Pleistocene Indian Monsoon Rainfall in the Core Convective Region, Bay of Bengal

在印度-亚洲季风区，人口的用水和农业依赖季风降雨，在许多地区，地下水抽取量已经超过了补给量。对季节性降雨的依赖只会随着时间的推移而增加。 树木年轮记录表明，过去1000年的干旱状况超出了历史上已知的程度。该项目旨在了解控制这些极端干旱时期的过程。降水和干旱的长期变化间接地记录在海底沉积物的化学、物理和生物组成中。通过分析孟加拉湾获得的钻孔岩心沉积物，可以重建过去50万年来的海面温度和季风降雨量的变化。 在本项目期间，这些记录将用于两个目的。 首先，他们将确定季风雨对大气中二氧化碳含量变化的敏感性，全球冰量和太阳辐射强迫，所有这些在这段时间内都是众所周知的。 其次，这些记录将有助于检查季风区全球模型的准确性。该项目的成果将有助于了解与其他地区极端干旱有关的过程。该项目为一名研究生和一名本科生提供培训。更新世夏季风重建已在阿拉伯海、南中国海和中国东部的长江流域产生。 这些地区是动态连接在现代的大规模大气流动起源于南亚热带印度洋，跨越阿拉伯海，印度，孟加拉湾，印度支那，南中国海和中国东部。 在轨道时间尺度上，这些地区的结果是不同的，指向风和季风水汽输送的脱钩，或代理季节性的误解。 这种现状导致了季风对基本驱动机制的敏感性的强烈不同解释，包括日照，海洋/大气能量交换，冰量和温室气体，所有这些因素都影响了我们对突然和千年尺度变化的理解。 季风降雨将在孟加拉湾和印度的北方地区重建，这是地球上对流最活跃的地区之一。将分析来自印度东北部边缘U1446（2015年1月钻探）的过去50万年的样本。将产生多个独立的记录，每一个跨越过去500 ka的采样间隔为1至2 ka，明确解决轨道尺度的变化。 多代理数据集将区分为解释轨道尺度解释的差异而提出的各种假设。

In the Indo-Asian monsoon region the population depends on monsoonal rains for water and agriculture, and in many regions groundwater withdrawal already exceeds recharge rates. The dependence on seasonal rainfall will only increase over time. Tree-ring records indicate drought conditions over the past 1000 years that are beyond magnitudes known historically. This project seeks to understand the processes controlling these periods of extreme drought. Long-term changes in precipitation and drought are indirectly recorded in the chemical, physical, and biological composition of sediments that slowly accumulate offshore on the sea floor. By analyzing sediments from drill cores obtained in the Bay of Bengal, changes in sea surface temperature and monsoonal rainfall over the past 500,000 years can be reconstructed. During this project the records will serve two purposes. First, they will establish the sensitivity of monsoonal rains to changes in the carbon dioxide content of the atmosphere, global ice volume, and solar radiation forcing, all of which are very well known over this time interval. Second, the records will help to check the accuracy of global models of monsoonal regions. The results of the project will aid in understanding the processes associated with extreme drought in other regions. The project provides training for a graduate student as well as undergraduate students.Pleistocene summer monsoon reconstructions have been produced from the Arabian Sea, the South China Sea, and the Yangtze River basin of eastern China. These regions are dynamically linked in the modern by large-scale atmospheric flow originating in the southern subtropical Indian Ocean, spanning the Arabian Sea, India, the Bay of Bengal, Indochina, the South China Sea and eastern China. At orbital time scales, results from these regions are divergent, pointing either to a decoupling of winds and monsoonal moisture transport, or to a misinterpretation of proxy seasonality. This current state has resulted in strongly divergent interpretations of monsoon sensitivity to fundamental driving mechanisms including insolation, ocean/atmosphere energy exchange, ice volume, and greenhouse gasses, all of which factor into our understanding of abrupt and millennial-scale variability as well. Monsoon rainfall will be reconstructed over the northern Bay of Bengal and India, among the most convectively active regions on Earth. Samples spanning the past 500,000 years from the northeast Indian Margin Site U1446 (drilled January, 2015) will be analyzed. Multiple independent records will be generated, each spanning the past 500 ka at sample intervals of 1 to 2 ka, clearly resolving orbital-scale variance. Multi-proxy data sets will differentiate between hypotheses put forward to explain the divergent orbital scale interpretations.