.5-2.5 Ma)之前、期间和之后硅质生产力对夏季风的变化响应。此外，陆源植物遗迹(淡水硅藻和硅藻)的出现将有助于阐明夏季季风引起的降水排放与水团输送的营养物质在河流中的输入问题。这些记录将与来自相同样本的古水文学和植被覆盖(花粉、木炭、XRF获得的元素)和有孔虫组合数据进行比较，这将使我们能够构建轨道步调的气候变化的整体图景。来自这一关键区域的新材料将使我们能够评估季风对外部日照强迫和内部气候边界条件的相对敏感性，包括全球冰量的范围、南半球营养物质的出口和温室气体浓度。这项拟议的研究是一项合作努力，涉及来自德国、英国和美国的几名353X舰载研究人员。

The Indian Monsoon (iMonsoon, a subsystem of the Asian Monsoon) is one of the most powerful meteorological phenomena on Earth, affecting the lives of over a billion people. However, its behavior in the near future under the influence of anthropogenic climate change is uncertain, particularly in terms of the intensity and distribution of seasonal precipitation. The Pliocene is the most recent period in Earth history with similar elevated global temperatures and CO2 levels to those predicted for the coming century, and may serve as a useful analogue for future climate and monsoon behavior. This project will utilize sediments from Site U1445 (western Bay of Bengal) recovered during 353X. As this region has never been scientifically drilled before 353X, high-resolution core U1445 represents an unparalleled opportunity to better constrained the past behavior of the iMonsoon during the last Pliocene and its effect on surface water productivity through the application of sophisticated multi-proxy techniques. Here diatoms, biogenic silica, total organic carbon and diatom-based d30Si data will be generated to reconstruct siliceous paleoproductivity and Si content changes of surface waters at high resolution (ca. 3-3.4 kyr) allowing us to track the changing response of the siliceous productivity to summer iMonsoon before during and after the Northern Hemisphere Glaciation (ca. 3.5-2.5 Ma). Additionally, the occurrence of land-derived plant remains (freshwater diatoms and phytoliths) will help to elucidate the issue of riverine input of nutrients due to summer iMonsoon-induced precipitation discharge vs water masses-transported nutrients. These records will be compared to proxies for paleohydrology and vegetation cover (pollen, charcoal, XRF-gained elements), and foraminifer assemblage data from the same samples, which will allow a holistic picture of orbitally-paced climatic change to be constructed. New material from this critical region will allow us to assess the relative sensitivity of the monsoon to external insolation forcing and internal climate boundary conditions, including the extent of global ice volume, the export of nutrients from the Southern Hemisphere, and greenhouse gas concentrations. The proposed research is a collaborative effort involving several 353X ship-based researchers from Germany, United Kingdom and USA.