Millenial Scale Weak Monsoon Intervals over India (WeakMonsoons)

印度千禧年规模的弱季风间隔（WeakMonsoons）

• 批准号: 387728878
• 负责人: Professor Dr. Ralph Schneider
• 金额: --
• 依托单位: Institut für Geowissenschaften
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/387728878?language=en
• 关键词: Millenial; Scale; Weak; Monsoon; Intervals

The Indian Summer Monsoon (ISM) is highly variable and sensitive to global climate change. Modern climate observations suggest that mainly Indian Ocean surface temperatures modulate rainfall intensity and seasonal duration over the Indian continent. Based on the manifold paleoclimatic records for past monsoon changes and supported by earth system modelling monsoon variability at orbital and suborbital timescales must be considered as a response to changes in high and low latitude climate change, in atmosphere and ocean circulation, as well as in greenhouse gas concentrations and ice-sheet growth or melt. The importance of theses processes is still extensively, but often controversely, debated. Under the impression of severe flooding events and their devastating impact on millions of people and economic well-being most of these studies have addressed the causes for intervals of enhanced monsoonal precipitation also at geological time scales. However, more recently the focus of paleoclimate reconstructions is oriented towards periods of very low monsoonal precipitation, so-called Weak Monsoon Intervals (WMIs). At millenial timescales WMIs correspond to abrupt cold climate periods characteristic for northern hemishere high latitudes, However, as for the longer timescales, the forcing mechanisms of WMIs are not well understood due to the scarcity of high-resolution Late Quaternary time series of ISM precipitation. This project aims to generate a new record of past multi-centennial variability in rainfall over India using hydrogen and carbon isotope ratios of specific organic compounds from land plants, transported to and deposited in marine sediments in the Bay of Bengal and recently recently drilled at IODP Leg 353, Site U1446. The main objectives are the determination of the magnitude of hydrological responses to external and internal climate forcing during last Glacial and Holocene and to better identify the most importcontrol mechanisms responsible for rainfall variability over India.

印度夏季风（ISM）是一个高度可变的，对全球气候变化非常敏感。现代气候观测表明，主要是印度洋表面温度调节了印度大陆的降雨强度和季节持续时间。根据过去季风变化的多种古气候记录，并得到地球系统建模的支持，必须将轨道和亚轨道时间尺度上的季风变化视为对高纬度和低纬度气候变化、大气和海洋环流以及温室气体浓度和冰盖生长或融化的变化的响应。这些过程的重要性仍然是广泛的，但往往有争议的，辩论。在严重的洪水事件及其对数百万人和经济福祉的破坏性影响的印象下，这些研究中的大多数都在地质时间尺度上解决了季风降水增强的间隔的原因。然而，最近的古气候重建的重点是面向非常低的季风降水，所谓的弱季风间隔（WMIs）的时期。在千年尺度上，WMIs对应于北方高纬度地区的气候突变期，但在更长的时间尺度上，由于缺乏高分辨率的晚第四纪ISM降水序列，WMIs的强迫机制还不清楚。该项目的目的是利用陆地植物中特定有机化合物的氢和碳同位素比率，产生印度过去几百年降雨量变化的新记录，这些有机化合物被运送到孟加拉湾的海洋沉积物中并沉积在海洋沉积物中，最近在IODP第353航段，站点U1446钻探。主要目标是确定水文响应的大小，外部和内部的气候强迫在上个冰期和全新世，以更好地确定最重要的控制机制，负责印度的降雨量变化。