Collaborative Research: P2C2--Reconstructing Holocene Dynamics of the Indo-Pacific Tropical Rain Belt using Australian Stalagmites and Coupled Climate Models

合作研究：P2C2——利用澳大利亚石笋和耦合气候模型重建印度洋-太平洋热带雨带全新世动态

• 批准号: 1602544
• 负责人: Rhawn Denniston
• 金额: $ 10.41万
• 依托单位: Cornell College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2022-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1602544&HistoricalAwards=false
• 关键词: Collaborative; Research; P2C2; Reconstructing; Holocene

This collaborative project generally aims to develop a high resolution aragonite stalagmite record of Holocene Indo-Australian Summer Monsoon (IASM) variability from cave KNI-51, located at the southern margin of the Indo-Pacific tropical rain belt (TRB), a region bounded by the austral and boreal summer intertropical convergence zones. Regional monsoons represent the dominant component of low latitude hydroclimate and are sensitive to a wide array of sub-orbital forcings including solar irradiance, ENSO, and volcanic and anthropogenic aerosols. Tropical societies and ecosystems rely heavily on monsoon rainfall, and thus understanding the origin and nature of decadal-scale hydroclimate variability is critical to understanding the dynamics at play in such systems.Recent field studies of Indo-Pacific hydroclimate suggests that over the last millennium, the TRB may have contracted during the Little Ice Age (LIA) thereby producing reduced monsoon rainfall along both the northern and southern margins of the TRB. In contrast, paleohydrologic and modeling studies show that the global TRB shifted southward meridionally at this time, creating anti-phasing (dry/wet) of rainfall between the TRB northern and southern margins. The researchers have developed a sub-decadal resolved (~4 year) late Holocene (the last 3,000 years) IASM reconstruction from cave KNI-51 that, when integrated with paleomonsoon records from Southeast Asia and the Maritime Continent, reveal not only TRB contraction during the LIA, but expansion and contraction at multi-decadal to centennial time scales over the entirety of the late Holocene. The specific research goals of the project are to extend the KNI-51 stalagmite record through the middle and early Holocene (9,000-3,000 years ago) to examine the nature of TRB dynamics during conditions distinct from those of the late Holocene, including elevated contrasts between summer insolation in the Northern and Southern Hemispheres, lower eustatic sea level (and increased exposure of Indo-Pacific continental shelf), intervals of reduced Atlantic meridional overturning circulation, and the El Nino-Southern Oscillation (ENSO) regime. To better understand atmospheric circulation associated with TRB dynamics, these proxy data will be integrated with climate dynamical analyses of the 6,000 year time slice simulations conducted within the Coupled Model Intercomparison Project phase 5/Paleoclimate Modeling Intercomparison Project phase 3 (CMIP5/PMIP3) framework and with the newly available Last Millennium Ensemble (LME) simulations conducted by the National Center for Atmospheric Research (NCAR).The project involves the potential for a unique view of TRB variability over the last 9,000 years and provides an important test of the skill of CMIP5-class models to accurately reproduce associated Indo-Pacific atmospheric dynamics. As the TRB is closely tied to tropical methane production, this research will help refine estimates of regional tropical methane fluxes during the Holocene. The research will be conducted with extensive involvement of undergraduate students thereby providing experience in advanced paleoclimate research and data analysis techniques.

该合作项目的总体目标是开发一个高分辨率的文石石笋记录全新世印度-澳大利亚夏季风（IASM）的变化，从洞穴KNI-51，位于南部边缘的印度-太平洋热带雨带（TRB），一个区域的南部和北部夏季热带辐合带。区域季风是低纬度水文气候的主要组成部分，对包括太阳辐照度、厄尔尼诺/南方涛动、火山和人为气溶胶在内的各种次轨道强迫十分敏感。 热带社会和生态系统严重依赖季风降雨，因此了解十年尺度水文气候变化的起源和性质对于了解此类系统中的动态至关重要。最近对印度-太平洋水文气候的实地研究表明，在过去的一千年中，TRB可能在小冰河时期（LIA）收缩从而沿热带陆缘北方和南部边缘沿着产生减少的季风降雨。 与此相反，古水文和模拟研究表明，全球TRB向南转移，在这个时候，创造反相（干/湿）的TRB北方和南部边缘之间的降雨。研究人员从KNI-51洞穴开发了一个亚十年分辨率（约4年）的晚全新世（过去3,000年）IASM重建，当与东南亚和海洋大陆的古季风记录相结合时，不仅揭示了LIA期间TRB收缩，而且在整个晚全新世的数十年至百年时间尺度上扩张和收缩。该项目的具体研究目标是将KNI-51石笋记录延长至全新世中早期（9000 - 3000年前），以检查在不同于晚全新世的条件下TRB动力学的性质，包括北方和南半球夏季日照之间的对比升高，海平面较低（以及印度洋-太平洋大陆架暴露的增加）、大西洋纬向翻转环流减少的间隔以及厄尔尼诺-南方涛动（ENSO）机制。为了更好地了解与TRB动力学相关的大气环流，这些代用数据将与6，在耦合模型相互比较项目第5阶段/古气候建模相互比较项目第3阶段内进行的千年时间片模拟（CMIP 5/PMIP 3）框架，并与新提供的最后千年Enhancement（LME）模拟进行的国家大气研究中心（该项目涉及对过去9,000年TRB变化的独特看法的潜力，并对CMIP 5级模型准确再现相关的印度-太平洋大气动力学的技能进行了重要测试。 由于TRB与热带甲烷生产密切相关，这项研究将有助于改进全新世期间区域热带甲烷通量的估计。这项研究将在本科生的广泛参与下进行，从而提供先进的古气候研究和数据分析技术的经验。