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: 1602520
• 负责人: Yemane Asmerom
• 金额: $ 9.87万
• 依托单位: University of New Mexico
• 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 2020-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1602520&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 KNI-51 洞穴全新世印度-澳大利亚夏季季风 (IASM) 变化的高分辨率文石石笋记录，该洞穴位于印度洋-太平洋热带雨带 (TRB) 的南缘，该地区以印度洋-太平洋热带雨带 (TRB) 为界。受南半球和北半球夏季热带辐合带影响。区域季风是低纬度水文气候的主要组成部分，并且对各种亚轨道强迫敏感，包括太阳辐照度、ENSO、火山和人为气溶胶。 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。最近对印度洋-太平洋水文气候的实地研究表明，在过去的千年里， TRB可能在小冰期（LIA）期间收缩，从而导致TRB北部和南部边缘的季风降雨减少。 相比之下，古水文和模型研究表明，全球TRB此时向经向南移动，在TRB南北边缘之间产生了反相位（干/湿）降雨。研究人员从 KNI-51 洞穴开发了亚十年分辨率（约 4 年）全新世晚期（最近 3000 年）IASM 重建模型，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，但在整个全新世晚期，在数十年到百年时间尺度上的扩张和收缩。该项目的具体研究目标是将 KNI-51 石笋记录扩展到全新世中期和早期（9,000-3,000 年前），以研究与全新世晚期不同的条件下 TRB 动力学的性质，包括北半球和南半球的夏季日照、海平面下降（以及印度洋-太平洋大陆架的暴露增加）、大西洋经向翻转环流减少的间隔以及厄尔尼诺-南方涛动 (ENSO) 状况。为了更好地了解与 TRB 动态相关的大气环流，这些代理数据将与在耦合模型比对项目第 5 阶段/古气候模拟比对项目第 3 阶段 (CMIP5/PMIP3) 框架内进行的 6,000 年时间片模拟的气候动态分析相结合，国家大气研究中心 (NCAR) 进行的新近千年系综 (LME) 模拟。该项目涉及过去 9000 年 TRB 变化的独特视角，为 CMIP5 级模型准确再现相关印度-太平洋大气动力学的技能提供了重要测试。 由于 TRB 与热带甲烷生产密切相关，这项研究将有助于完善对全新世期间区域热带甲烷通量的估计。该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。