P2C2: Testing Whether Internal Dynamics is the Pacemaker of the Indian Summer Monsoon Variability on Decadal to Centennial Timescales

P2C2：测试内部动力是否是印度夏季季风十年至百年时间尺度变化的起搏器

• 批准号: 1103360
• 负责人: Ashish Sinha
• 金额: $ 24.28万
• 依托单位: California State University-Dominguez Hills Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1103360&HistoricalAwards=false
• 关键词: P2C2; Testing; Whether; Internal; Dynamics

The researcher aims to develop millennial-length (1,000-2,000), absolute dated, and high resolution (inter-annual to sub-decadal) oxygen isotope records of speleothems from caves located in western, southern, and northern India. The goal of the research is to provide Indian summer monsoon (ISM) histories at the regional level that are analogous to the instrumental records from distinct macro-meteorological units.The investigator notes that seasonal precipitation associated with the ISM tends to be dominated by two time scales of variability: (1) interannual variations which are attributed to slowly evolving external boundary conditions (e.g., tropical Pacific SST), and (2) intraseasonal oscillations (e.g., 10-20 and 30-60 day active-break cycles) which are driven by internal dynamics that modulate convection and propagation of embedded synoptic systems. There is no conclusive evidence to indicate which one of these two forcings is the dominant pacemaker of ISM variability on interannual and longer timescales.The premise of the research is that existing instrumentally-calibrated and inter-annually resolved oxygen isotope speleothem records from central and northeast India supports the hypothesis that the internal forcing, which manifests in the form of chaotic rainfall variability during the monsoon season, is the dominant pacemaker of ISM variability. On the basis of the current data, the research will test the working hypothesis that, on decadal and centennial timescale, systematic changes in the frequency characteristics of active-break cycles serve as a medium by which ISM responds to changes in the external boundary forcing.The broader impacts involve a better understanding of Indian Monsoon dynamics and the support of undergraduates in the research effort from currently under-represented groups.

研究人员的目标是开发位于印度西部，南部和北方洞穴的洞穴沉积物的千年长度（1，000 - 2，000），绝对日期和高分辨率（年际至亚十年）氧同位素记录。 该研究的目的是提供区域水平上的印度夏季风（ISM）历史，类似于不同宏观气象单位的仪器记录。研究者指出，与ISM相关的季节降水往往受两个时间尺度的变化主导：（1）年际变化，归因于缓慢演变的外部边界条件（例如，热带太平洋SST），和（2）季节内振荡（例如，10-20和30-60天的活动中断周期），这些周期由调节嵌入天气系统的对流和传播的内部动力学驱动。没有确凿的证据表明这两种强迫中的哪一种是ISM年际和更长时间尺度变化的主导起搏器。研究的前提是，现有的仪器校准和年际分辨的印度中部和东北部的氧同位素洞穴沉积物记录支持这样的假设，即内部强迫，表现为季风季节混乱的降雨变化形式，是ISM变异性的主要起搏器。 在现有数据的基础上，本研究将测试的工作假设，在十年和百年的时间尺度上，活跃的中断周期的频率特征的系统变化作为一种媒介，ISM响应的变化，在外部边界forcing.The更广泛的影响涉及到更好地了解印度季风动力学和支持本科生的研究工作，从目前代表性不足的群体。